Auto merge of #81761 - m-ou-se:rollup-xp7v07n, r=m-ou-se

Rollup of 9 pull requests

Successful merges:

 - #74304 (Stabilize the Wake trait)
 - #79805 (Rename Iterator::fold_first to reduce and stabilize it)
 - #81556 (introduce future-compatibility warning for forbidden lint groups)
 - #81645 (Add lint for `panic!(123)` which is not accepted in Rust 2021.)
 - #81710 (OsStr eq_ignore_ascii_case takes arg by value)
 - #81711 (add #[inline] to all the public IpAddr functions)
 - #81725 (Move test to be with the others)
 - #81727 (Revert stabilizing integer::BITS.)
 - #81745 (Stabilize poison API of Once, rename poisoned())

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

72 files changed, 1122 insertions, 355 deletions

diff --git a/compiler/rustc_ast/src/lib.rs b/compiler/rustc_ast/src/lib.rs
index 0f411eda49d..ddf52caed08 100644
--- a/compiler/rustc_ast/src/lib.rs
+++ b/compiler/rustc_ast/src/lib.rs
@@ -14,7 +14,6 @@
 #![feature(const_fn_transmute)]
 #![feature(const_panic)]
 #![feature(crate_visibility_modifier)]
-#![feature(iterator_fold_self)]
 #![feature(label_break_value)]
 #![feature(nll)]
 #![feature(or_patterns)]
diff --git a/compiler/rustc_ast/src/mut_visit.rs b/compiler/rustc_ast/src/mut_visit.rs
index 90d31d4801f..024d9687f31 100644
--- a/compiler/rustc_ast/src/mut_visit.rs
+++ b/compiler/rustc_ast/src/mut_visit.rs
@@ -28,7 +28,7 @@ pub trait ExpectOne<A: Array> {
 
 impl<A: Array> ExpectOne<A> for SmallVec<A> {
     fn expect_one(self, err: &'static str) -> A::Item {
-        assert!(self.len() == 1, err);
+        assert!(self.len() == 1, "{}", err);
         self.into_iter().next().unwrap()
     }
 }
diff --git a/compiler/rustc_data_structures/src/lib.rs b/compiler/rustc_data_structures/src/lib.rs
index 36d261fb737..5880bbd3de4 100644
--- a/compiler/rustc_data_structures/src/lib.rs
+++ b/compiler/rustc_data_structures/src/lib.rs
@@ -13,6 +13,7 @@
 #![feature(unboxed_closures)]
 #![feature(generator_trait)]
 #![feature(fn_traits)]
+#![feature(int_bits_const)]
 #![feature(min_specialization)]
 #![feature(auto_traits)]
 #![feature(nll)]
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index e184e929b07..aa882332099 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -901,7 +901,7 @@ impl HandlerInner {
 
     fn span_bug(&mut self, sp: impl Into<MultiSpan>, msg: &str) -> ! {
         self.emit_diag_at_span(Diagnostic::new(Bug, msg), sp);
-        panic!(ExplicitBug);
+        panic::panic_any(ExplicitBug);
     }
 
     fn emit_diag_at_span(&mut self, mut diag: Diagnostic, sp: impl Into<MultiSpan>) {
@@ -955,7 +955,7 @@ impl HandlerInner {
 
     fn bug(&mut self, msg: &str) -> ! {
         self.emit_diagnostic(&Diagnostic::new(Bug, msg));
-        panic!(ExplicitBug);
+        panic::panic_any(ExplicitBug);
     }
 
     fn delay_as_bug(&mut self, diagnostic: Diagnostic) {
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 1c16dc02667..6487b23a6a6 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -358,7 +358,7 @@ impl GenericArgs<'_> {
             .iter()
             .filter(|arg| !arg.is_synthetic())
             .map(|arg| arg.span())
-            .fold_first(|span1, span2| span1.to(span2))
+            .reduce(|span1, span2| span1.to(span2))
     }
 
     /// Returns span encompassing arguments and their surrounding `<>` or `()`
diff --git a/compiler/rustc_hir/src/lib.rs b/compiler/rustc_hir/src/lib.rs
index efc516a662f..c69a9b063ae 100644
--- a/compiler/rustc_hir/src/lib.rs
+++ b/compiler/rustc_hir/src/lib.rs
@@ -6,7 +6,6 @@
 #![feature(const_fn)] // For the unsizing cast on `&[]`
 #![feature(const_panic)]
 #![feature(in_band_lifetimes)]
-#![feature(iterator_fold_self)]
 #![feature(once_cell)]
 #![feature(or_patterns)]
 #![recursion_limit = "256"]
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index 8bd9dad785c..58a9064b919 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -39,6 +39,7 @@ use rustc_session::SessionLintStore;
 use rustc_span::lev_distance::find_best_match_for_name;
 use rustc_span::{symbol::Symbol, MultiSpan, Span, DUMMY_SP};
 use rustc_target::abi::LayoutOf;
+use tracing::debug;
 
 use std::cell::Cell;
 use std::slice;
@@ -336,6 +337,20 @@ impl LintStore {
         }
     }
 
+    /// True if this symbol represents a lint group name.
+    pub fn is_lint_group(&self, lint_name: Symbol) -> bool {
+        debug!(
+            "is_lint_group(lint_name={:?}, lint_groups={:?})",
+            lint_name,
+            self.lint_groups.keys().collect::<Vec<_>>()
+        );
+        let lint_name_str = &*lint_name.as_str();
+        self.lint_groups.contains_key(&lint_name_str) || {
+            let warnings_name_str = crate::WARNINGS.name_lower();
+            lint_name_str == &*warnings_name_str
+        }
+    }
+
     /// Checks the name of a lint for its existence, and whether it was
     /// renamed or removed. Generates a DiagnosticBuilder containing a
     /// warning for renamed and removed lints. This is over both lint
diff --git a/compiler/rustc_lint/src/levels.rs b/compiler/rustc_lint/src/levels.rs
index 18cd25e5d2a..1fc2bd09167 100644
--- a/compiler/rustc_lint/src/levels.rs
+++ b/compiler/rustc_lint/src/levels.rs
@@ -5,7 +5,7 @@ use rustc_ast::attr;
 use rustc_ast::unwrap_or;
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashMap;
-use rustc_errors::{struct_span_err, Applicability};
+use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
 use rustc_hir as hir;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_hir::{intravisit, HirId};
@@ -17,11 +17,15 @@ use rustc_middle::lint::{
 };
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::TyCtxt;
-use rustc_session::lint::{builtin, Level, Lint, LintId};
+use rustc_session::lint::{
+    builtin::{self, FORBIDDEN_LINT_GROUPS},
+    Level, Lint, LintId,
+};
 use rustc_session::parse::feature_err;
 use rustc_session::Session;
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::{source_map::MultiSpan, Span, DUMMY_SP};
+use tracing::debug;
 
 use std::cmp;
 
@@ -51,6 +55,7 @@ pub struct LintLevelsBuilder<'s> {
     id_to_set: FxHashMap<HirId, u32>,
     cur: u32,
     warn_about_weird_lints: bool,
+    store: &'s LintStore,
 }
 
 pub struct BuilderPush {
@@ -59,13 +64,14 @@ pub struct BuilderPush {
 }
 
 impl<'s> LintLevelsBuilder<'s> {
-    pub fn new(sess: &'s Session, warn_about_weird_lints: bool, store: &LintStore) -> Self {
+    pub fn new(sess: &'s Session, warn_about_weird_lints: bool, store: &'s LintStore) -> Self {
         let mut builder = LintLevelsBuilder {
             sess,
             sets: LintLevelSets::new(),
             cur: 0,
             id_to_set: Default::default(),
             warn_about_weird_lints,
+            store,
         };
         builder.process_command_line(sess, store);
         assert_eq!(builder.sets.list.len(), 1);
@@ -120,36 +126,75 @@ impl<'s> LintLevelsBuilder<'s> {
             if let (Level::Forbid, old_src) =
                 self.sets.get_lint_level(id.lint, self.cur, Some(&specs), &self.sess)
             {
-                let mut diag_builder = struct_span_err!(
-                    self.sess,
-                    src.span(),
-                    E0453,
-                    "{}({}) incompatible with previous forbid",
-                    level.as_str(),
-                    src.name(),
+                // Backwards compatibility check:
+                //
+                // We used to not consider `forbid(lint_group)`
+                // as preventing `allow(lint)` for some lint `lint` in
+                // `lint_group`. For now, issue a future-compatibility
+                // warning for this case.
+                let id_name = id.lint.name_lower();
+                let fcw_warning = match old_src {
+                    LintLevelSource::Default => false,
+                    LintLevelSource::Node(symbol, _, _) => self.store.is_lint_group(symbol),
+                    LintLevelSource::CommandLine(symbol, _) => self.store.is_lint_group(symbol),
+                };
+                debug!(
+                    "fcw_warning={:?}, specs.get(&id) = {:?}, old_src={:?}, id_name={:?}",
+                    fcw_warning, specs, old_src, id_name
                 );
-                diag_builder.span_label(src.span(), "overruled by previous forbid");
-                match old_src {
-                    LintLevelSource::Default => {
-                        diag_builder.note(&format!(
-                            "`forbid` lint level is the default for {}",
-                            id.to_string()
-                        ));
-                    }
-                    LintLevelSource::Node(_, forbid_source_span, reason) => {
-                        diag_builder.span_label(forbid_source_span, "`forbid` level set here");
-                        if let Some(rationale) = reason {
-                            diag_builder.note(&rationale.as_str());
+
+                let decorate_diag_builder = |mut diag_builder: DiagnosticBuilder<'_>| {
+                    diag_builder.span_label(src.span(), "overruled by previous forbid");
+                    match old_src {
+                        LintLevelSource::Default => {
+                            diag_builder.note(&format!(
+                                "`forbid` lint level is the default for {}",
+                                id.to_string()
+                            ));
+                        }
+                        LintLevelSource::Node(_, forbid_source_span, reason) => {
+                            diag_builder.span_label(forbid_source_span, "`forbid` level set here");
+                            if let Some(rationale) = reason {
+                                diag_builder.note(&rationale.as_str());
+                            }
+                        }
+                        LintLevelSource::CommandLine(_, _) => {
+                            diag_builder.note("`forbid` lint level was set on command line");
                         }
                     }
-                    LintLevelSource::CommandLine(_, _) => {
-                        diag_builder.note("`forbid` lint level was set on command line");
-                    }
+                    diag_builder.emit();
+                };
+                if !fcw_warning {
+                    let diag_builder = struct_span_err!(
+                        self.sess,
+                        src.span(),
+                        E0453,
+                        "{}({}) incompatible with previous forbid",
+                        level.as_str(),
+                        src.name(),
+                    );
+                    decorate_diag_builder(diag_builder);
+                } else {
+                    self.struct_lint(
+                        FORBIDDEN_LINT_GROUPS,
+                        Some(src.span().into()),
+                        |diag_builder| {
+                            let diag_builder = diag_builder.build(&format!(
+                                "{}({}) incompatible with previous forbid",
+                                level.as_str(),
+                                src.name(),
+                            ));
+                            decorate_diag_builder(diag_builder);
+                        },
+                    );
                 }
-                diag_builder.emit();
 
-                // Retain the forbid lint level
-                return;
+                // Retain the forbid lint level, unless we are
+                // issuing a FCW. In the FCW case, we want to
+                // respect the new setting.
+                if !fcw_warning {
+                    return;
+                }
             }
         }
         specs.insert(id, (level, src));
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index 6f44436e2a0..638b73c27a8 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -55,8 +55,8 @@ mod late;
 mod levels;
 mod methods;
 mod non_ascii_idents;
+mod non_fmt_panic;
 mod nonstandard_style;
-mod panic_fmt;
 mod passes;
 mod redundant_semicolon;
 mod traits;
@@ -81,8 +81,8 @@ use builtin::*;
 use internal::*;
 use methods::*;
 use non_ascii_idents::*;
+use non_fmt_panic::NonPanicFmt;
 use nonstandard_style::*;
-use panic_fmt::PanicFmt;
 use redundant_semicolon::*;
 use traits::*;
 use types::*;
@@ -169,7 +169,7 @@ macro_rules! late_lint_passes {
                 ClashingExternDeclarations: ClashingExternDeclarations::new(),
                 DropTraitConstraints: DropTraitConstraints,
                 TemporaryCStringAsPtr: TemporaryCStringAsPtr,
-                PanicFmt: PanicFmt,
+                NonPanicFmt: NonPanicFmt,
             ]
         );
     };
diff --git a/compiler/rustc_lint/src/non_fmt_panic.rs b/compiler/rustc_lint/src/non_fmt_panic.rs
new file mode 100644
index 00000000000..e98297b692c
--- /dev/null
+++ b/compiler/rustc_lint/src/non_fmt_panic.rs
@@ -0,0 +1,197 @@
+use crate::{LateContext, LateLintPass, LintContext};
+use rustc_ast as ast;
+use rustc_errors::{pluralize, Applicability};
+use rustc_hir as hir;
+use rustc_middle::ty;
+use rustc_parse_format::{ParseMode, Parser, Piece};
+use rustc_span::{sym, symbol::kw, InnerSpan, Span, Symbol};
+
+declare_lint! {
+    /// The `non_fmt_panic` lint detects `panic!(..)` invocations where the first
+    /// argument is not a formatting string.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,no_run
+    /// panic!("{}");
+    /// panic!(123);
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// In Rust 2018 and earlier, `panic!(x)` directly uses `x` as the message.
+    /// That means that `panic!("{}")` panics with the message `"{}"` instead
+    /// of using it as a formatting string, and `panic!(123)` will panic with
+    /// an `i32` as message.
+    ///
+    /// Rust 2021 always interprets the first argument as format string.
+    NON_FMT_PANIC,
+    Warn,
+    "detect single-argument panic!() invocations in which the argument is not a format string",
+    report_in_external_macro
+}
+
+declare_lint_pass!(NonPanicFmt => [NON_FMT_PANIC]);
+
+impl<'tcx> LateLintPass<'tcx> for NonPanicFmt {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
+        if let hir::ExprKind::Call(f, [arg]) = &expr.kind {
+            if let &ty::FnDef(def_id, _) = cx.typeck_results().expr_ty(f).kind() {
+                if Some(def_id) == cx.tcx.lang_items().begin_panic_fn()
+                    || Some(def_id) == cx.tcx.lang_items().panic_fn()
+                    || Some(def_id) == cx.tcx.lang_items().panic_str()
+                {
+                    if let Some(id) = f.span.ctxt().outer_expn_data().macro_def_id {
+                        if cx.tcx.is_diagnostic_item(sym::std_panic_2015_macro, id)
+                            || cx.tcx.is_diagnostic_item(sym::core_panic_2015_macro, id)
+                        {
+                            check_panic(cx, f, arg);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+fn check_panic<'tcx>(cx: &LateContext<'tcx>, f: &'tcx hir::Expr<'tcx>, arg: &'tcx hir::Expr<'tcx>) {
+    if let hir::ExprKind::Lit(lit) = &arg.kind {
+        if let ast::LitKind::Str(sym, _) = lit.node {
+            // The argument is a string literal.
+            check_panic_str(cx, f, arg, &sym.as_str());
+            return;
+        }
+    }
+
+    // The argument is *not* a string literal.
+
+    let (span, panic) = panic_call(cx, f);
+
+    cx.struct_span_lint(NON_FMT_PANIC, arg.span, |lint| {
+        let mut l = lint.build("panic message is not a string literal");
+        l.note("this is no longer accepted in Rust 2021");
+        if span.contains(arg.span) {
+            l.span_suggestion_verbose(
+                arg.span.shrink_to_lo(),
+                "add a \"{}\" format string to Display the message",
+                "\"{}\", ".into(),
+                Applicability::MaybeIncorrect,
+            );
+            if panic == sym::std_panic_macro {
+                l.span_suggestion_verbose(
+                    span.until(arg.span),
+                    "or use std::panic::panic_any instead",
+                    "std::panic::panic_any(".into(),
+                    Applicability::MachineApplicable,
+                );
+            }
+        }
+        l.emit();
+    });
+}
+
+fn check_panic_str<'tcx>(
+    cx: &LateContext<'tcx>,
+    f: &'tcx hir::Expr<'tcx>,
+    arg: &'tcx hir::Expr<'tcx>,
+    fmt: &str,
+) {
+    if !fmt.contains(&['{', '}'][..]) {
+        // No brace, no problem.
+        return;
+    }
+
+    let fmt_span = arg.span.source_callsite();
+
+    let (snippet, style) = match cx.sess().parse_sess.source_map().span_to_snippet(fmt_span) {
+        Ok(snippet) => {
+            // Count the number of `#`s between the `r` and `"`.
+            let style = snippet.strip_prefix('r').and_then(|s| s.find('"'));
+            (Some(snippet), style)
+        }
+        Err(_) => (None, None),
+    };
+
+    let mut fmt_parser =
+        Parser::new(fmt.as_ref(), style, snippet.clone(), false, ParseMode::Format);
+    let n_arguments = (&mut fmt_parser).filter(|a| matches!(a, Piece::NextArgument(_))).count();
+
+    let (span, _) = panic_call(cx, f);
+
+    if n_arguments > 0 && fmt_parser.errors.is_empty() {
+        let arg_spans: Vec<_> = match &fmt_parser.arg_places[..] {
+            [] => vec![fmt_span],
+            v => v.iter().map(|span| fmt_span.from_inner(*span)).collect(),
+        };
+        cx.struct_span_lint(NON_FMT_PANIC, arg_spans, |lint| {
+            let mut l = lint.build(match n_arguments {
+                1 => "panic message contains an unused formatting placeholder",
+                _ => "panic message contains unused formatting placeholders",
+            });
+            l.note("this message is not used as a format string when given without arguments, but will be in Rust 2021");
+            if span.contains(arg.span) {
+                l.span_suggestion(
+                    arg.span.shrink_to_hi(),
+                    &format!("add the missing argument{}", pluralize!(n_arguments)),
+                    ", ...".into(),
+                    Applicability::HasPlaceholders,
+                );
+                l.span_suggestion(
+                    arg.span.shrink_to_lo(),
+                    "or add a \"{}\" format string to use the message literally",
+                    "\"{}\", ".into(),
+                    Applicability::MachineApplicable,
+                );
+            }
+            l.emit();
+        });
+    } else {
+        let brace_spans: Option<Vec<_>> =
+            snippet.filter(|s| s.starts_with('"') || s.starts_with("r#")).map(|s| {
+                s.char_indices()
+                    .filter(|&(_, c)| c == '{' || c == '}')
+                    .map(|(i, _)| fmt_span.from_inner(InnerSpan { start: i, end: i + 1 }))
+                    .collect()
+            });
+        let msg = match &brace_spans {
+            Some(v) if v.len() == 1 => "panic message contains a brace",
+            _ => "panic message contains braces",
+        };
+        cx.struct_span_lint(NON_FMT_PANIC, brace_spans.unwrap_or(vec![span]), |lint| {
+            let mut l = lint.build(msg);
+            l.note("this message is not used as a format string, but will be in Rust 2021");
+            if span.contains(arg.span) {
+                l.span_suggestion(
+                    arg.span.shrink_to_lo(),
+                    "add a \"{}\" format string to use the message literally",
+                    "\"{}\", ".into(),
+                    Applicability::MachineApplicable,
+                );
+            }
+            l.emit();
+        });
+    }
+}
+
+fn panic_call<'tcx>(cx: &LateContext<'tcx>, f: &'tcx hir::Expr<'tcx>) -> (Span, Symbol) {
+    let mut expn = f.span.ctxt().outer_expn_data();
+
+    let mut panic_macro = kw::Empty;
+
+    // Unwrap more levels of macro expansion, as panic_2015!()
+    // was likely expanded from panic!() and possibly from
+    // [debug_]assert!().
+    for &i in
+        &[sym::std_panic_macro, sym::core_panic_macro, sym::assert_macro, sym::debug_assert_macro]
+    {
+        let parent = expn.call_site.ctxt().outer_expn_data();
+        if parent.macro_def_id.map_or(false, |id| cx.tcx.is_diagnostic_item(i, id)) {
+            expn = parent;
+            panic_macro = i;
+        }
+    }
+
+    (expn.call_site, panic_macro)
+}
diff --git a/compiler/rustc_lint/src/panic_fmt.rs b/compiler/rustc_lint/src/panic_fmt.rs
deleted file mode 100644
index 4a6aca72acb..00000000000
--- a/compiler/rustc_lint/src/panic_fmt.rs
+++ /dev/null
@@ -1,155 +0,0 @@
-use crate::{LateContext, LateLintPass, LintContext};
-use rustc_ast as ast;
-use rustc_errors::{pluralize, Applicability};
-use rustc_hir as hir;
-use rustc_middle::ty;
-use rustc_parse_format::{ParseMode, Parser, Piece};
-use rustc_span::{sym, InnerSpan};
-
-declare_lint! {
-    /// The `panic_fmt` lint detects `panic!("..")` with `{` or `}` in the string literal.
-    ///
-    /// ### Example
-    ///
-    /// ```rust,no_run
-    /// panic!("{}");
-    /// ```
-    ///
-    /// {{produces}}
-    ///
-    /// ### Explanation
-    ///
-    /// In Rust 2018 and earlier, `panic!("{}")` panics with the message `"{}"`,
-    /// as a `panic!()` invocation with a single argument does not use `format_args!()`.
-    /// Rust 2021 interprets this string as format string, which breaks this.
-    PANIC_FMT,
-    Warn,
-    "detect braces in single-argument panic!() invocations",
-    report_in_external_macro
-}
-
-declare_lint_pass!(PanicFmt => [PANIC_FMT]);
-
-impl<'tcx> LateLintPass<'tcx> for PanicFmt {
-    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
-        if let hir::ExprKind::Call(f, [arg]) = &expr.kind {
-            if let &ty::FnDef(def_id, _) = cx.typeck_results().expr_ty(f).kind() {
-                if Some(def_id) == cx.tcx.lang_items().begin_panic_fn()
-                    || Some(def_id) == cx.tcx.lang_items().panic_fn()
-                {
-                    check_panic(cx, f, arg);
-                }
-            }
-        }
-    }
-}
-
-fn check_panic<'tcx>(cx: &LateContext<'tcx>, f: &'tcx hir::Expr<'tcx>, arg: &'tcx hir::Expr<'tcx>) {
-    if let hir::ExprKind::Lit(lit) = &arg.kind {
-        if let ast::LitKind::Str(sym, _) = lit.node {
-            let mut expn = f.span.ctxt().outer_expn_data();
-            if let Some(id) = expn.macro_def_id {
-                if cx.tcx.is_diagnostic_item(sym::std_panic_2015_macro, id)
-                    || cx.tcx.is_diagnostic_item(sym::core_panic_2015_macro, id)
-                {
-                    let fmt = sym.as_str();
-                    if !fmt.contains(&['{', '}'][..]) {
-                        return;
-                    }
-
-                    let fmt_span = arg.span.source_callsite();
-
-                    let (snippet, style) =
-                        match cx.sess().parse_sess.source_map().span_to_snippet(fmt_span) {
-                            Ok(snippet) => {
-                                // Count the number of `#`s between the `r` and `"`.
-                                let style = snippet.strip_prefix('r').and_then(|s| s.find('"'));
-                                (Some(snippet), style)
-                            }
-                            Err(_) => (None, None),
-                        };
-
-                    let mut fmt_parser =
-                        Parser::new(fmt.as_ref(), style, snippet.clone(), false, ParseMode::Format);
-                    let n_arguments =
-                        (&mut fmt_parser).filter(|a| matches!(a, Piece::NextArgument(_))).count();
-
-                    // Unwrap more levels of macro expansion, as panic_2015!()
-                    // was likely expanded from panic!() and possibly from
-                    // [debug_]assert!().
-                    for &assert in &[
-                        sym::std_panic_macro,
-                        sym::core_panic_macro,
-                        sym::assert_macro,
-                        sym::debug_assert_macro,
-                    ] {
-                        let parent = expn.call_site.ctxt().outer_expn_data();
-                        if parent
-                            .macro_def_id
-                            .map_or(false, |id| cx.tcx.is_diagnostic_item(assert, id))
-                        {
-                            expn = parent;
-                        }
-                    }
-
-                    if n_arguments > 0 && fmt_parser.errors.is_empty() {
-                        let arg_spans: Vec<_> = match &fmt_parser.arg_places[..] {
-                            [] => vec![fmt_span],
-                            v => v.iter().map(|span| fmt_span.from_inner(*span)).collect(),
-                        };
-                        cx.struct_span_lint(PANIC_FMT, arg_spans, |lint| {
-                            let mut l = lint.build(match n_arguments {
-                                1 => "panic message contains an unused formatting placeholder",
-                                _ => "panic message contains unused formatting placeholders",
-                            });
-                            l.note("this message is not used as a format string when given without arguments, but will be in a future Rust edition");
-                            if expn.call_site.contains(arg.span) {
-                                l.span_suggestion(
-                                    arg.span.shrink_to_hi(),
-                                    &format!("add the missing argument{}", pluralize!(n_arguments)),
-                                    ", ...".into(),
-                                    Applicability::HasPlaceholders,
-                                );
-                                l.span_suggestion(
-                                    arg.span.shrink_to_lo(),
-                                    "or add a \"{}\" format string to use the message literally",
-                                    "\"{}\", ".into(),
-                                    Applicability::MachineApplicable,
-                                );
-                            }
-                            l.emit();
-                        });
-                    } else {
-                        let brace_spans: Option<Vec<_>> = snippet
-                            .filter(|s| s.starts_with('"') || s.starts_with("r#"))
-                            .map(|s| {
-                                s.char_indices()
-                                    .filter(|&(_, c)| c == '{' || c == '}')
-                                    .map(|(i, _)| {
-                                        fmt_span.from_inner(InnerSpan { start: i, end: i + 1 })
-                                    })
-                                    .collect()
-                            });
-                        let msg = match &brace_spans {
-                            Some(v) if v.len() == 1 => "panic message contains a brace",
-                            _ => "panic message contains braces",
-                        };
-                        cx.struct_span_lint(PANIC_FMT, brace_spans.unwrap_or(vec![expn.call_site]), |lint| {
-                            let mut l = lint.build(msg);
-                            l.note("this message is not used as a format string, but will be in a future Rust edition");
-                            if expn.call_site.contains(arg.span) {
-                                l.span_suggestion(
-                                    arg.span.shrink_to_lo(),
-                                    "add a \"{}\" format string to use the message literally",
-                                    "\"{}\", ".into(),
-                                    Applicability::MachineApplicable,
-                                );
-                            }
-                            l.emit();
-                        });
-                    }
-                }
-            }
-        }
-    }
-}
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 43376003840..da62ad3a6b1 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -5,11 +5,49 @@
 //! compiler code, rather than using their own custom pass. Those
 //! lints are all available in `rustc_lint::builtin`.
 
+// ignore-tidy-filelength
+
 use crate::{declare_lint, declare_lint_pass};
 use rustc_span::edition::Edition;
 use rustc_span::symbol::sym;
 
 declare_lint! {
+    /// The `forbidden_lint_groups` lint detects violations of
+    /// `forbid` applied to a lint group. Due to a bug in the compiler,
+    /// these used to be overlooked entirely. They now generate a warning.
+    ///
+    /// ### Example
+    ///
+    /// ```rust
+    /// #![forbid(warnings)]
+    /// #![deny(bad_style)]
+    ///
+    /// fn main() {}
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Recommended fix
+    ///
+    /// If your crate is using `#![forbid(warnings)]`,
+    /// we recommend that you change to `#![deny(warnings)]`.
+    ///
+    /// ### Explanation
+    ///
+    /// Due to a compiler bug, applying `forbid` to lint groups
+    /// previously had no effect. The bug is now fixed but instead of
+    /// enforcing `forbid` we issue this future-compatibility warning
+    /// to avoid breaking existing crates.
+    pub FORBIDDEN_LINT_GROUPS,
+    Warn,
+    "applying forbid to lint-groups",
+    @future_incompatible = FutureIncompatibleInfo {
+        reference: "issue #81670 <https://github.com/rust-lang/rust/issues/81670>",
+        edition: None,
+    };
+}
+
+declare_lint! {
     /// The `ill_formed_attribute_input` lint detects ill-formed attribute
     /// inputs that were previously accepted and used in practice.
     ///
@@ -2888,6 +2926,7 @@ declare_lint_pass! {
     /// Does nothing as a lint pass, but registers some `Lint`s
     /// that are used by other parts of the compiler.
     HardwiredLints => [
+        FORBIDDEN_LINT_GROUPS,
         ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
         ARITHMETIC_OVERFLOW,
         UNCONDITIONAL_PANIC,
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index 0bdccf7b5f0..ca73481b216 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/compiler/rustc_middle/src/lint.rs
@@ -5,7 +5,10 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_errors::{DiagnosticBuilder, DiagnosticId};
 use rustc_hir::HirId;
-use rustc_session::lint::{builtin, Level, Lint, LintId};
+use rustc_session::lint::{
+    builtin::{self, FORBIDDEN_LINT_GROUPS},
+    Level, Lint, LintId,
+};
 use rustc_session::{DiagnosticMessageId, Session};
 use rustc_span::hygiene::MacroKind;
 use rustc_span::source_map::{DesugaringKind, ExpnKind, MultiSpan};
@@ -89,7 +92,12 @@ impl LintLevelSets {
         // If we're about to issue a warning, check at the last minute for any
         // directives against the warnings "lint". If, for example, there's an
         // `allow(warnings)` in scope then we want to respect that instead.
-        if level == Level::Warn {
+        //
+        // We exempt `FORBIDDEN_LINT_GROUPS` from this because it specifically
+        // triggers in cases (like #80988) where you have `forbid(warnings)`,
+        // and so if we turned that into an error, it'd defeat the purpose of the
+        // future compatibility warning.
+        if level == Level::Warn && LintId::of(lint) != LintId::of(FORBIDDEN_LINT_GROUPS) {
             let (warnings_level, warnings_src) =
                 self.get_lint_id_level(LintId::of(builtin::WARNINGS), idx, aux);
             if let Some(configured_warning_level) = warnings_level {
diff --git a/compiler/rustc_middle/src/util/bug.rs b/compiler/rustc_middle/src/util/bug.rs
index e79adcdb545..791d5060fe5 100644
--- a/compiler/rustc_middle/src/util/bug.rs
+++ b/compiler/rustc_middle/src/util/bug.rs
@@ -3,7 +3,7 @@
 use crate::ty::{tls, TyCtxt};
 use rustc_span::{MultiSpan, Span};
 use std::fmt;
-use std::panic::Location;
+use std::panic::{panic_any, Location};
 
 #[cold]
 #[inline(never)]
@@ -32,7 +32,7 @@ fn opt_span_bug_fmt<S: Into<MultiSpan>>(
         match (tcx, span) {
             (Some(tcx), Some(span)) => tcx.sess.diagnostic().span_bug(span, &msg),
             (Some(tcx), None) => tcx.sess.diagnostic().bug(&msg),
-            (None, _) => panic!(msg),
+            (None, _) => panic_any(msg),
         }
     });
     unreachable!();
diff --git a/compiler/rustc_serialize/src/lib.rs b/compiler/rustc_serialize/src/lib.rs
index ea04e7bb44b..53c3adcc20c 100644
--- a/compiler/rustc_serialize/src/lib.rs
+++ b/compiler/rustc_serialize/src/lib.rs
@@ -17,6 +17,7 @@ Core encoding and decoding interfaces.
 #![feature(min_specialization)]
 #![feature(vec_spare_capacity)]
 #![feature(core_intrinsics)]
+#![feature(int_bits_const)]
 #![feature(maybe_uninit_slice)]
 #![feature(new_uninit)]
 #![cfg_attr(test, feature(test))]
diff --git a/compiler/rustc_serialize/tests/leb128.rs b/compiler/rustc_serialize/tests/leb128.rs
index 3e2aab5125a..a2bcf2c251d 100644
--- a/compiler/rustc_serialize/tests/leb128.rs
+++ b/compiler/rustc_serialize/tests/leb128.rs
@@ -1,3 +1,4 @@
+#![feature(int_bits_const)]
 #![feature(maybe_uninit_slice)]
 #![feature(maybe_uninit_uninit_array)]
 
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index 0a1ecced49a..a49979fb7aa 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -102,6 +102,7 @@
 #![feature(fn_traits)]
 #![feature(fundamental)]
 #![feature(inplace_iteration)]
+#![feature(int_bits_const)]
 #![feature(lang_items)]
 #![feature(layout_for_ptr)]
 #![feature(maybe_uninit_ref)]
diff --git a/library/alloc/src/task.rs b/library/alloc/src/task.rs
index a80550a9653..ab7611ae071 100644
--- a/library/alloc/src/task.rs
+++ b/library/alloc/src/task.rs
@@ -1,4 +1,4 @@
-#![unstable(feature = "wake_trait", issue = "69912")]
+#![stable(feature = "wake_trait", since = "1.51.0")]
 //! Types and Traits for working with asynchronous tasks.
 use core::mem::ManuallyDrop;
 use core::task::{RawWaker, RawWakerVTable, Waker};
@@ -16,18 +16,70 @@ use crate::sync::Arc;
 /// to wake up a task is stored in an [`Arc`]. Some executors (especially
 /// those for embedded systems) cannot use this API, which is why [`RawWaker`]
 /// exists as an alternative for those systems.
-#[unstable(feature = "wake_trait", issue = "69912")]
+///
+/// [arc]: ../../std/sync/struct.Arc.html
+///
+/// # Examples
+///
+/// A basic `block_on` function that takes a future and runs it to completion on
+/// the current thread.
+///
+/// **Note:** This example trades correctness for simplicity. In order to prevent
+/// deadlocks, production-grade implementations will also need to handle
+/// intermediate calls to `thread::unpark` as well as nested invocations.
+///
+/// ```rust
+/// use std::future::Future;
+/// use std::sync::Arc;
+/// use std::task::{Context, Poll, Wake};
+/// use std::thread::{self, Thread};
+///
+/// /// A waker that wakes up the current thread when called.
+/// struct ThreadWaker(Thread);
+///
+/// impl Wake for ThreadWaker {
+///     fn wake(self: Arc<Self>) {
+///         self.0.unpark();
+///     }
+/// }
+///
+/// /// Run a future to completion on the current thread.
+/// fn block_on<T>(fut: impl Future<Output = T>) -> T {
+///     // Pin the future so it can be polled.
+///     let mut fut = Box::pin(fut);
+///
+///     // Create a new context to be passed to the future.
+///     let t = thread::current();
+///     let waker = Arc::new(ThreadWaker(t)).into();
+///     let mut cx = Context::from_waker(&waker);
+///
+///     // Run the future to completion.
+///     loop {
+///         match fut.as_mut().poll(&mut cx) {
+///             Poll::Ready(res) => return res,
+///             Poll::Pending => thread::park(),
+///         }
+///     }
+/// }
+///
+/// block_on(async {
+///     println!("Hi from inside a future!");
+/// });
+/// ```
+#[stable(feature = "wake_trait", since = "1.51.0")]
 pub trait Wake {
     /// Wake this task.
-    #[unstable(feature = "wake_trait", issue = "69912")]
+    #[stable(feature = "wake_trait", since = "1.51.0")]
     fn wake(self: Arc<Self>);
 
     /// Wake this task without consuming the waker.
     ///
     /// If an executor supports a cheaper way to wake without consuming the
     /// waker, it should override this method. By default, it clones the
-    /// [`Arc`] and calls `wake` on the clone.
-    #[unstable(feature = "wake_trait", issue = "69912")]
+    /// [`Arc`] and calls [`wake`] on the clone.
+    ///
+    /// [`wake`]: Wake::wake
+    #[stable(feature = "wake_trait", since = "1.51.0")]
     fn wake_by_ref(self: &Arc<Self>) {
         self.clone().wake();
     }
@@ -35,7 +87,7 @@ pub trait Wake {
 
 #[cfg_attr(bootstrap, allow(rustc::ineffective_unstable_trait_impl))]
 #[cfg_attr(not(bootstrap), allow(ineffective_unstable_trait_impl))]
-#[unstable(feature = "wake_trait", issue = "69912")]
+#[stable(feature = "wake_trait", since = "1.51.0")]
 impl<W: Wake + Send + Sync + 'static> From<Arc<W>> for Waker {
     fn from(waker: Arc<W>) -> Waker {
         // SAFETY: This is safe because raw_waker safely constructs
@@ -46,7 +98,7 @@ impl<W: Wake + Send + Sync + 'static> From<Arc<W>> for Waker {
 
 #[cfg_attr(bootstrap, allow(rustc::ineffective_unstable_trait_impl))]
 #[cfg_attr(not(bootstrap), allow(ineffective_unstable_trait_impl))]
-#[unstable(feature = "wake_trait", issue = "69912")]
+#[stable(feature = "wake_trait", since = "1.51.0")]
 impl<W: Wake + Send + Sync + 'static> From<Arc<W>> for RawWaker {
     fn from(waker: Arc<W>) -> RawWaker {
         raw_waker(waker)
diff --git a/library/alloc/tests/lib.rs b/library/alloc/tests/lib.rs
index 9c7343e8cbf..dd98f806451 100644
--- a/library/alloc/tests/lib.rs
+++ b/library/alloc/tests/lib.rs
@@ -17,6 +17,7 @@
 #![feature(binary_heap_retain)]
 #![feature(inplace_iteration)]
 #![feature(iter_map_while)]
+#![feature(int_bits_const)]
 #![feature(vecdeque_binary_search)]
 #![feature(slice_group_by)]
 #![feature(vec_extend_from_within)]
diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs
index c961e2964a9..6b42d456205 100644
--- a/library/core/src/iter/traits/iterator.rs
+++ b/library/core/src/iter/traits/iterator.rs
@@ -2028,7 +2028,8 @@ pub trait Iterator {
         self.try_fold((), call(f))
     }
 
-    /// An iterator method that applies a function, producing a single, final value.
+    /// Folds every element into an accumulator by applying an operation,
+    /// returning the final result.
     ///
     /// `fold()` takes two arguments: an initial value, and a closure with two
     /// arguments: an 'accumulator', and an element. The closure returns the value that
@@ -2049,6 +2050,9 @@ pub trait Iterator {
     /// may not terminate for infinite iterators, even on traits for which a
     /// result is determinable in finite time.
     ///
+    /// Note: [`reduce()`] can be used to use the first element as the initial
+    /// value, if the accumulator type and item type is the same.
+    ///
     /// # Note to Implementors
     ///
     /// Several of the other (forward) methods have default implementations in
@@ -2104,6 +2108,8 @@ pub trait Iterator {
     /// // they're the same
     /// assert_eq!(result, result2);
     /// ```
+    ///
+    /// [`reduce()`]: Iterator::reduce
     #[doc(alias = "reduce")]
     #[doc(alias = "inject")]
     #[inline]
@@ -2120,10 +2126,15 @@ pub trait Iterator {
         accum
     }
 
-    /// The same as [`fold()`], but uses the first element in the
-    /// iterator as the initial value, folding every subsequent element into it.
-    /// If the iterator is empty, return [`None`]; otherwise, return the result
-    /// of the fold.
+    /// Reduces the elements to a single one, by repeatedly applying a reducing
+    /// operation.
+    ///
+    /// If the iterator is empty, returns [`None`]; otherwise, returns the
+    /// result of the reduction.
+    ///
+    /// For iterators with at least one element, this is the same as [`fold()`]
+    /// with the first element of the iterator as the initial value, folding
+    /// every subsequent element into it.
     ///
     /// [`fold()`]: Iterator::fold
     ///
@@ -2132,13 +2143,11 @@ pub trait Iterator {
     /// Find the maximum value:
     ///
     /// ```
-    /// #![feature(iterator_fold_self)]
-    ///
     /// fn find_max<I>(iter: I) -> Option<I::Item>
     ///     where I: Iterator,
     ///           I::Item: Ord,
     /// {
-    ///     iter.fold_first(|a, b| {
+    ///     iter.reduce(|a, b| {
     ///         if a >= b { a } else { b }
     ///     })
     /// }
@@ -2149,8 +2158,8 @@ pub trait Iterator {
     /// assert_eq!(find_max(b.iter()), None);
     /// ```
     #[inline]
-    #[unstable(feature = "iterator_fold_self", issue = "68125")]
-    fn fold_first<F>(mut self, f: F) -> Option<Self::Item>
+    #[stable(feature = "iterator_fold_self", since = "1.51.0")]
+    fn reduce<F>(mut self, f: F) -> Option<Self::Item>
     where
         Self: Sized,
         F: FnMut(Self::Item, Self::Item) -> Self::Item,
@@ -2647,7 +2656,7 @@ pub trait Iterator {
             move |x, y| cmp::max_by(x, y, &mut compare)
         }
 
-        self.fold_first(fold(compare))
+        self.reduce(fold(compare))
     }
 
     /// Returns the element that gives the minimum value from the
@@ -2707,7 +2716,7 @@ pub trait Iterator {
             move |x, y| cmp::min_by(x, y, &mut compare)
         }
 
-        self.fold_first(fold(compare))
+        self.reduce(fold(compare))
     }
 
     /// Reverses an iterator's direction.
diff --git a/library/core/src/macros/panic.md b/library/core/src/macros/panic.md
index a02e74d5e5a..6e502426df9 100644
--- a/library/core/src/macros/panic.md
+++ b/library/core/src/macros/panic.md
@@ -10,22 +10,23 @@ tests. `panic!` is closely tied with the `unwrap` method of both
 `panic!` when they are set to [`None`] or [`Err`] variants.
 
 This macro is used to inject panic into a Rust thread, causing the thread to
-panic entirely. Each thread's panic can be reaped as the [`Box`]`<`[`Any`]`>` type,
-and the single-argument form of the `panic!` macro will be the value which
-is transmitted.
+panic entirely. This macro panics with a string and uses the [`format!`] syntax
+for building the message.
+
+Each thread's panic can be reaped as the [`Box`]`<`[`Any`]`>` type,
+which contains either a `&str` or `String` for regular `panic!()` invocations.
+To panic with a value of another other type, [`panic_any`] can be used.
 
 [`Result`] enum is often a better solution for recovering from errors than
 using the `panic!` macro. This macro should be used to avoid proceeding using
 incorrect values, such as from external sources. Detailed information about
 error handling is found in the [book].
 
-The multi-argument form of this macro panics with a string and has the
-[`format!`] syntax for building a string.
-
 See also the macro [`compile_error!`], for raising errors during compilation.
 
 [ounwrap]: Option::unwrap
 [runwrap]: Result::unwrap
+[`panic_any`]: ../std/panic/fn.panic_any.html
 [`Box`]: ../std/boxed/struct.Box.html
 [`Any`]: crate::any::Any
 [`format!`]: ../std/macro.format.html
@@ -42,6 +43,6 @@ program with code `101`.
 # #![allow(unreachable_code)]
 panic!();
 panic!("this is a terrible mistake!");
-panic!(4); // panic with the value of 4 to be collected elsewhere
 panic!("this is a {} {message}", "fancy", message = "message");
+std::panic::panic_any(4); // panic with the value of 4 to be collected elsewhere
 ```
diff --git a/library/core/src/num/int_macros.rs b/library/core/src/num/int_macros.rs
index 96affd17cc5..8fdd7c9e5d7 100644
--- a/library/core/src/num/int_macros.rs
+++ b/library/core/src/num/int_macros.rs
@@ -32,9 +32,10 @@ macro_rules! int_impl {
         /// # Examples
         ///
         /// ```
+        /// #![feature(int_bits_const)]
         #[doc = concat!("assert_eq!(", stringify!($SelfT), "::BITS, ", stringify!($BITS), ");")]
         /// ```
-        #[stable(feature = "int_bits_const", since = "1.51.0")]
+        #[unstable(feature = "int_bits_const", issue = "76904")]
         pub const BITS: u32 = $BITS;
 
         /// Converts a string slice in a given base to an integer.
diff --git a/library/core/src/num/uint_macros.rs b/library/core/src/num/uint_macros.rs
index aee424b9b13..9fccf3f72ce 100644
--- a/library/core/src/num/uint_macros.rs
+++ b/library/core/src/num/uint_macros.rs
@@ -32,9 +32,10 @@ macro_rules! uint_impl {
         /// # Examples
         ///
         /// ```
+        /// #![feature(int_bits_const)]
         #[doc = concat!("assert_eq!(", stringify!($SelfT), "::BITS, ", stringify!($BITS), ");")]
         /// ```
-        #[stable(feature = "int_bits_const", since = "1.51.0")]
+        #[unstable(feature = "int_bits_const", issue = "76904")]
         pub const BITS: u32 = $BITS;
 
         /// Converts a string slice in a given base to an integer.
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index 26dbcb8569b..bc0e3e059c9 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -70,6 +70,7 @@
 #![feature(partition_point)]
 #![feature(once_cell)]
 #![feature(unsafe_block_in_unsafe_fn)]
+#![feature(int_bits_const)]
 #![feature(nonzero_leading_trailing_zeros)]
 #![feature(const_option)]
 #![feature(integer_atomics)]
diff --git a/library/panic_unwind/src/lib.rs b/library/panic_unwind/src/lib.rs
index 99a0c67fc11..9ce9c477ec0 100644
--- a/library/panic_unwind/src/lib.rs
+++ b/library/panic_unwind/src/lib.rs
@@ -18,6 +18,7 @@
     issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/"
 )]
 #![feature(core_intrinsics)]
+#![feature(int_bits_const)]
 #![feature(lang_items)]
 #![feature(nll)]
 #![feature(panic_unwind)]
diff --git a/library/std/src/ffi/os_str.rs b/library/std/src/ffi/os_str.rs
index 21060182d60..c9c8f68cd9c 100644
--- a/library/std/src/ffi/os_str.rs
+++ b/library/std/src/ffi/os_str.rs
@@ -826,7 +826,7 @@ impl OsStr {
     /// assert!(!OsString::from("Ferrös").eq_ignore_ascii_case("FERRÖS"));
     /// ```
     #[unstable(feature = "osstring_ascii", issue = "70516")]
-    pub fn eq_ignore_ascii_case<S: ?Sized + AsRef<OsStr>>(&self, other: &S) -> bool {
+    pub fn eq_ignore_ascii_case<S: AsRef<OsStr>>(&self, other: S) -> bool {
         self.inner.eq_ignore_ascii_case(&other.as_ref().inner)
     }
 }
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index b6929f59395..961cff661e3 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -329,7 +329,6 @@
 #![feature(unwind_attributes)]
 #![feature(vec_into_raw_parts)]
 #![feature(vec_spare_capacity)]
-#![feature(wake_trait)]
 // NB: the above list is sorted to minimize merge conflicts.
 #![default_lib_allocator]
 
@@ -508,7 +507,7 @@ pub mod task {
     pub use core::task::*;
 
     #[doc(inline)]
-    #[unstable(feature = "wake_trait", issue = "69912")]
+    #[stable(feature = "wake_trait", since = "1.51.0")]
     pub use alloc::task::*;
 }
 
diff --git a/library/std/src/net/ip.rs b/library/std/src/net/ip.rs
index a8a4127d40a..2aa305d7f83 100644
--- a/library/std/src/net/ip.rs
+++ b/library/std/src/net/ip.rs
@@ -150,6 +150,7 @@ impl IpAddr {
     /// ```
     #[rustc_const_stable(feature = "const_ip", since = "1.50.0")]
     #[stable(feature = "ip_shared", since = "1.12.0")]
+    #[inline]
     pub const fn is_unspecified(&self) -> bool {
         match self {
             IpAddr::V4(ip) => ip.is_unspecified(),
@@ -172,6 +173,7 @@ impl IpAddr {
     /// ```
     #[rustc_const_stable(feature = "const_ip", since = "1.50.0")]
     #[stable(feature = "ip_shared", since = "1.12.0")]
+    #[inline]
     pub const fn is_loopback(&self) -> bool {
         match self {
             IpAddr::V4(ip) => ip.is_loopback(),
@@ -195,6 +197,7 @@ impl IpAddr {
     /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0, 0, 0x1c9, 0, 0, 0xafc8, 0, 0x1)).is_global(), true);
     /// ```
     #[rustc_const_unstable(feature = "const_ip", issue = "76205")]
+    #[inline]
     pub const fn is_global(&self) -> bool {
         match self {
             IpAddr::V4(ip) => ip.is_global(),
@@ -217,6 +220,7 @@ impl IpAddr {
     /// ```
     #[rustc_const_stable(feature = "const_ip", since = "1.50.0")]
     #[stable(feature = "ip_shared", since = "1.12.0")]
+    #[inline]
     pub const fn is_multicast(&self) -> bool {
         match self {
             IpAddr::V4(ip) => ip.is_multicast(),
@@ -243,6 +247,7 @@ impl IpAddr {
     /// );
     /// ```
     #[rustc_const_unstable(feature = "const_ip", issue = "76205")]
+    #[inline]
     pub const fn is_documentation(&self) -> bool {
         match self {
             IpAddr::V4(ip) => ip.is_documentation(),
@@ -265,6 +270,7 @@ impl IpAddr {
     /// ```
     #[rustc_const_stable(feature = "const_ip", since = "1.50.0")]
     #[stable(feature = "ipaddr_checker", since = "1.16.0")]
+    #[inline]
     pub const fn is_ipv4(&self) -> bool {
         matches!(self, IpAddr::V4(_))
     }
@@ -284,6 +290,7 @@ impl IpAddr {
     /// ```
     #[rustc_const_stable(feature = "const_ip", since = "1.50.0")]
     #[stable(feature = "ipaddr_checker", since = "1.16.0")]
+    #[inline]
     pub const fn is_ipv6(&self) -> bool {
         matches!(self, IpAddr::V6(_))
     }
@@ -303,6 +310,7 @@ impl Ipv4Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv4", since = "1.32.0")]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
     pub const fn new(a: u8, b: u8, c: u8, d: u8) -> Ipv4Addr {
         // `s_addr` is stored as BE on all machine and the array is in BE order.
         // So the native endian conversion method is used so that it's never swapped.
@@ -360,6 +368,7 @@ impl Ipv4Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
     pub const fn octets(&self) -> [u8; 4] {
         // This returns the order we want because s_addr is stored in big-endian.
         self.inner.s_addr.to_ne_bytes()
@@ -382,6 +391,7 @@ impl Ipv4Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv4", since = "1.32.0")]
     #[stable(feature = "ip_shared", since = "1.12.0")]
+    #[inline]
     pub const fn is_unspecified(&self) -> bool {
         self.inner.s_addr == 0
     }
@@ -402,6 +412,7 @@ impl Ipv4Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
     #[stable(since = "1.7.0", feature = "ip_17")]
+    #[inline]
     pub const fn is_loopback(&self) -> bool {
         self.octets()[0] == 127
     }
@@ -431,6 +442,7 @@ impl Ipv4Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
     #[stable(since = "1.7.0", feature = "ip_17")]
+    #[inline]
     pub const fn is_private(&self) -> bool {
         match self.octets() {
             [10, ..] => true,
@@ -457,6 +469,7 @@ impl Ipv4Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
     #[stable(since = "1.7.0", feature = "ip_17")]
+    #[inline]
     pub const fn is_link_local(&self) -> bool {
         matches!(self.octets(), [169, 254, ..])
     }
@@ -531,6 +544,7 @@ impl Ipv4Addr {
     /// assert_eq!(Ipv4Addr::new(80, 9, 12, 3).is_global(), true);
     /// ```
     #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
+    #[inline]
     pub const fn is_global(&self) -> bool {
         // check if this address is 192.0.0.9 or 192.0.0.10. These addresses are the only two
         // globally routable addresses in the 192.0.0.0/24 range.
@@ -568,6 +582,7 @@ impl Ipv4Addr {
     /// assert_eq!(Ipv4Addr::new(100, 128, 0, 0).is_shared(), false);
     /// ```
     #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
+    #[inline]
     pub const fn is_shared(&self) -> bool {
         self.octets()[0] == 100 && (self.octets()[1] & 0b1100_0000 == 0b0100_0000)
     }
@@ -600,6 +615,7 @@ impl Ipv4Addr {
     /// assert_eq!(Ipv4Addr::new(191, 255, 255, 255).is_ietf_protocol_assignment(), false);
     /// ```
     #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
+    #[inline]
     pub const fn is_ietf_protocol_assignment(&self) -> bool {
         self.octets()[0] == 192 && self.octets()[1] == 0 && self.octets()[2] == 0
     }
@@ -623,6 +639,7 @@ impl Ipv4Addr {
     /// assert_eq!(Ipv4Addr::new(198, 20, 0, 0).is_benchmarking(), false);
     /// ```
     #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
+    #[inline]
     pub const fn is_benchmarking(&self) -> bool {
         self.octets()[0] == 198 && (self.octets()[1] & 0xfe) == 18
     }
@@ -655,6 +672,7 @@ impl Ipv4Addr {
     /// assert_eq!(Ipv4Addr::new(255, 255, 255, 255).is_reserved(), false);
     /// ```
     #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
+    #[inline]
     pub const fn is_reserved(&self) -> bool {
         self.octets()[0] & 240 == 240 && !self.is_broadcast()
     }
@@ -677,6 +695,7 @@ impl Ipv4Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
     #[stable(since = "1.7.0", feature = "ip_17")]
+    #[inline]
     pub const fn is_multicast(&self) -> bool {
         self.octets()[0] >= 224 && self.octets()[0] <= 239
     }
@@ -697,6 +716,7 @@ impl Ipv4Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
     #[stable(since = "1.7.0", feature = "ip_17")]
+    #[inline]
     pub const fn is_broadcast(&self) -> bool {
         u32::from_be_bytes(self.octets()) == u32::from_be_bytes(Self::BROADCAST.octets())
     }
@@ -723,6 +743,7 @@ impl Ipv4Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
     #[stable(since = "1.7.0", feature = "ip_17")]
+    #[inline]
     pub const fn is_documentation(&self) -> bool {
         match self.octets() {
             [192, 0, 2, _] => true,
@@ -753,6 +774,7 @@ impl Ipv4Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
     pub const fn to_ipv6_compatible(&self) -> Ipv6Addr {
         let [a, b, c, d] = self.octets();
         Ipv6Addr {
@@ -776,6 +798,7 @@ impl Ipv4Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv4", since = "1.50.0")]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
     pub const fn to_ipv6_mapped(&self) -> Ipv6Addr {
         let [a, b, c, d] = self.octets();
         Ipv6Addr {
@@ -817,6 +840,7 @@ impl From<Ipv4Addr> for IpAddr {
     ///     IpAddr::from(addr)
     /// )
     /// ```
+    #[inline]
     fn from(ipv4: Ipv4Addr) -> IpAddr {
         IpAddr::V4(ipv4)
     }
@@ -838,6 +862,7 @@ impl From<Ipv6Addr> for IpAddr {
     ///     IpAddr::from(addr)
     /// );
     /// ```
+    #[inline]
     fn from(ipv6: Ipv6Addr) -> IpAddr {
         IpAddr::V6(ipv6)
     }
@@ -875,6 +900,7 @@ impl fmt::Debug for Ipv4Addr {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Clone for Ipv4Addr {
+    #[inline]
     fn clone(&self) -> Ipv4Addr {
         *self
     }
@@ -882,6 +908,7 @@ impl Clone for Ipv4Addr {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl PartialEq for Ipv4Addr {
+    #[inline]
     fn eq(&self, other: &Ipv4Addr) -> bool {
         self.inner.s_addr == other.inner.s_addr
     }
@@ -889,6 +916,7 @@ impl PartialEq for Ipv4Addr {
 
 #[stable(feature = "ip_cmp", since = "1.16.0")]
 impl PartialEq<Ipv4Addr> for IpAddr {
+    #[inline]
     fn eq(&self, other: &Ipv4Addr) -> bool {
         match self {
             IpAddr::V4(v4) => v4 == other,
@@ -899,6 +927,7 @@ impl PartialEq<Ipv4Addr> for IpAddr {
 
 #[stable(feature = "ip_cmp", since = "1.16.0")]
 impl PartialEq<IpAddr> for Ipv4Addr {
+    #[inline]
     fn eq(&self, other: &IpAddr) -> bool {
         match other {
             IpAddr::V4(v4) => self == v4,
@@ -912,6 +941,7 @@ impl Eq for Ipv4Addr {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl hash::Hash for Ipv4Addr {
+    #[inline]
     fn hash<H: hash::Hasher>(&self, s: &mut H) {
         // NOTE:
         // * hash in big endian order
@@ -923,6 +953,7 @@ impl hash::Hash for Ipv4Addr {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl PartialOrd for Ipv4Addr {
+    #[inline]
     fn partial_cmp(&self, other: &Ipv4Addr) -> Option<Ordering> {
         Some(self.cmp(other))
     }
@@ -930,6 +961,7 @@ impl PartialOrd for Ipv4Addr {
 
 #[stable(feature = "ip_cmp", since = "1.16.0")]
 impl PartialOrd<Ipv4Addr> for IpAddr {
+    #[inline]
     fn partial_cmp(&self, other: &Ipv4Addr) -> Option<Ordering> {
         match self {
             IpAddr::V4(v4) => v4.partial_cmp(other),
@@ -940,6 +972,7 @@ impl PartialOrd<Ipv4Addr> for IpAddr {
 
 #[stable(feature = "ip_cmp", since = "1.16.0")]
 impl PartialOrd<IpAddr> for Ipv4Addr {
+    #[inline]
     fn partial_cmp(&self, other: &IpAddr) -> Option<Ordering> {
         match other {
             IpAddr::V4(v4) => self.partial_cmp(v4),
@@ -950,6 +983,7 @@ impl PartialOrd<IpAddr> for Ipv4Addr {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Ord for Ipv4Addr {
+    #[inline]
     fn cmp(&self, other: &Ipv4Addr) -> Ordering {
         // Compare as native endian
         u32::from_be(self.inner.s_addr).cmp(&u32::from_be(other.inner.s_addr))
@@ -974,6 +1008,7 @@ impl From<Ipv4Addr> for u32 {
     /// let addr = Ipv4Addr::new(0xca, 0xfe, 0xba, 0xbe);
     /// assert_eq!(0xcafebabe, u32::from(addr));
     /// ```
+    #[inline]
     fn from(ip: Ipv4Addr) -> u32 {
         let ip = ip.octets();
         u32::from_be_bytes(ip)
@@ -992,6 +1027,7 @@ impl From<u32> for Ipv4Addr {
     /// let addr = Ipv4Addr::from(0xcafebabe);
     /// assert_eq!(Ipv4Addr::new(0xca, 0xfe, 0xba, 0xbe), addr);
     /// ```
+    #[inline]
     fn from(ip: u32) -> Ipv4Addr {
         Ipv4Addr::from(ip.to_be_bytes())
     }
@@ -1009,6 +1045,7 @@ impl From<[u8; 4]> for Ipv4Addr {
     /// let addr = Ipv4Addr::from([13u8, 12u8, 11u8, 10u8]);
     /// assert_eq!(Ipv4Addr::new(13, 12, 11, 10), addr);
     /// ```
+    #[inline]
     fn from(octets: [u8; 4]) -> Ipv4Addr {
         Ipv4Addr::new(octets[0], octets[1], octets[2], octets[3])
     }
@@ -1026,6 +1063,7 @@ impl From<[u8; 4]> for IpAddr {
     /// let addr = IpAddr::from([13u8, 12u8, 11u8, 10u8]);
     /// assert_eq!(IpAddr::V4(Ipv4Addr::new(13, 12, 11, 10)), addr);
     /// ```
+    #[inline]
     fn from(octets: [u8; 4]) -> IpAddr {
         IpAddr::V4(Ipv4Addr::from(octets))
     }
@@ -1046,6 +1084,7 @@ impl Ipv6Addr {
     #[rustc_allow_const_fn_unstable(const_fn_transmute)]
     #[rustc_const_stable(feature = "const_ipv6", since = "1.32.0")]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
     pub const fn new(a: u16, b: u16, c: u16, d: u16, e: u16, f: u16, g: u16, h: u16) -> Ipv6Addr {
         let addr16 = [
             a.to_be(),
@@ -1107,6 +1146,7 @@ impl Ipv6Addr {
     #[rustc_allow_const_fn_unstable(const_fn_transmute)]
     #[rustc_const_stable(feature = "const_ipv6", since = "1.50.0")]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
     pub const fn segments(&self) -> [u16; 8] {
         // All elements in `s6_addr` must be big endian.
         // SAFETY: `[u8; 16]` is always safe to transmute to `[u16; 8]`.
@@ -1142,6 +1182,7 @@ impl Ipv6Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv6", since = "1.50.0")]
     #[stable(since = "1.7.0", feature = "ip_17")]
+    #[inline]
     pub const fn is_unspecified(&self) -> bool {
         u128::from_be_bytes(self.octets()) == u128::from_be_bytes(Ipv6Addr::UNSPECIFIED.octets())
     }
@@ -1162,6 +1203,7 @@ impl Ipv6Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv6", since = "1.50.0")]
     #[stable(since = "1.7.0", feature = "ip_17")]
+    #[inline]
     pub const fn is_loopback(&self) -> bool {
         u128::from_be_bytes(self.octets()) == u128::from_be_bytes(Ipv6Addr::LOCALHOST.octets())
     }
@@ -1186,6 +1228,7 @@ impl Ipv6Addr {
     /// assert_eq!(Ipv6Addr::new(0, 0, 0x1c9, 0, 0, 0xafc8, 0, 0x1).is_global(), true);
     /// ```
     #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
+    #[inline]
     pub const fn is_global(&self) -> bool {
         match self.multicast_scope() {
             Some(Ipv6MulticastScope::Global) => true,
@@ -1211,6 +1254,7 @@ impl Ipv6Addr {
     /// assert_eq!(Ipv6Addr::new(0xfc02, 0, 0, 0, 0, 0, 0, 0).is_unique_local(), true);
     /// ```
     #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
+    #[inline]
     pub const fn is_unique_local(&self) -> bool {
         (self.segments()[0] & 0xfe00) == 0xfc00
     }
@@ -1265,6 +1309,7 @@ impl Ipv6Addr {
     /// [IETF RFC 4291 section 2.5.6]: https://tools.ietf.org/html/rfc4291#section-2.5.6
     /// [RFC 4291 errata 4406]: https://www.rfc-editor.org/errata/eid4406
     #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
+    #[inline]
     pub const fn is_unicast_link_local_strict(&self) -> bool {
         matches!(self.segments(), [0xfe80, 0, 0, 0, ..])
     }
@@ -1318,6 +1363,7 @@ impl Ipv6Addr {
     /// [IETF RFC 4291 section 2.4]: https://tools.ietf.org/html/rfc4291#section-2.4
     /// [RFC 4291 errata 4406]: https://www.rfc-editor.org/errata/eid4406
     #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
+    #[inline]
     pub const fn is_unicast_link_local(&self) -> bool {
         (self.segments()[0] & 0xffc0) == 0xfe80
     }
@@ -1357,6 +1403,7 @@ impl Ipv6Addr {
     ///
     /// [RFC 3879]: https://tools.ietf.org/html/rfc3879
     #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
+    #[inline]
     pub const fn is_unicast_site_local(&self) -> bool {
         (self.segments()[0] & 0xffc0) == 0xfec0
     }
@@ -1379,6 +1426,7 @@ impl Ipv6Addr {
     /// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_documentation(), true);
     /// ```
     #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
+    #[inline]
     pub const fn is_documentation(&self) -> bool {
         (self.segments()[0] == 0x2001) && (self.segments()[1] == 0xdb8)
     }
@@ -1414,6 +1462,7 @@ impl Ipv6Addr {
     /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_unicast_global(), true);
     /// ```
     #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
+    #[inline]
     pub const fn is_unicast_global(&self) -> bool {
         !self.is_multicast()
             && !self.is_loopback()
@@ -1439,6 +1488,7 @@ impl Ipv6Addr {
     /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).multicast_scope(), None);
     /// ```
     #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
+    #[inline]
     pub const fn multicast_scope(&self) -> Option<Ipv6MulticastScope> {
         if self.is_multicast() {
             match self.segments()[0] & 0x000f {
@@ -1472,6 +1522,7 @@ impl Ipv6Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv6", since = "1.50.0")]
     #[stable(since = "1.7.0", feature = "ip_17")]
+    #[inline]
     pub const fn is_multicast(&self) -> bool {
         (self.segments()[0] & 0xff00) == 0xff00
     }
@@ -1498,6 +1549,7 @@ impl Ipv6Addr {
     /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1).to_ipv4_mapped(), None);
     /// ```
     #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
+    #[inline]
     pub const fn to_ipv4_mapped(&self) -> Option<Ipv4Addr> {
         match self.octets() {
             [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, a, b, c, d] => {
@@ -1527,6 +1579,7 @@ impl Ipv6Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv6", since = "1.50.0")]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[inline]
     pub const fn to_ipv4(&self) -> Option<Ipv4Addr> {
         if let [0, 0, 0, 0, 0, 0 | 0xffff, ab, cd] = self.segments() {
             let [a, b] = ab.to_be_bytes();
@@ -1547,6 +1600,7 @@ impl Ipv6Addr {
     /// ```
     #[rustc_const_stable(feature = "const_ipv6", since = "1.32.0")]
     #[stable(feature = "ipv6_to_octets", since = "1.12.0")]
+    #[inline]
     pub const fn octets(&self) -> [u8; 16] {
         self.inner.s6_addr
     }
@@ -1658,6 +1712,7 @@ impl fmt::Debug for Ipv6Addr {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Clone for Ipv6Addr {
+    #[inline]
     fn clone(&self) -> Ipv6Addr {
         *self
     }
@@ -1665,6 +1720,7 @@ impl Clone for Ipv6Addr {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl PartialEq for Ipv6Addr {
+    #[inline]
     fn eq(&self, other: &Ipv6Addr) -> bool {
         self.inner.s6_addr == other.inner.s6_addr
     }
@@ -1672,6 +1728,7 @@ impl PartialEq for Ipv6Addr {
 
 #[stable(feature = "ip_cmp", since = "1.16.0")]
 impl PartialEq<IpAddr> for Ipv6Addr {
+    #[inline]
     fn eq(&self, other: &IpAddr) -> bool {
         match other {
             IpAddr::V4(_) => false,
@@ -1682,6 +1739,7 @@ impl PartialEq<IpAddr> for Ipv6Addr {
 
 #[stable(feature = "ip_cmp", since = "1.16.0")]
 impl PartialEq<Ipv6Addr> for IpAddr {
+    #[inline]
     fn eq(&self, other: &Ipv6Addr) -> bool {
         match self {
             IpAddr::V4(_) => false,
@@ -1695,6 +1753,7 @@ impl Eq for Ipv6Addr {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl hash::Hash for Ipv6Addr {
+    #[inline]
     fn hash<H: hash::Hasher>(&self, s: &mut H) {
         self.inner.s6_addr.hash(s)
     }
@@ -1702,6 +1761,7 @@ impl hash::Hash for Ipv6Addr {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl PartialOrd for Ipv6Addr {
+    #[inline]
     fn partial_cmp(&self, other: &Ipv6Addr) -> Option<Ordering> {
         Some(self.cmp(other))
     }
@@ -1709,6 +1769,7 @@ impl PartialOrd for Ipv6Addr {
 
 #[stable(feature = "ip_cmp", since = "1.16.0")]
 impl PartialOrd<Ipv6Addr> for IpAddr {
+    #[inline]
     fn partial_cmp(&self, other: &Ipv6Addr) -> Option<Ordering> {
         match self {
             IpAddr::V4(_) => Some(Ordering::Less),
@@ -1719,6 +1780,7 @@ impl PartialOrd<Ipv6Addr> for IpAddr {
 
 #[stable(feature = "ip_cmp", since = "1.16.0")]
 impl PartialOrd<IpAddr> for Ipv6Addr {
+    #[inline]
     fn partial_cmp(&self, other: &IpAddr) -> Option<Ordering> {
         match other {
             IpAddr::V4(_) => Some(Ordering::Greater),
@@ -1729,6 +1791,7 @@ impl PartialOrd<IpAddr> for Ipv6Addr {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Ord for Ipv6Addr {
+    #[inline]
     fn cmp(&self, other: &Ipv6Addr) -> Ordering {
         self.segments().cmp(&other.segments())
     }
@@ -1760,6 +1823,7 @@ impl From<Ipv6Addr> for u128 {
     /// );
     /// assert_eq!(0x102030405060708090A0B0C0D0E0F00D_u128, u128::from(addr));
     /// ```
+    #[inline]
     fn from(ip: Ipv6Addr) -> u128 {
         let ip = ip.octets();
         u128::from_be_bytes(ip)
@@ -1782,6 +1846,7 @@ impl From<u128> for Ipv6Addr {
     ///     ),
     ///     addr);
     /// ```
+    #[inline]
     fn from(ip: u128) -> Ipv6Addr {
         Ipv6Addr::from(ip.to_be_bytes())
     }
@@ -1810,6 +1875,7 @@ impl From<[u8; 16]> for Ipv6Addr {
     ///     addr
     /// );
     /// ```
+    #[inline]
     fn from(octets: [u8; 16]) -> Ipv6Addr {
         let inner = c::in6_addr { s6_addr: octets };
         Ipv6Addr::from_inner(inner)
@@ -1839,6 +1905,7 @@ impl From<[u16; 8]> for Ipv6Addr {
     ///     addr
     /// );
     /// ```
+    #[inline]
     fn from(segments: [u16; 8]) -> Ipv6Addr {
         let [a, b, c, d, e, f, g, h] = segments;
         Ipv6Addr::new(a, b, c, d, e, f, g, h)
@@ -1868,6 +1935,7 @@ impl From<[u8; 16]> for IpAddr {
     ///     addr
     /// );
     /// ```
+    #[inline]
     fn from(octets: [u8; 16]) -> IpAddr {
         IpAddr::V6(Ipv6Addr::from(octets))
     }
@@ -1896,6 +1964,7 @@ impl From<[u16; 8]> for IpAddr {
     ///     addr
     /// );
     /// ```
+    #[inline]
     fn from(segments: [u16; 8]) -> IpAddr {
         IpAddr::V6(Ipv6Addr::from(segments))
     }
diff --git a/library/std/src/sync/once.rs b/library/std/src/sync/once.rs
index 6a330834489..2e5f843fc43 100644
--- a/library/std/src/sync/once.rs
+++ b/library/std/src/sync/once.rs
@@ -125,7 +125,7 @@ unsafe impl Send for Once {}
 
 /// State yielded to [`Once::call_once_force()`]’s closure parameter. The state
 /// can be used to query the poison status of the [`Once`].
-#[unstable(feature = "once_poison", issue = "33577")]
+#[stable(feature = "once_poison", since = "1.51.0")]
 #[derive(Debug)]
 pub struct OnceState {
     poisoned: bool,
@@ -280,8 +280,6 @@ impl Once {
     /// # Examples
     ///
     /// ```
-    /// #![feature(once_poison)]
-    ///
     /// use std::sync::Once;
     /// use std::thread;
     ///
@@ -301,13 +299,13 @@ impl Once {
     ///
     /// // call_once_force will still run and reset the poisoned state
     /// INIT.call_once_force(|state| {
-    ///     assert!(state.poisoned());
+    ///     assert!(state.is_poisoned());
     /// });
     ///
     /// // once any success happens, we stop propagating the poison
     /// INIT.call_once(|| {});
     /// ```
-    #[unstable(feature = "once_poison", issue = "33577")]
+    #[stable(feature = "once_poison", since = "1.51.0")]
     pub fn call_once_force<F>(&self, f: F)
     where
         F: FnOnce(&OnceState),
@@ -526,8 +524,6 @@ impl OnceState {
     /// A poisoned [`Once`]:
     ///
     /// ```
-    /// #![feature(once_poison)]
-    ///
     /// use std::sync::Once;
     /// use std::thread;
     ///
@@ -540,24 +536,22 @@ impl OnceState {
     /// assert!(handle.join().is_err());
     ///
     /// INIT.call_once_force(|state| {
-    ///     assert!(state.poisoned());
+    ///     assert!(state.is_poisoned());
     /// });
     /// ```
     ///
     /// An unpoisoned [`Once`]:
     ///
     /// ```
-    /// #![feature(once_poison)]
-    ///
     /// use std::sync::Once;
     ///
     /// static INIT: Once = Once::new();
     ///
     /// INIT.call_once_force(|state| {
-    ///     assert!(!state.poisoned());
+    ///     assert!(!state.is_poisoned());
     /// });
-    #[unstable(feature = "once_poison", issue = "33577")]
-    pub fn poisoned(&self) -> bool {
+    #[stable(feature = "once_poison", since = "1.51.0")]
+    pub fn is_poisoned(&self) -> bool {
         self.poisoned
     }
 
diff --git a/library/std/src/sync/once/tests.rs b/library/std/src/sync/once/tests.rs
index fae2752526e..0c35597e11c 100644
--- a/library/std/src/sync/once/tests.rs
+++ b/library/std/src/sync/once/tests.rs
@@ -69,7 +69,7 @@ fn poison_bad() {
     let mut called = false;
     O.call_once_force(|p| {
         called = true;
-        assert!(p.poisoned())
+        assert!(p.is_poisoned())
     });
     assert!(called);
 
@@ -92,7 +92,7 @@ fn wait_for_force_to_finish() {
     let (tx2, rx2) = channel();
     let t1 = thread::spawn(move || {
         O.call_once_force(|p| {
-            assert!(p.poisoned());
+            assert!(p.is_poisoned());
             tx1.send(()).unwrap();
             rx2.recv().unwrap();
         });
diff --git a/library/term/src/terminfo/parm/tests.rs b/library/term/src/terminfo/parm/tests.rs
index b975bd2d198..1cc0967c8f4 100644
--- a/library/term/src/terminfo/parm/tests.rs
+++ b/library/term/src/terminfo/parm/tests.rs
@@ -77,15 +77,15 @@ fn test_comparison_ops() {
     for &(op, bs) in v.iter() {
         let s = format!("%{{1}}%{{2}}%{}%d", op);
         let res = expand(s.as_bytes(), &[], &mut Variables::new());
-        assert!(res.is_ok(), res.unwrap_err());
+        assert!(res.is_ok(), "{}", res.unwrap_err());
         assert_eq!(res.unwrap(), vec![b'0' + bs[0]]);
         let s = format!("%{{1}}%{{1}}%{}%d", op);
         let res = expand(s.as_bytes(), &[], &mut Variables::new());
-        assert!(res.is_ok(), res.unwrap_err());
+        assert!(res.is_ok(), "{}", res.unwrap_err());
         assert_eq!(res.unwrap(), vec![b'0' + bs[1]]);
         let s = format!("%{{2}}%{{1}}%{}%d", op);
         let res = expand(s.as_bytes(), &[], &mut Variables::new());
-        assert!(res.is_ok(), res.unwrap_err());
+        assert!(res.is_ok(), "{}", res.unwrap_err());
         assert_eq!(res.unwrap(), vec![b'0' + bs[2]]);
     }
 }
@@ -95,13 +95,13 @@ fn test_conditionals() {
     let mut vars = Variables::new();
     let s = b"\\E[%?%p1%{8}%<%t3%p1%d%e%p1%{16}%<%t9%p1%{8}%-%d%e38;5;%p1%d%;m";
     let res = expand(s, &[Number(1)], &mut vars);
-    assert!(res.is_ok(), res.unwrap_err());
+    assert!(res.is_ok(), "{}", res.unwrap_err());
     assert_eq!(res.unwrap(), "\\E[31m".bytes().collect::<Vec<_>>());
     let res = expand(s, &[Number(8)], &mut vars);
-    assert!(res.is_ok(), res.unwrap_err());
+    assert!(res.is_ok(), "{}", res.unwrap_err());
     assert_eq!(res.unwrap(), "\\E[90m".bytes().collect::<Vec<_>>());
     let res = expand(s, &[Number(42)], &mut vars);
-    assert!(res.is_ok(), res.unwrap_err());
+    assert!(res.is_ok(), "{}", res.unwrap_err());
     assert_eq!(res.unwrap(), "\\E[38;5;42m".bytes().collect::<Vec<_>>());
 }
 
diff --git a/library/test/src/tests.rs b/library/test/src/tests.rs
index 99e12c973c4..f0586d510db 100644
--- a/library/test/src/tests.rs
+++ b/library/test/src/tests.rs
@@ -199,7 +199,7 @@ fn test_should_panic_bad_message() {
 fn test_should_panic_non_string_message_type() {
     use crate::tests::TrFailedMsg;
     fn f() {
-        panic!(1i32);
+        std::panic::panic_any(1i32);
     }
     let expected = "foobar";
     let failed_msg = format!(
diff --git a/src/test/ui-fulldeps/issue-15149.rs b/src/test/ui-fulldeps/issue-15149.rs
index c80628aabc8..c7ef5ad70a1 100644
--- a/src/test/ui-fulldeps/issue-15149.rs
+++ b/src/test/ui-fulldeps/issue-15149.rs
@@ -50,7 +50,7 @@ fn test() {
                                                       .output().unwrap();
 
     assert!(child_output.status.success(),
-            format!("child assertion failed\n child stdout:\n {}\n child stderr:\n {}",
-                    str::from_utf8(&child_output.stdout).unwrap(),
-                    str::from_utf8(&child_output.stderr).unwrap()));
+            "child assertion failed\n child stdout:\n {}\n child stderr:\n {}",
+            str::from_utf8(&child_output.stdout).unwrap(),
+            str::from_utf8(&child_output.stderr).unwrap());
 }
diff --git a/src/test/ui/async-await/issue-73137.rs b/src/test/ui/async-await/issue-73137.rs
index 18374460df7..c43ce2cadba 100644
--- a/src/test/ui/async-await/issue-73137.rs
+++ b/src/test/ui/async-await/issue-73137.rs
@@ -4,7 +4,6 @@
 // edition:2018
 
 #![allow(dead_code)]
-#![feature(wake_trait)]
 use std::future::Future;
 use std::task::{Waker, Wake, Context};
 use std::sync::Arc;
diff --git a/src/test/ui/consts/const-eval/const_panic.rs b/src/test/ui/consts/const-eval/const_panic.rs
index e9d66477d60..8ae8376ae4a 100644
--- a/src/test/ui/consts/const-eval/const_panic.rs
+++ b/src/test/ui/consts/const-eval/const_panic.rs
@@ -1,4 +1,5 @@
 #![feature(const_panic)]
+#![allow(non_fmt_panic)]
 #![crate_type = "lib"]
 
 const MSG: &str = "hello";
diff --git a/src/test/ui/consts/const-eval/const_panic.stderr b/src/test/ui/consts/const-eval/const_panic.stderr
index 713be5b662d..74907a0b495 100644
--- a/src/test/ui/consts/const-eval/const_panic.stderr
+++ b/src/test/ui/consts/const-eval/const_panic.stderr
@@ -1,10 +1,10 @@
 error: any use of this value will cause an error
-  --> $DIR/const_panic.rs:6:15
+  --> $DIR/const_panic.rs:7:15
    |
 LL | const Z: () = std::panic!("cheese");
    | --------------^^^^^^^^^^^^^^^^^^^^^-
    |               |
-   |               the evaluated program panicked at 'cheese', $DIR/const_panic.rs:6:15
+   |               the evaluated program panicked at 'cheese', $DIR/const_panic.rs:7:15
    |
    = note: `#[deny(const_err)]` on by default
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
@@ -12,108 +12,108 @@ LL | const Z: () = std::panic!("cheese");
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: any use of this value will cause an error
-  --> $DIR/const_panic.rs:10:16
+  --> $DIR/const_panic.rs:11:16
    |
 LL | const Z2: () = std::panic!();
    | ---------------^^^^^^^^^^^^^-
    |                |
-   |                the evaluated program panicked at 'explicit panic', $DIR/const_panic.rs:10:16
+   |                the evaluated program panicked at 'explicit panic', $DIR/const_panic.rs:11:16
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: any use of this value will cause an error
-  --> $DIR/const_panic.rs:14:15
+  --> $DIR/const_panic.rs:15:15
    |
 LL | const Y: () = std::unreachable!();
    | --------------^^^^^^^^^^^^^^^^^^^-
    |               |
-   |               the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic.rs:14:15
+   |               the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic.rs:15:15
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: any use of this value will cause an error
-  --> $DIR/const_panic.rs:18:15
+  --> $DIR/const_panic.rs:19:15
    |
 LL | const X: () = std::unimplemented!();
    | --------------^^^^^^^^^^^^^^^^^^^^^-
    |               |
-   |               the evaluated program panicked at 'not implemented', $DIR/const_panic.rs:18:15
+   |               the evaluated program panicked at 'not implemented', $DIR/const_panic.rs:19:15
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: any use of this value will cause an error
-  --> $DIR/const_panic.rs:22:15
+  --> $DIR/const_panic.rs:23:15
    |
 LL | const W: () = std::panic!(MSG);
    | --------------^^^^^^^^^^^^^^^^-
    |               |
-   |               the evaluated program panicked at 'hello', $DIR/const_panic.rs:22:15
+   |               the evaluated program panicked at 'hello', $DIR/const_panic.rs:23:15
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: any use of this value will cause an error
-  --> $DIR/const_panic.rs:26:20
+  --> $DIR/const_panic.rs:27:20
    |
 LL | const Z_CORE: () = core::panic!("cheese");
    | -------------------^^^^^^^^^^^^^^^^^^^^^^-
    |                    |
-   |                    the evaluated program panicked at 'cheese', $DIR/const_panic.rs:26:20
+   |                    the evaluated program panicked at 'cheese', $DIR/const_panic.rs:27:20
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: any use of this value will cause an error
-  --> $DIR/const_panic.rs:30:21
+  --> $DIR/const_panic.rs:31:21
    |
 LL | const Z2_CORE: () = core::panic!();
    | --------------------^^^^^^^^^^^^^^-
    |                     |
-   |                     the evaluated program panicked at 'explicit panic', $DIR/const_panic.rs:30:21
+   |                     the evaluated program panicked at 'explicit panic', $DIR/const_panic.rs:31:21
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: any use of this value will cause an error
-  --> $DIR/const_panic.rs:34:20
+  --> $DIR/const_panic.rs:35:20
    |
 LL | const Y_CORE: () = core::unreachable!();
    | -------------------^^^^^^^^^^^^^^^^^^^^-
    |                    |
-   |                    the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic.rs:34:20
+   |                    the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic.rs:35:20
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: any use of this value will cause an error
-  --> $DIR/const_panic.rs:38:20
+  --> $DIR/const_panic.rs:39:20
    |
 LL | const X_CORE: () = core::unimplemented!();
    | -------------------^^^^^^^^^^^^^^^^^^^^^^-
    |                    |
-   |                    the evaluated program panicked at 'not implemented', $DIR/const_panic.rs:38:20
+   |                    the evaluated program panicked at 'not implemented', $DIR/const_panic.rs:39:20
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: any use of this value will cause an error
-  --> $DIR/const_panic.rs:42:20
+  --> $DIR/const_panic.rs:43:20
    |
 LL | const W_CORE: () = core::panic!(MSG);
    | -------------------^^^^^^^^^^^^^^^^^-
    |                    |
-   |                    the evaluated program panicked at 'hello', $DIR/const_panic.rs:42:20
+   |                    the evaluated program panicked at 'hello', $DIR/const_panic.rs:43:20
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
diff --git a/src/test/ui/drop/dynamic-drop-async.rs b/src/test/ui/drop/dynamic-drop-async.rs
index a952fe8e76e..cb6d58a23d9 100644
--- a/src/test/ui/drop/dynamic-drop-async.rs
+++ b/src/test/ui/drop/dynamic-drop-async.rs
@@ -82,7 +82,7 @@ impl Allocator {
         self.cur_ops.set(self.cur_ops.get() + 1);
 
         if self.cur_ops.get() == self.failing_op {
-            panic!(InjectedFailure);
+            panic::panic_any(InjectedFailure);
         }
     }
 }
diff --git a/src/test/ui/drop/dynamic-drop.rs b/src/test/ui/drop/dynamic-drop.rs
index ddccee20e12..e28bedb982d 100644
--- a/src/test/ui/drop/dynamic-drop.rs
+++ b/src/test/ui/drop/dynamic-drop.rs
@@ -46,7 +46,7 @@ impl Allocator {
         self.cur_ops.set(self.cur_ops.get() + 1);
 
         if self.cur_ops.get() == self.failing_op {
-            panic!(InjectedFailure);
+            panic::panic_any(InjectedFailure);
         }
 
         let mut data = self.data.borrow_mut();
@@ -67,7 +67,7 @@ impl<'a> Drop for Ptr<'a> {
         self.1.cur_ops.set(self.1.cur_ops.get() + 1);
 
         if self.1.cur_ops.get() == self.1.failing_op {
-            panic!(InjectedFailure);
+            panic::panic_any(InjectedFailure);
         }
     }
 }
diff --git a/src/test/ui/fmt/format-args-capture.rs b/src/test/ui/fmt/format-args-capture.rs
index 4e3fa9a3c58..d5886a13558 100644
--- a/src/test/ui/fmt/format-args-capture.rs
+++ b/src/test/ui/fmt/format-args-capture.rs
@@ -31,7 +31,7 @@ fn panic_with_single_argument_does_not_get_formatted() {
     // RFC #2795 suggests that this may need to change so that captured arguments are formatted.
     // For stability reasons this will need to part of an edition change.
 
-    #[allow(panic_fmt)]
+    #[allow(non_fmt_panic)]
     let msg = std::panic::catch_unwind(|| {
         panic!("{foo}");
     }).unwrap_err();
diff --git a/src/test/ui/lint/forbid-group-group-1.rs b/src/test/ui/lint/forbid-group-group-1.rs
new file mode 100644
index 00000000000..80f7db4e560
--- /dev/null
+++ b/src/test/ui/lint/forbid-group-group-1.rs
@@ -0,0 +1,13 @@
+// Check what happens when we forbid a smaller group but
+// then allow a superset of that group.
+
+#![forbid(nonstandard_style)]
+
+// FIXME: Arguably this should be an error, but the WARNINGS group is
+// treated in a very special (and rather ad-hoc) way and
+// it fails to trigger.
+#[allow(warnings)]
+fn main() {
+    let A: ();
+    //~^ ERROR should have a snake case name
+}
diff --git a/src/test/ui/lint/forbid-group-group-1.stderr b/src/test/ui/lint/forbid-group-group-1.stderr
new file mode 100644
index 00000000000..fd425e5f74e
--- /dev/null
+++ b/src/test/ui/lint/forbid-group-group-1.stderr
@@ -0,0 +1,15 @@
+error: variable `A` should have a snake case name
+  --> $DIR/forbid-group-group-1.rs:11:9
+   |
+LL |     let A: ();
+   |         ^ help: convert the identifier to snake case: `a`
+   |
+note: the lint level is defined here
+  --> $DIR/forbid-group-group-1.rs:4:11
+   |
+LL | #![forbid(nonstandard_style)]
+   |           ^^^^^^^^^^^^^^^^^
+   = note: `#[forbid(non_snake_case)]` implied by `#[forbid(nonstandard_style)]`
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/lint/forbid-group-group-2.rs b/src/test/ui/lint/forbid-group-group-2.rs
new file mode 100644
index 00000000000..b12fd72da74
--- /dev/null
+++ b/src/test/ui/lint/forbid-group-group-2.rs
@@ -0,0 +1,26 @@
+// Check what happens when we forbid a bigger group but
+// then deny a subset of that group.
+
+#![forbid(warnings)]
+#![deny(forbidden_lint_groups)]
+
+#[allow(nonstandard_style)]
+//~^ ERROR incompatible with previous
+//~| WARNING previously accepted by the compiler
+//~| ERROR incompatible with previous
+//~| WARNING previously accepted by the compiler
+//~| ERROR incompatible with previous
+//~| WARNING previously accepted by the compiler
+//~| ERROR incompatible with previous
+//~| WARNING previously accepted by the compiler
+//~| ERROR incompatible with previous
+//~| WARNING previously accepted by the compiler
+//~| ERROR incompatible with previous
+//~| WARNING previously accepted by the compiler
+//~| ERROR incompatible with previous
+//~| WARNING previously accepted by the compiler
+//~| ERROR incompatible with previous
+//~| WARNING previously accepted by the compiler
+//~| ERROR incompatible with previous
+//~| WARNING previously accepted by the compiler
+fn main() {}
diff --git a/src/test/ui/lint/forbid-group-group-2.stderr b/src/test/ui/lint/forbid-group-group-2.stderr
new file mode 100644
index 00000000000..214e949c11a
--- /dev/null
+++ b/src/test/ui/lint/forbid-group-group-2.stderr
@@ -0,0 +1,115 @@
+error: allow(nonstandard_style) incompatible with previous forbid
+  --> $DIR/forbid-group-group-2.rs:7:9
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+...
+LL | #[allow(nonstandard_style)]
+   |         ^^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+note: the lint level is defined here
+  --> $DIR/forbid-group-group-2.rs:5:9
+   |
+LL | #![deny(forbidden_lint_groups)]
+   |         ^^^^^^^^^^^^^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+error: allow(nonstandard_style) incompatible with previous forbid
+  --> $DIR/forbid-group-group-2.rs:7:9
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+...
+LL | #[allow(nonstandard_style)]
+   |         ^^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+error: allow(nonstandard_style) incompatible with previous forbid
+  --> $DIR/forbid-group-group-2.rs:7:9
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+...
+LL | #[allow(nonstandard_style)]
+   |         ^^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+error: allow(nonstandard_style) incompatible with previous forbid
+  --> $DIR/forbid-group-group-2.rs:7:9
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+...
+LL | #[allow(nonstandard_style)]
+   |         ^^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+error: allow(nonstandard_style) incompatible with previous forbid
+  --> $DIR/forbid-group-group-2.rs:7:9
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+...
+LL | #[allow(nonstandard_style)]
+   |         ^^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+error: allow(nonstandard_style) incompatible with previous forbid
+  --> $DIR/forbid-group-group-2.rs:7:9
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+...
+LL | #[allow(nonstandard_style)]
+   |         ^^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+error: allow(nonstandard_style) incompatible with previous forbid
+  --> $DIR/forbid-group-group-2.rs:7:9
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+...
+LL | #[allow(nonstandard_style)]
+   |         ^^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+error: allow(nonstandard_style) incompatible with previous forbid
+  --> $DIR/forbid-group-group-2.rs:7:9
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+...
+LL | #[allow(nonstandard_style)]
+   |         ^^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+error: allow(nonstandard_style) incompatible with previous forbid
+  --> $DIR/forbid-group-group-2.rs:7:9
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+...
+LL | #[allow(nonstandard_style)]
+   |         ^^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+error: aborting due to 9 previous errors
+
diff --git a/src/test/ui/lint/forbid-group-member.rs b/src/test/ui/lint/forbid-group-member.rs
new file mode 100644
index 00000000000..6f1b2e9f668
--- /dev/null
+++ b/src/test/ui/lint/forbid-group-member.rs
@@ -0,0 +1,19 @@
+// Check what happens when we forbid a group but
+// then allow a member of that group.
+//
+// check-pass
+
+#![forbid(unused)]
+
+#[allow(unused_variables)]
+//~^ WARNING incompatible with previous forbid
+//~| WARNING previously accepted
+//~| WARNING incompatible with previous forbid
+//~| WARNING previously accepted
+//~| WARNING incompatible with previous forbid
+//~| WARNING previously accepted
+//~| WARNING incompatible with previous forbid
+//~| WARNING previously accepted
+fn main() {
+    let a: ();
+}
diff --git a/src/test/ui/lint/forbid-group-member.stderr b/src/test/ui/lint/forbid-group-member.stderr
new file mode 100644
index 00000000000..c818d7ff606
--- /dev/null
+++ b/src/test/ui/lint/forbid-group-member.stderr
@@ -0,0 +1,51 @@
+warning: allow(unused_variables) incompatible with previous forbid
+  --> $DIR/forbid-group-member.rs:8:9
+   |
+LL | #![forbid(unused)]
+   |           ------ `forbid` level set here
+LL | 
+LL | #[allow(unused_variables)]
+   |         ^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = note: `#[warn(forbidden_lint_groups)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+warning: allow(unused_variables) incompatible with previous forbid
+  --> $DIR/forbid-group-member.rs:8:9
+   |
+LL | #![forbid(unused)]
+   |           ------ `forbid` level set here
+LL | 
+LL | #[allow(unused_variables)]
+   |         ^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+warning: allow(unused_variables) incompatible with previous forbid
+  --> $DIR/forbid-group-member.rs:8:9
+   |
+LL | #![forbid(unused)]
+   |           ------ `forbid` level set here
+LL | 
+LL | #[allow(unused_variables)]
+   |         ^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+warning: allow(unused_variables) incompatible with previous forbid
+  --> $DIR/forbid-group-member.rs:8:9
+   |
+LL | #![forbid(unused)]
+   |           ------ `forbid` level set here
+LL | 
+LL | #[allow(unused_variables)]
+   |         ^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+warning: 4 warnings emitted
+
diff --git a/src/test/ui/lint/forbid-member-group.rs b/src/test/ui/lint/forbid-member-group.rs
new file mode 100644
index 00000000000..3279029a9cb
--- /dev/null
+++ b/src/test/ui/lint/forbid-member-group.rs
@@ -0,0 +1,12 @@
+// Check what happens when we forbid a member of
+// a group but then allow the group.
+
+#![forbid(unused_variables)]
+
+#[allow(unused)]
+//~^ ERROR incompatible with previous forbid
+//~| ERROR incompatible with previous forbid
+//~| ERROR incompatible with previous forbid
+fn main() {
+    let a: ();
+}
diff --git a/src/test/ui/lint/forbid-member-group.stderr b/src/test/ui/lint/forbid-member-group.stderr
new file mode 100644
index 00000000000..1d8ab4d5edb
--- /dev/null
+++ b/src/test/ui/lint/forbid-member-group.stderr
@@ -0,0 +1,30 @@
+error[E0453]: allow(unused) incompatible with previous forbid
+  --> $DIR/forbid-member-group.rs:6:9
+   |
+LL | #![forbid(unused_variables)]
+   |           ---------------- `forbid` level set here
+LL | 
+LL | #[allow(unused)]
+   |         ^^^^^^ overruled by previous forbid
+
+error[E0453]: allow(unused) incompatible with previous forbid
+  --> $DIR/forbid-member-group.rs:6:9
+   |
+LL | #![forbid(unused_variables)]
+   |           ---------------- `forbid` level set here
+LL | 
+LL | #[allow(unused)]
+   |         ^^^^^^ overruled by previous forbid
+
+error[E0453]: allow(unused) incompatible with previous forbid
+  --> $DIR/forbid-member-group.rs:6:9
+   |
+LL | #![forbid(unused_variables)]
+   |           ---------------- `forbid` level set here
+LL | 
+LL | #[allow(unused)]
+   |         ^^^^^^ overruled by previous forbid
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0453`.
diff --git a/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.rs b/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.rs
index f725304cf29..05d7d924c8f 100644
--- a/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.rs
+++ b/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.rs
@@ -14,14 +14,17 @@
 
 // compile-flags: -Z deduplicate-diagnostics=yes
 
+#![forbid(forbidden_lint_groups)]
+
 fn forbid_first(num: i32) -> i32 {
     #![forbid(unused)]
     #![deny(unused)]
     //~^ ERROR: deny(unused) incompatible with previous forbid
+    //~| WARNING being phased out
+    //~| ERROR: deny(unused) incompatible with previous forbid
+    //~| WARNING being phased out
     #![warn(unused)]
-    //~^ ERROR: warn(unused) incompatible with previous forbid
     #![allow(unused)]
-    //~^ ERROR: allow(unused) incompatible with previous forbid
 
     num * num
 }
diff --git a/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.stderr b/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.stderr
index 9f107411c10..475410cecff 100644
--- a/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.stderr
+++ b/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.stderr
@@ -1,29 +1,29 @@
-error[E0453]: deny(unused) incompatible with previous forbid
-  --> $DIR/issue-70819-dont-override-forbid-in-same-scope.rs:19:13
+error: deny(unused) incompatible with previous forbid
+  --> $DIR/issue-70819-dont-override-forbid-in-same-scope.rs:21:13
    |
 LL |     #![forbid(unused)]
    |               ------ `forbid` level set here
 LL |     #![deny(unused)]
    |             ^^^^^^ overruled by previous forbid
+   |
+note: the lint level is defined here
+  --> $DIR/issue-70819-dont-override-forbid-in-same-scope.rs:17:11
+   |
+LL | #![forbid(forbidden_lint_groups)]
+   |           ^^^^^^^^^^^^^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
 
-error[E0453]: warn(unused) incompatible with previous forbid
+error: deny(unused) incompatible with previous forbid
   --> $DIR/issue-70819-dont-override-forbid-in-same-scope.rs:21:13
    |
 LL |     #![forbid(unused)]
    |               ------ `forbid` level set here
-...
-LL |     #![warn(unused)]
+LL |     #![deny(unused)]
    |             ^^^^^^ overruled by previous forbid
-
-error[E0453]: allow(unused) incompatible with previous forbid
-  --> $DIR/issue-70819-dont-override-forbid-in-same-scope.rs:23:14
    |
-LL |     #![forbid(unused)]
-   |               ------ `forbid` level set here
-...
-LL |     #![allow(unused)]
-   |              ^^^^^^ overruled by previous forbid
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0453`.
diff --git a/src/test/ui/lint/issue-80988.rs b/src/test/ui/lint/issue-80988.rs
new file mode 100644
index 00000000000..16a041928db
--- /dev/null
+++ b/src/test/ui/lint/issue-80988.rs
@@ -0,0 +1,16 @@
+// Regression test for #80988
+//
+// check-pass
+
+#![forbid(warnings)]
+
+#[deny(warnings)]
+//~^ WARNING incompatible with previous forbid
+//~| WARNING being phased out
+//~| WARNING incompatible with previous forbid
+//~| WARNING being phased out
+//~| WARNING incompatible with previous forbid
+//~| WARNING being phased out
+//~| WARNING incompatible with previous forbid
+//~| WARNING being phased out
+fn main() {}
diff --git a/src/test/ui/lint/issue-80988.stderr b/src/test/ui/lint/issue-80988.stderr
new file mode 100644
index 00000000000..4cae11f97c0
--- /dev/null
+++ b/src/test/ui/lint/issue-80988.stderr
@@ -0,0 +1,51 @@
+warning: deny(warnings) incompatible with previous forbid
+  --> $DIR/issue-80988.rs:7:8
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+LL | 
+LL | #[deny(warnings)]
+   |        ^^^^^^^^ overruled by previous forbid
+   |
+   = note: `#[warn(forbidden_lint_groups)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+warning: deny(warnings) incompatible with previous forbid
+  --> $DIR/issue-80988.rs:7:8
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+LL | 
+LL | #[deny(warnings)]
+   |        ^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+warning: deny(warnings) incompatible with previous forbid
+  --> $DIR/issue-80988.rs:7:8
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+LL | 
+LL | #[deny(warnings)]
+   |        ^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+warning: deny(warnings) incompatible with previous forbid
+  --> $DIR/issue-80988.rs:7:8
+   |
+LL | #![forbid(warnings)]
+   |           -------- `forbid` level set here
+LL | 
+LL | #[deny(warnings)]
+   |        ^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+warning: 4 warnings emitted
+
diff --git a/src/test/ui/lint/issue-81218.rs b/src/test/ui/lint/issue-81218.rs
new file mode 100644
index 00000000000..f02aa9040eb
--- /dev/null
+++ b/src/test/ui/lint/issue-81218.rs
@@ -0,0 +1,14 @@
+// Regression test for #81218
+//
+// check-pass
+
+#![forbid(warnings)]
+
+#[allow(unused_variables)]
+fn main() {
+    // We want to ensure that you don't get an error
+    // here. The idea is that a derive might generate
+    // code that would otherwise trigger the "unused variables"
+    // lint, but it is meant to be suppressed.
+    let x: ();
+}
diff --git a/src/test/ui/lint/outer-forbid.rs b/src/test/ui/lint/outer-forbid.rs
index d45848bf706..486ec3c4680 100644
--- a/src/test/ui/lint/outer-forbid.rs
+++ b/src/test/ui/lint/outer-forbid.rs
@@ -15,11 +15,16 @@
 // compile-flags: -Z deduplicate-diagnostics=yes
 
 #![forbid(unused, non_snake_case)]
+#![forbid(forbidden_lint_groups)]
 
 #[allow(unused_variables)] //~ ERROR incompatible with previous
+//~^ ERROR incompatible with previous
+//~| WARNING this was previously accepted by the compiler
+//~| WARNING this was previously accepted by the compiler
 fn foo() {}
 
 #[allow(unused)] //~ ERROR incompatible with previous
+//~^ WARNING this was previously accepted by the compiler
 fn bar() {}
 
 #[allow(nonstandard_style)] //~ ERROR incompatible with previous
diff --git a/src/test/ui/lint/outer-forbid.stderr b/src/test/ui/lint/outer-forbid.stderr
index c012c20697e..d69157a8bb3 100644
--- a/src/test/ui/lint/outer-forbid.stderr
+++ b/src/test/ui/lint/outer-forbid.stderr
@@ -1,23 +1,34 @@
-error[E0453]: allow(unused_variables) incompatible with previous forbid
-  --> $DIR/outer-forbid.rs:19:9
+error: allow(unused_variables) incompatible with previous forbid
+  --> $DIR/outer-forbid.rs:20:9
    |
 LL | #![forbid(unused, non_snake_case)]
    |           ------ `forbid` level set here
-LL | 
+...
 LL | #[allow(unused_variables)]
    |         ^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+note: the lint level is defined here
+  --> $DIR/outer-forbid.rs:18:11
+   |
+LL | #![forbid(forbidden_lint_groups)]
+   |           ^^^^^^^^^^^^^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
 
-error[E0453]: allow(unused) incompatible with previous forbid
-  --> $DIR/outer-forbid.rs:22:9
+error: allow(unused) incompatible with previous forbid
+  --> $DIR/outer-forbid.rs:26:9
    |
 LL | #![forbid(unused, non_snake_case)]
    |           ------ `forbid` level set here
 ...
 LL | #[allow(unused)]
    |         ^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
 
 error[E0453]: allow(nonstandard_style) incompatible with previous forbid
-  --> $DIR/outer-forbid.rs:25:9
+  --> $DIR/outer-forbid.rs:30:9
    |
 LL | #![forbid(unused, non_snake_case)]
    |                   -------------- `forbid` level set here
@@ -25,6 +36,18 @@ LL | #![forbid(unused, non_snake_case)]
 LL | #[allow(nonstandard_style)]
    |         ^^^^^^^^^^^^^^^^^ overruled by previous forbid
 
-error: aborting due to 3 previous errors
+error: allow(unused_variables) incompatible with previous forbid
+  --> $DIR/outer-forbid.rs:20:9
+   |
+LL | #![forbid(unused, non_snake_case)]
+   |           ------ `forbid` level set here
+...
+LL | #[allow(unused_variables)]
+   |         ^^^^^^^^^^^^^^^^ overruled by previous forbid
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #81670 <https://github.com/rust-lang/rust/issues/81670>
+
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0453`.
diff --git a/src/test/ui/macros/assert-macro-owned.rs b/src/test/ui/macros/assert-macro-owned.rs
index b50fe65c015..2846f2a1f83 100644
--- a/src/test/ui/macros/assert-macro-owned.rs
+++ b/src/test/ui/macros/assert-macro-owned.rs
@@ -2,6 +2,8 @@
 // error-pattern:panicked at 'test-assert-owned'
 // ignore-emscripten no processes
 
+#![allow(non_fmt_panic)]
+
 fn main() {
     assert!(false, "test-assert-owned".to_string());
 }
diff --git a/src/test/ui/macros/macro-comma-behavior-rpass.rs b/src/test/ui/macros/macro-comma-behavior-rpass.rs
index c46274d59b6..fd2c590ae5f 100644
--- a/src/test/ui/macros/macro-comma-behavior-rpass.rs
+++ b/src/test/ui/macros/macro-comma-behavior-rpass.rs
@@ -57,7 +57,7 @@ fn writeln_1arg() {
 //
 // (Example: Issue #48042)
 #[test]
-#[allow(panic_fmt)]
+#[allow(non_fmt_panic)]
 fn to_format_or_not_to_format() {
     // ("{}" is the easiest string to test because if this gets
     // sent to format_args!, it'll simply fail to compile.
diff --git a/src/test/ui/mir/mir_drop_order.rs b/src/test/ui/mir/mir_drop_order.rs
index 2949437b1e4..22c804abf5c 100644
--- a/src/test/ui/mir/mir_drop_order.rs
+++ b/src/test/ui/mir/mir_drop_order.rs
@@ -38,7 +38,7 @@ fn main() {
     assert_eq!(get(), vec![0, 2, 3, 1]);
 
     let _ = std::panic::catch_unwind(|| {
-        (d(4), &d(5), d(6), &d(7), panic!(InjectedFailure));
+        (d(4), &d(5), d(6), &d(7), panic::panic_any(InjectedFailure));
     });
 
     // here, the temporaries (5/7) live until the end of the
diff --git a/src/test/ui/panic-brace.rs b/src/test/ui/non-fmt-panic.rs
index 754dcc287d0..25c53316e12 100644
--- a/src/test/ui/panic-brace.rs
+++ b/src/test/ui/non-fmt-panic.rs
@@ -13,19 +13,27 @@ fn main() {
     core::panic!("Hello {}"); //~ WARN panic message contains an unused formatting placeholder
     assert!(false, "{:03x} {test} bla");
     //~^ WARN panic message contains unused formatting placeholders
+    assert!(false, S);
+    //~^ WARN panic message is not a string literal
     debug_assert!(false, "{{}} bla"); //~ WARN panic message contains braces
-    panic!(C); // No warning (yet)
-    panic!(S); // No warning (yet)
+    panic!(C); //~ WARN panic message is not a string literal
+    panic!(S); //~ WARN panic message is not a string literal
+    std::panic!(123); //~ WARN panic message is not a string literal
+    core::panic!(&*"abc"); //~ WARN panic message is not a string literal
     panic!(concat!("{", "}")); //~ WARN panic message contains an unused formatting placeholder
     panic!(concat!("{", "{")); //~ WARN panic message contains braces
 
     fancy_panic::fancy_panic!("test {} 123");
     //~^ WARN panic message contains an unused formatting placeholder
 
+    fancy_panic::fancy_panic!(S);
+    //~^ WARN panic message is not a string literal
+
     // Check that the lint only triggers for std::panic and core::panic,
     // not any panic macro:
     macro_rules! panic {
         ($e:expr) => ();
     }
     panic!("{}"); // OK
+    panic!(S); // OK
 }
diff --git a/src/test/ui/panic-brace.stderr b/src/test/ui/non-fmt-panic.stderr
index 93808891c3c..45187c518c4 100644
--- a/src/test/ui/panic-brace.stderr
+++ b/src/test/ui/non-fmt-panic.stderr
@@ -1,35 +1,35 @@
 warning: panic message contains a brace
-  --> $DIR/panic-brace.rs:11:29
+  --> $DIR/non-fmt-panic.rs:11:29
    |
 LL |     panic!("here's a brace: {");
    |                             ^
    |
-   = note: `#[warn(panic_fmt)]` on by default
-   = note: this message is not used as a format string, but will be in a future Rust edition
+   = note: `#[warn(non_fmt_panic)]` on by default
+   = note: this message is not used as a format string, but will be in Rust 2021
 help: add a "{}" format string to use the message literally
    |
 LL |     panic!("{}", "here's a brace: {");
    |            ^^^^^
 
 warning: panic message contains a brace
-  --> $DIR/panic-brace.rs:12:31
+  --> $DIR/non-fmt-panic.rs:12:31
    |
 LL |     std::panic!("another one: }");
    |                               ^
    |
-   = note: this message is not used as a format string, but will be in a future Rust edition
+   = note: this message is not used as a format string, but will be in Rust 2021
 help: add a "{}" format string to use the message literally
    |
 LL |     std::panic!("{}", "another one: }");
    |                 ^^^^^
 
 warning: panic message contains an unused formatting placeholder
-  --> $DIR/panic-brace.rs:13:25
+  --> $DIR/non-fmt-panic.rs:13:25
    |
 LL |     core::panic!("Hello {}");
    |                         ^^
    |
-   = note: this message is not used as a format string when given without arguments, but will be in a future Rust edition
+   = note: this message is not used as a format string when given without arguments, but will be in Rust 2021
 help: add the missing argument
    |
 LL |     core::panic!("Hello {}", ...);
@@ -40,12 +40,12 @@ LL |     core::panic!("{}", "Hello {}");
    |                  ^^^^^
 
 warning: panic message contains unused formatting placeholders
-  --> $DIR/panic-brace.rs:14:21
+  --> $DIR/non-fmt-panic.rs:14:21
    |
 LL |     assert!(false, "{:03x} {test} bla");
    |                     ^^^^^^ ^^^^^^
    |
-   = note: this message is not used as a format string when given without arguments, but will be in a future Rust edition
+   = note: this message is not used as a format string when given without arguments, but will be in Rust 2021
 help: add the missing arguments
    |
 LL |     assert!(false, "{:03x} {test} bla", ...);
@@ -55,25 +55,97 @@ help: or add a "{}" format string to use the message literally
 LL |     assert!(false, "{}", "{:03x} {test} bla");
    |                    ^^^^^
 
+warning: panic message is not a string literal
+  --> $DIR/non-fmt-panic.rs:16:20
+   |
+LL |     assert!(false, S);
+   |                    ^
+   |
+   = note: this is no longer accepted in Rust 2021
+help: add a "{}" format string to Display the message
+   |
+LL |     assert!(false, "{}", S);
+   |                    ^^^^^
+
 warning: panic message contains braces
-  --> $DIR/panic-brace.rs:16:27
+  --> $DIR/non-fmt-panic.rs:18:27
    |
 LL |     debug_assert!(false, "{{}} bla");
    |                           ^^^^
    |
-   = note: this message is not used as a format string, but will be in a future Rust edition
+   = note: this message is not used as a format string, but will be in Rust 2021
 help: add a "{}" format string to use the message literally
    |
 LL |     debug_assert!(false, "{}", "{{}} bla");
    |                          ^^^^^
 
+warning: panic message is not a string literal
+  --> $DIR/non-fmt-panic.rs:19:12
+   |
+LL |     panic!(C);
+   |            ^
+   |
+   = note: this is no longer accepted in Rust 2021
+help: add a "{}" format string to Display the message
+   |
+LL |     panic!("{}", C);
+   |            ^^^^^
+help: or use std::panic::panic_any instead
+   |
+LL |     std::panic::panic_any(C);
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: panic message is not a string literal
+  --> $DIR/non-fmt-panic.rs:20:12
+   |
+LL |     panic!(S);
+   |            ^
+   |
+   = note: this is no longer accepted in Rust 2021
+help: add a "{}" format string to Display the message
+   |
+LL |     panic!("{}", S);
+   |            ^^^^^
+help: or use std::panic::panic_any instead
+   |
+LL |     std::panic::panic_any(S);
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: panic message is not a string literal
+  --> $DIR/non-fmt-panic.rs:21:17
+   |
+LL |     std::panic!(123);
+   |                 ^^^
+   |
+   = note: this is no longer accepted in Rust 2021
+help: add a "{}" format string to Display the message
+   |
+LL |     std::panic!("{}", 123);
+   |                 ^^^^^
+help: or use std::panic::panic_any instead
+   |
+LL |     std::panic::panic_any(123);
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: panic message is not a string literal
+  --> $DIR/non-fmt-panic.rs:22:18
+   |
+LL |     core::panic!(&*"abc");
+   |                  ^^^^^^^
+   |
+   = note: this is no longer accepted in Rust 2021
+help: add a "{}" format string to Display the message
+   |
+LL |     core::panic!("{}", &*"abc");
+   |                  ^^^^^
+
 warning: panic message contains an unused formatting placeholder
-  --> $DIR/panic-brace.rs:19:12
+  --> $DIR/non-fmt-panic.rs:23:12
    |
 LL |     panic!(concat!("{", "}"));
    |            ^^^^^^^^^^^^^^^^^
    |
-   = note: this message is not used as a format string when given without arguments, but will be in a future Rust edition
+   = note: this message is not used as a format string when given without arguments, but will be in Rust 2021
 help: add the missing argument
    |
 LL |     panic!(concat!("{", "}"), ...);
@@ -84,24 +156,32 @@ LL |     panic!("{}", concat!("{", "}"));
    |            ^^^^^
 
 warning: panic message contains braces
-  --> $DIR/panic-brace.rs:20:5
+  --> $DIR/non-fmt-panic.rs:24:5
    |
 LL |     panic!(concat!("{", "{"));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: this message is not used as a format string, but will be in a future Rust edition
+   = note: this message is not used as a format string, but will be in Rust 2021
 help: add a "{}" format string to use the message literally
    |
 LL |     panic!("{}", concat!("{", "{"));
    |            ^^^^^
 
 warning: panic message contains an unused formatting placeholder
-  --> $DIR/panic-brace.rs:22:37
+  --> $DIR/non-fmt-panic.rs:26:37
    |
 LL |     fancy_panic::fancy_panic!("test {} 123");
    |                                     ^^
    |
-   = note: this message is not used as a format string when given without arguments, but will be in a future Rust edition
+   = note: this message is not used as a format string when given without arguments, but will be in Rust 2021
+
+warning: panic message is not a string literal
+  --> $DIR/non-fmt-panic.rs:29:31
+   |
+LL |     fancy_panic::fancy_panic!(S);
+   |                               ^
+   |
+   = note: this is no longer accepted in Rust 2021
 
-warning: 8 warnings emitted
+warning: 14 warnings emitted
 
diff --git a/src/test/ui/pattern/or-pattern-macro-pat.rs b/src/test/ui/or-patterns/macro-pat.rs
index 8749407675b..8749407675b 100644
--- a/src/test/ui/pattern/or-pattern-macro-pat.rs
+++ b/src/test/ui/or-patterns/macro-pat.rs
diff --git a/src/test/ui/panics/explicit-panic-msg.rs b/src/test/ui/panics/explicit-panic-msg.rs
index 1789e2e62c8..bfcc12cd186 100644
--- a/src/test/ui/panics/explicit-panic-msg.rs
+++ b/src/test/ui/panics/explicit-panic-msg.rs
@@ -1,5 +1,6 @@
 #![allow(unused_assignments)]
 #![allow(unused_variables)]
+#![allow(non_fmt_panic)]
 
 // run-fail
 // error-pattern:wooooo
diff --git a/src/test/ui/panics/panic-macro-any-wrapped.rs b/src/test/ui/panics/panic-macro-any-wrapped.rs
index 80c87c6f32c..95ae6ffe8be 100644
--- a/src/test/ui/panics/panic-macro-any-wrapped.rs
+++ b/src/test/ui/panics/panic-macro-any-wrapped.rs
@@ -2,6 +2,8 @@
 // error-pattern:panicked at 'Box<Any>'
 // ignore-emscripten no processes
 
+#![allow(non_fmt_panic)]
+
 fn main() {
     panic!(Box::new(612_i64));
 }
diff --git a/src/test/ui/panics/panic-macro-any.rs b/src/test/ui/panics/panic-macro-any.rs
index ffc7114c1f5..d2a7ba3713a 100644
--- a/src/test/ui/panics/panic-macro-any.rs
+++ b/src/test/ui/panics/panic-macro-any.rs
@@ -3,6 +3,7 @@
 // ignore-emscripten no processes
 
 #![feature(box_syntax)]
+#![allow(non_fmt_panic)]
 
 fn main() {
     panic!(box 413 as Box<dyn std::any::Any + Send>);
diff --git a/src/test/ui/panics/while-panic.rs b/src/test/ui/panics/while-panic.rs
index 857f65a2252..3c6ee8fa315 100644
--- a/src/test/ui/panics/while-panic.rs
+++ b/src/test/ui/panics/while-panic.rs
@@ -5,7 +5,7 @@
 // ignore-emscripten no processes
 
 fn main() {
-    panic!({
+    panic!("{}", {
         while true {
             panic!("giraffe")
         }
diff --git a/src/tools/clippy/clippy_lints/src/methods/mod.rs b/src/tools/clippy/clippy_lints/src/methods/mod.rs
index a17c5996293..4ee423b383b 100644
--- a/src/tools/clippy/clippy_lints/src/methods/mod.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/mod.rs
@@ -2183,7 +2183,7 @@ fn lint_expect_fun_call(
         span_replace_word,
         &format!("use of `{}` followed by a function call", name),
         "try this",
-        format!("unwrap_or_else({} {{ panic!({}) }})", closure_args, arg_root_snippet),
+        format!("unwrap_or_else({} {{ panic!(\"{{}}\", {}) }})", closure_args, arg_root_snippet),
         applicability,
     );
 }
diff --git a/src/tools/clippy/tests/missing-test-files.rs b/src/tools/clippy/tests/missing-test-files.rs
index d87bb4be3c3..9cef7438d22 100644
--- a/src/tools/clippy/tests/missing-test-files.rs
+++ b/src/tools/clippy/tests/missing-test-files.rs
@@ -9,14 +9,12 @@ fn test_missing_tests() {
     if !missing_files.is_empty() {
         assert!(
             false,
-            format!(
-                "Didn't see a test file for the following files:\n\n{}\n",
-                missing_files
-                    .iter()
-                    .map(|s| format!("\t{}", s))
-                    .collect::<Vec<_>>()
-                    .join("\n")
-            )
+            "Didn't see a test file for the following files:\n\n{}\n",
+            missing_files
+                .iter()
+                .map(|s| format!("\t{}", s))
+                .collect::<Vec<_>>()
+                .join("\n")
         );
     }
 }
diff --git a/src/tools/clippy/tests/ui/assertions_on_constants.rs b/src/tools/clippy/tests/ui/assertions_on_constants.rs
index 60d721c2f20..e989de65404 100644
--- a/src/tools/clippy/tests/ui/assertions_on_constants.rs
+++ b/src/tools/clippy/tests/ui/assertions_on_constants.rs
@@ -1,3 +1,5 @@
+#![allow(non_fmt_panic)]
+
 macro_rules! assert_const {
     ($len:expr) => {
         assert!($len > 0);
diff --git a/src/tools/clippy/tests/ui/assertions_on_constants.stderr b/src/tools/clippy/tests/ui/assertions_on_constants.stderr
index 8f09c8ce9d5..c66fdf093f5 100644
--- a/src/tools/clippy/tests/ui/assertions_on_constants.stderr
+++ b/src/tools/clippy/tests/ui/assertions_on_constants.stderr
@@ -1,5 +1,5 @@
 error: `assert!(true)` will be optimized out by the compiler
-  --> $DIR/assertions_on_constants.rs:9:5
+  --> $DIR/assertions_on_constants.rs:11:5
    |
 LL |     assert!(true);
    |     ^^^^^^^^^^^^^^
@@ -9,7 +9,7 @@ LL |     assert!(true);
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `assert!(false)` should probably be replaced
-  --> $DIR/assertions_on_constants.rs:10:5
+  --> $DIR/assertions_on_constants.rs:12:5
    |
 LL |     assert!(false);
    |     ^^^^^^^^^^^^^^^
@@ -18,7 +18,7 @@ LL |     assert!(false);
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `assert!(true)` will be optimized out by the compiler
-  --> $DIR/assertions_on_constants.rs:11:5
+  --> $DIR/assertions_on_constants.rs:13:5
    |
 LL |     assert!(true, "true message");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -27,7 +27,7 @@ LL |     assert!(true, "true message");
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `assert!(false, "false message")` should probably be replaced
-  --> $DIR/assertions_on_constants.rs:12:5
+  --> $DIR/assertions_on_constants.rs:14:5
    |
 LL |     assert!(false, "false message");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -36,7 +36,7 @@ LL |     assert!(false, "false message");
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `assert!(false, msg.to_uppercase())` should probably be replaced
-  --> $DIR/assertions_on_constants.rs:15:5
+  --> $DIR/assertions_on_constants.rs:17:5
    |
 LL |     assert!(false, msg.to_uppercase());
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -45,7 +45,7 @@ LL |     assert!(false, msg.to_uppercase());
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `assert!(true)` will be optimized out by the compiler
-  --> $DIR/assertions_on_constants.rs:18:5
+  --> $DIR/assertions_on_constants.rs:20:5
    |
 LL |     assert!(B);
    |     ^^^^^^^^^^^
@@ -54,7 +54,7 @@ LL |     assert!(B);
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `assert!(false)` should probably be replaced
-  --> $DIR/assertions_on_constants.rs:21:5
+  --> $DIR/assertions_on_constants.rs:23:5
    |
 LL |     assert!(C);
    |     ^^^^^^^^^^^
@@ -63,7 +63,7 @@ LL |     assert!(C);
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `assert!(false, "C message")` should probably be replaced
-  --> $DIR/assertions_on_constants.rs:22:5
+  --> $DIR/assertions_on_constants.rs:24:5
    |
 LL |     assert!(C, "C message");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -72,7 +72,7 @@ LL |     assert!(C, "C message");
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: `debug_assert!(true)` will be optimized out by the compiler
-  --> $DIR/assertions_on_constants.rs:24:5
+  --> $DIR/assertions_on_constants.rs:26:5
    |
 LL |     debug_assert!(true);
    |     ^^^^^^^^^^^^^^^^^^^^
diff --git a/src/tools/clippy/tests/ui/expect_fun_call.fixed b/src/tools/clippy/tests/ui/expect_fun_call.fixed
index f3d8a941a92..a756d1cf506 100644
--- a/src/tools/clippy/tests/ui/expect_fun_call.fixed
+++ b/src/tools/clippy/tests/ui/expect_fun_call.fixed
@@ -74,12 +74,12 @@ fn main() {
             "foo"
         }
 
-        Some("foo").unwrap_or_else(|| { panic!(get_string()) });
-        Some("foo").unwrap_or_else(|| { panic!(get_string()) });
-        Some("foo").unwrap_or_else(|| { panic!(get_string()) });
+        Some("foo").unwrap_or_else(|| { panic!("{}", get_string()) });
+        Some("foo").unwrap_or_else(|| { panic!("{}", get_string()) });
+        Some("foo").unwrap_or_else(|| { panic!("{}", get_string()) });
 
-        Some("foo").unwrap_or_else(|| { panic!(get_static_str()) });
-        Some("foo").unwrap_or_else(|| { panic!(get_non_static_str(&0).to_string()) });
+        Some("foo").unwrap_or_else(|| { panic!("{}", get_static_str()) });
+        Some("foo").unwrap_or_else(|| { panic!("{}", get_non_static_str(&0).to_string()) });
     }
 
     //Issue #3839
diff --git a/src/tools/clippy/tests/ui/expect_fun_call.stderr b/src/tools/clippy/tests/ui/expect_fun_call.stderr
index a492e2df89d..6dc796f5cee 100644
--- a/src/tools/clippy/tests/ui/expect_fun_call.stderr
+++ b/src/tools/clippy/tests/ui/expect_fun_call.stderr
@@ -34,31 +34,31 @@ error: use of `expect` followed by a function call
   --> $DIR/expect_fun_call.rs:77:21
    |
 LL |         Some("foo").expect(&get_string());
-   |                     ^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!(get_string()) })`
+   |                     ^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!("{}", get_string()) })`
 
 error: use of `expect` followed by a function call
   --> $DIR/expect_fun_call.rs:78:21
    |
 LL |         Some("foo").expect(get_string().as_ref());
-   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!(get_string()) })`
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!("{}", get_string()) })`
 
 error: use of `expect` followed by a function call
   --> $DIR/expect_fun_call.rs:79:21
    |
 LL |         Some("foo").expect(get_string().as_str());
-   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!(get_string()) })`
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!("{}", get_string()) })`
 
 error: use of `expect` followed by a function call
   --> $DIR/expect_fun_call.rs:81:21
    |
 LL |         Some("foo").expect(get_static_str());
-   |                     ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!(get_static_str()) })`
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!("{}", get_static_str()) })`
 
 error: use of `expect` followed by a function call
   --> $DIR/expect_fun_call.rs:82:21
    |
 LL |         Some("foo").expect(get_non_static_str(&0));
-   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!(get_non_static_str(&0).to_string()) })`
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| { panic!("{}", get_non_static_str(&0).to_string()) })`
 
 error: use of `expect` followed by a function call
   --> $DIR/expect_fun_call.rs:86:16
diff --git a/src/tools/clippy/tests/ui/fallible_impl_from.rs b/src/tools/clippy/tests/ui/fallible_impl_from.rs
index 679f4a7dc35..5d5af4e4632 100644
--- a/src/tools/clippy/tests/ui/fallible_impl_from.rs
+++ b/src/tools/clippy/tests/ui/fallible_impl_from.rs
@@ -36,7 +36,7 @@ impl From<Option<String>> for Invalid {
     fn from(s: Option<String>) -> Invalid {
         let s = s.unwrap();
         if !s.is_empty() {
-            panic!(42);
+            panic!("42");
         } else if s.parse::<u32>().unwrap() != 42 {
             panic!("{:?}", s);
         }
diff --git a/src/tools/clippy/tests/ui/fallible_impl_from.stderr b/src/tools/clippy/tests/ui/fallible_impl_from.stderr
index ab976b947b3..f787b30bdab 100644
--- a/src/tools/clippy/tests/ui/fallible_impl_from.stderr
+++ b/src/tools/clippy/tests/ui/fallible_impl_from.stderr
@@ -59,8 +59,8 @@ note: potential failure(s)
 LL |         let s = s.unwrap();
    |                 ^^^^^^^^^^
 LL |         if !s.is_empty() {
-LL |             panic!(42);
-   |             ^^^^^^^^^^^
+LL |             panic!("42");
+   |             ^^^^^^^^^^^^^
 LL |         } else if s.parse::<u32>().unwrap() != 42 {
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^
 LL |             panic!("{:?}", s);