Auto merge of #83213 - rylev:update-lints-to-errors, r=nikomatsakis

Update BARE_TRAIT_OBJECT and ELLIPSIS_INCLUSIVE_RANGE_PATTERNS to errors in Rust 2021

This addresses https://github.com/rust-lang/rust/pull/81244 by updating two lints to errors in the Rust 2021 edition.

r? `@estebank`

8 files changed, 176 insertions, 54 deletions

diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index e7c566e586c..32320130b67 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -46,7 +46,7 @@ use rustc_ast_pretty::pprust;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::sync::Lrc;
-use rustc_errors::struct_span_err;
+use rustc_errors::{struct_span_err, Applicability};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Namespace, PartialRes, PerNS, Res};
 use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId, CRATE_DEF_ID};
@@ -58,6 +58,7 @@ use rustc_session::lint::builtin::{BARE_TRAIT_OBJECTS, MISSING_ABI};
 use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
 use rustc_session::utils::{FlattenNonterminals, NtToTokenstream};
 use rustc_session::Session;
+use rustc_span::edition::Edition;
 use rustc_span::hygiene::ExpnId;
 use rustc_span::source_map::{respan, DesugaringKind};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
@@ -2730,13 +2731,26 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             .map(|snippet| snippet.starts_with("#["))
             .unwrap_or(true);
         if !is_macro_callsite {
-            self.resolver.lint_buffer().buffer_lint_with_diagnostic(
-                BARE_TRAIT_OBJECTS,
-                id,
-                span,
-                "trait objects without an explicit `dyn` are deprecated",
-                BuiltinLintDiagnostics::BareTraitObject(span, is_global),
-            )
+            if span.edition() < Edition::Edition2021 {
+                self.resolver.lint_buffer().buffer_lint_with_diagnostic(
+                    BARE_TRAIT_OBJECTS,
+                    id,
+                    span,
+                    "trait objects without an explicit `dyn` are deprecated",
+                    BuiltinLintDiagnostics::BareTraitObject(span, is_global),
+                )
+            } else {
+                let msg = "trait objects must include the `dyn` keyword";
+                let label = "add `dyn` keyword before this trait";
+                let mut err = struct_span_err!(self.sess, span, E0782, "{}", msg,);
+                err.span_suggestion_verbose(
+                    span.shrink_to_lo(),
+                    label,
+                    String::from("dyn "),
+                    Applicability::MachineApplicable,
+                );
+                err.emit();
+            }
         }
     }
 
diff --git a/compiler/rustc_error_codes/src/error_codes.rs b/compiler/rustc_error_codes/src/error_codes.rs
index 41a1fa488d3..c343809179b 100644
--- a/compiler/rustc_error_codes/src/error_codes.rs
+++ b/compiler/rustc_error_codes/src/error_codes.rs
@@ -470,6 +470,8 @@ E0778: include_str!("./error_codes/E0778.md"),
 E0779: include_str!("./error_codes/E0779.md"),
 E0780: include_str!("./error_codes/E0780.md"),
 E0781: include_str!("./error_codes/E0781.md"),
+E0782: include_str!("./error_codes/E0782.md"),
+E0783: include_str!("./error_codes/E0783.md"),
 ;
 //  E0006, // merged with E0005
 //  E0008, // cannot bind by-move into a pattern guard
diff --git a/compiler/rustc_error_codes/src/error_codes/E0782.md b/compiler/rustc_error_codes/src/error_codes/E0782.md
new file mode 100644
index 00000000000..0f3253c050e
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0782.md
@@ -0,0 +1,26 @@
+Trait objects must include the `dyn` keyword.
+
+Erroneous code example:
+
+```edition2021,compile_fail,E0782
+trait Foo {}
+fn test(arg: Box<Foo>) {} // error!
+```
+
+Trait objects are a way to call methods on types that are not known until
+runtime but conform to some trait.
+
+Trait objects should be formed with `Box<dyn Foo>`, but in the code above
+`dyn` is left off.
+
+This makes it harder to see that `arg` is a trait object and not a
+simply a heap allocated type called `Foo`.
+
+To fix this issue, add `dyn` before the trait name.
+
+```edition2021
+trait Foo {}
+fn test(arg: Box<dyn Foo>) {} // ok!
+```
+
+This used to be allowed before edition 2021, but is now an error.
diff --git a/compiler/rustc_error_codes/src/error_codes/E0783.md b/compiler/rustc_error_codes/src/error_codes/E0783.md
new file mode 100644
index 00000000000..73981e59e0d
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0783.md
@@ -0,0 +1,22 @@
+The range pattern `...` is no longer allowed.
+
+Erroneous code example:
+
+```edition2021,compile_fail,E0783
+match 2u8 {
+    0...9 => println!("Got a number less than 10"), // error!
+    _ => println!("Got a number 10 or more"),
+}
+```
+
+Older Rust code using previous editions allowed `...` to stand for exclusive
+ranges which are now signified using `..=`.
+
+To make this code compile replace the `...` with `..=`.
+
+```edition2021
+match 2u8 {
+    0..=9 => println!("Got a number less than 10"), // ok!
+    _ => println!("Got a number 10 or more"),
+}
+```
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index c9b038f0e87..e7275374b89 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -1660,7 +1660,11 @@ declare_lint! {
     /// [`..` range expression]: https://doc.rust-lang.org/reference/expressions/range-expr.html
     pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
     Warn,
-    "`...` range patterns are deprecated"
+    "`...` range patterns are deprecated",
+    @future_incompatible = FutureIncompatibleInfo {
+        reference: "issue #80165 <https://github.com/rust-lang/rust/issues/80165>",
+        edition: Some(Edition::Edition2021),
+    };
 }
 
 #[derive(Default)]
@@ -1704,32 +1708,57 @@ impl EarlyLintPass for EllipsisInclusiveRangePatterns {
             let suggestion = "use `..=` for an inclusive range";
             if parenthesise {
                 self.node_id = Some(pat.id);
-                cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, pat.span, |lint| {
-                    let end = expr_to_string(&end);
-                    let replace = match start {
-                        Some(start) => format!("&({}..={})", expr_to_string(&start), end),
-                        None => format!("&(..={})", end),
-                    };
-                    lint.build(msg)
-                        .span_suggestion(
-                            pat.span,
-                            suggestion,
-                            replace,
-                            Applicability::MachineApplicable,
-                        )
-                        .emit();
-                });
+                let end = expr_to_string(&end);
+                let replace = match start {
+                    Some(start) => format!("&({}..={})", expr_to_string(&start), end),
+                    None => format!("&(..={})", end),
+                };
+                if join.edition() >= Edition::Edition2021 {
+                    let mut err =
+                        rustc_errors::struct_span_err!(cx.sess, pat.span, E0783, "{}", msg,);
+                    err.span_suggestion(
+                        pat.span,
+                        suggestion,
+                        replace,
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();
+                } else {
+                    cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, pat.span, |lint| {
+                        lint.build(msg)
+                            .span_suggestion(
+                                pat.span,
+                                suggestion,
+                                replace,
+                                Applicability::MachineApplicable,
+                            )
+                            .emit();
+                    });
+                }
             } else {
-                cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, join, |lint| {
-                    lint.build(msg)
-                        .span_suggestion_short(
-                            join,
-                            suggestion,
-                            "..=".to_owned(),
-                            Applicability::MachineApplicable,
-                        )
-                        .emit();
-                });
+                let replace = "..=".to_owned();
+                if join.edition() >= Edition::Edition2021 {
+                    let mut err =
+                        rustc_errors::struct_span_err!(cx.sess, pat.span, E0783, "{}", msg,);
+                    err.span_suggestion_short(
+                        join,
+                        suggestion,
+                        replace,
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();
+                } else {
+                    cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, join, |lint| {
+                        lint.build(msg)
+                            .span_suggestion_short(
+                                join,
+                                suggestion,
+                                replace,
+                                Applicability::MachineApplicable,
+                            )
+                            .emit();
+                    });
+                }
             };
         }
     }
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 04e45e2351b..beb4d36597c 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -1618,7 +1618,11 @@ declare_lint! {
     /// [`impl Trait`]: https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
     pub BARE_TRAIT_OBJECTS,
     Warn,
-    "suggest using `dyn Trait` for trait objects"
+    "suggest using `dyn Trait` for trait objects",
+    @future_incompatible = FutureIncompatibleInfo {
+        reference: "issue #80165 <https://github.com/rust-lang/rust/issues/80165>",
+        edition: Some(Edition::Edition2021),
+    };
 }
 
 declare_lint! {
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index 26e61ec8cf8..7adaf54fa23 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/compiler/rustc_middle/src/lint.rs
@@ -272,11 +272,13 @@ pub fn struct_lint_level<'s, 'd>(
             // emit shouldn't be automatically fixed by rustfix.
             err.allow_suggestions(false);
 
-            // If this is a future incompatible lint it'll become a hard error, so
-            // we have to emit *something*. Also, if this lint occurs in the
-            // expansion of a macro from an external crate, allow individual lints
-            // to opt-out from being reported.
-            if future_incompatible.is_none() && !lint.report_in_external_macro {
+            // If this is a future incompatible that is not an edition fixing lint
+            // it'll become a hard error, so we have to emit *something*. Also,
+            // if this lint occurs in the expansion of a macro from an external crate,
+            // allow individual lints to opt-out from being reported.
+            let not_future_incompatible =
+                future_incompatible.map(|f| f.edition.is_some()).unwrap_or(true);
+            if not_future_incompatible && !lint.report_in_external_macro {
                 err.cancel();
                 // Don't continue further, since we don't want to have
                 // `diag_span_note_once` called for a diagnostic that isn't emitted.
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
index 1959fe75e8e..0c6a33b91ce 100644
--- a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
@@ -30,6 +30,7 @@ use rustc_middle::ty::{
 use rustc_session::lint;
 use rustc_session::lint::builtin::BARE_TRAIT_OBJECTS;
 use rustc_session::parse::feature_err;
+use rustc_span::edition::Edition;
 use rustc_span::source_map::{original_sp, DUMMY_SP};
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{self, BytePos, MultiSpan, Span};
@@ -969,20 +970,42 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             if let TyKind::TraitObject([poly_trait_ref, ..], _, TraitObjectSyntax::None) =
                 self_ty.kind
             {
-                self.tcx.struct_span_lint_hir(BARE_TRAIT_OBJECTS, hir_id, self_ty.span, |lint| {
-                    let mut db = lint
-                        .build(&format!("trait objects without an explicit `dyn` are deprecated"));
-                    let (sugg, app) = match self.tcx.sess.source_map().span_to_snippet(self_ty.span)
-                    {
-                        Ok(s) if poly_trait_ref.trait_ref.path.is_global() => {
-                            (format!("<dyn ({})>", s), Applicability::MachineApplicable)
-                        }
-                        Ok(s) => (format!("<dyn {}>", s), Applicability::MachineApplicable),
-                        Err(_) => ("<dyn <type>>".to_string(), Applicability::HasPlaceholders),
-                    };
-                    db.span_suggestion(self_ty.span, "use `dyn`", sugg, app);
-                    db.emit()
-                });
+                let msg = "trait objects without an explicit `dyn` are deprecated";
+                let (sugg, app) = match self.tcx.sess.source_map().span_to_snippet(self_ty.span) {
+                    Ok(s) if poly_trait_ref.trait_ref.path.is_global() => {
+                        (format!("<dyn ({})>", s), Applicability::MachineApplicable)
+                    }
+                    Ok(s) => (format!("<dyn {}>", s), Applicability::MachineApplicable),
+                    Err(_) => ("<dyn <type>>".to_string(), Applicability::HasPlaceholders),
+                };
+                let replace = String::from("use `dyn`");
+                if self.sess().edition() >= Edition::Edition2021 {
+                    let mut err = rustc_errors::struct_span_err!(
+                        self.sess(),
+                        self_ty.span,
+                        E0783,
+                        "{}",
+                        msg,
+                    );
+                    err.span_suggestion(
+                        self_ty.span,
+                        &sugg,
+                        replace,
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();
+                } else {
+                    self.tcx.struct_span_lint_hir(
+                        BARE_TRAIT_OBJECTS,
+                        hir_id,
+                        self_ty.span,
+                        |lint| {
+                            let mut db = lint.build(msg);
+                            db.span_suggestion(self_ty.span, &replace, sugg, app);
+                            db.emit()
+                        },
+                    );
+                }
             }
         }
     }