Auto merge of #93548 - matthiaskrgr:rollup-f7dkn3p, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #86374 (Enable combining `+crt-static` and `relocation-model=pic` on `x86_64-unknown-linux-gnu`)
 - #91828 (Implement `RawWaker` and `Waker` getters for underlying pointers)
 - #92021 (Eliminate duplicate codes of is_single_fp_element)
 - #92584 (add rustc lint, warning when iterating over hashmaps 2)
 - #93267 (implement a lint for suspicious auto trait impls)
 - #93290 (remove `TyS::same_type`)
 - #93436 (Update compiler_builtins to fix duplicate symbols in `armv7-linux-androideabi` rlib)

Failed merges:

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

51 files changed, 526 insertions, 165 deletions

diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index f21f0b895ad..a594339296f 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -34,6 +34,7 @@
 #![feature(box_patterns)]
 #![feature(never_type)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 use rustc_ast::token::{self, Token};
 use rustc_ast::tokenstream::{CanSynthesizeMissingTokens, TokenStream, TokenTree};
diff --git a/compiler/rustc_ast_passes/src/lib.rs b/compiler/rustc_ast_passes/src/lib.rs
index adc4d117b80..f4863137bdd 100644
--- a/compiler/rustc_ast_passes/src/lib.rs
+++ b/compiler/rustc_ast_passes/src/lib.rs
@@ -8,6 +8,7 @@
 #![feature(box_patterns)]
 #![feature(let_else)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 pub mod ast_validation;
 pub mod feature_gate;
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 1e9acb114b7..c288cc96990 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -9,6 +9,7 @@
 #![feature(trusted_step)]
 #![feature(try_blocks)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_middle;
diff --git a/compiler/rustc_builtin_macros/src/lib.rs b/compiler/rustc_builtin_macros/src/lib.rs
index 6c16c285492..eda9be58d94 100644
--- a/compiler/rustc_builtin_macros/src/lib.rs
+++ b/compiler/rustc_builtin_macros/src/lib.rs
@@ -12,6 +12,7 @@
 #![feature(proc_macro_internals)]
 #![feature(proc_macro_quote)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 extern crate proc_macro;
 
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index f0612eaba80..75836e14385 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -11,6 +11,7 @@
 #![feature(extern_types)]
 #![feature(nll)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 use back::write::{create_informational_target_machine, create_target_machine};
 
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index 350199f4e98..9bb8db076a8 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -7,6 +7,7 @@
 #![feature(nll)]
 #![feature(associated_type_bounds)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 //! This crate contains codegen code that is used by all codegen backends (LLVM and others).
 //! The backend-agnostic functions of this crate use functions defined in various traits that
diff --git a/compiler/rustc_const_eval/src/lib.rs b/compiler/rustc_const_eval/src/lib.rs
index 92854af55bb..838484876c7 100644
--- a/compiler/rustc_const_eval/src/lib.rs
+++ b/compiler/rustc_const_eval/src/lib.rs
@@ -22,6 +22,7 @@ Rust MIR: a lowered representation of Rust.
 #![feature(trusted_step)]
 #![feature(try_blocks)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate tracing;
diff --git a/compiler/rustc_data_structures/src/lib.rs b/compiler/rustc_data_structures/src/lib.rs
index 181e5180d53..205f1cd77c0 100644
--- a/compiler/rustc_data_structures/src/lib.rs
+++ b/compiler/rustc_data_structures/src/lib.rs
@@ -26,6 +26,7 @@
 #![feature(vec_into_raw_parts)]
 #![allow(rustc::default_hash_types)]
 #![deny(unaligned_references)]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate tracing;
diff --git a/compiler/rustc_driver/src/lib.rs b/compiler/rustc_driver/src/lib.rs
index 2b64312dbef..0f490c33102 100644
--- a/compiler/rustc_driver/src/lib.rs
+++ b/compiler/rustc_driver/src/lib.rs
@@ -8,6 +8,7 @@
 #![feature(nll)]
 #![feature(once_cell)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate tracing;
@@ -845,7 +846,7 @@ Available lint options:
     let builtin = sort_lints(sess, builtin);
 
     let (plugin_groups, builtin_groups): (Vec<_>, _) =
-        lint_store.get_lint_groups().iter().cloned().partition(|&(.., p)| p);
+        lint_store.get_lint_groups().partition(|&(.., p)| p);
     let plugin_groups = sort_lint_groups(plugin_groups);
     let builtin_groups = sort_lint_groups(builtin_groups);
 
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 7582f317b85..a5c954cca13 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -8,6 +8,7 @@
 #![feature(if_let_guard)]
 #![feature(let_else)]
 #![feature(nll)]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_expand/src/lib.rs b/compiler/rustc_expand/src/lib.rs
index dfc07da9169..43a310f4eaf 100644
--- a/compiler/rustc_expand/src/lib.rs
+++ b/compiler/rustc_expand/src/lib.rs
@@ -9,6 +9,7 @@
 #![feature(proc_macro_span)]
 #![feature(try_blocks)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs
index 25601ffb37d..3933746c319 100644
--- a/compiler/rustc_feature/src/builtin_attrs.rs
+++ b/compiler/rustc_feature/src/builtin_attrs.rs
@@ -581,6 +581,9 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     rustc_attr!(
         rustc_trivial_field_reads, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE
     ),
+    // Used by the `rustc::potential_query_instability` lint to warn methods which
+    // might not be stable during incremental compilation.
+    rustc_attr!(rustc_lint_query_instability, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE),
 
     // ==========================================================================
     // Internal attributes, Const related:
diff --git a/compiler/rustc_incremental/src/lib.rs b/compiler/rustc_incremental/src/lib.rs
index df64534ce54..b4df3e1e396 100644
--- a/compiler/rustc_incremental/src/lib.rs
+++ b/compiler/rustc_incremental/src/lib.rs
@@ -5,6 +5,7 @@
 #![feature(let_else)]
 #![feature(nll)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_middle;
diff --git a/compiler/rustc_index/src/bit_set.rs b/compiler/rustc_index/src/bit_set.rs
index 5aa213cb701..cf86c450a5b 100644
--- a/compiler/rustc_index/src/bit_set.rs
+++ b/compiler/rustc_index/src/bit_set.rs
@@ -938,6 +938,12 @@ pub struct GrowableBitSet<T: Idx> {
     bit_set: BitSet<T>,
 }
 
+impl<T: Idx> Default for GrowableBitSet<T> {
+    fn default() -> Self {
+        GrowableBitSet::new_empty()
+    }
+}
+
 impl<T: Idx> GrowableBitSet<T> {
     /// Ensure that the set can hold at least `min_domain_size` elements.
     pub fn ensure(&mut self, min_domain_size: usize) {
diff --git a/compiler/rustc_infer/src/lib.rs b/compiler/rustc_infer/src/lib.rs
index 5f228d1e203..ae79e14db18 100644
--- a/compiler/rustc_infer/src/lib.rs
+++ b/compiler/rustc_infer/src/lib.rs
@@ -23,6 +23,7 @@
 #![feature(min_specialization)]
 #![feature(label_break_value)]
 #![recursion_limit = "512"] // For rustdoc
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_interface/src/lib.rs b/compiler/rustc_interface/src/lib.rs
index b911b108a73..eebeabbd452 100644
--- a/compiler/rustc_interface/src/lib.rs
+++ b/compiler/rustc_interface/src/lib.rs
@@ -6,6 +6,7 @@
 #![feature(nll)]
 #![feature(once_cell)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 mod callbacks;
 pub mod interface;
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 9b24f43f7fd..734b32bb92f 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -2833,7 +2833,7 @@ impl ClashingExternDeclarations {
                 return true;
             }
             let tcx = cx.tcx;
-            if a == b || rustc_middle::ty::TyS::same_type(a, b) {
+            if a == b {
                 // All nominally-same types are structurally same, too.
                 true
             } else {
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index cb08e952586..5da77b9f946 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -143,7 +143,11 @@ impl LintStore {
         &self.lints
     }
 
-    pub fn get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
+    pub fn get_lint_groups<'t>(
+        &'t self,
+    ) -> impl Iterator<Item = (&'static str, Vec<LintId>, bool)> + 't {
+        // This function is not used in a way which observes the order of lints.
+        #[cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
         self.lint_groups
             .iter()
             .filter(|(_, LintGroup { depr, .. })| {
@@ -153,7 +157,6 @@ impl LintStore {
             .map(|(k, LintGroup { lint_ids, from_plugin, .. })| {
                 (*k, lint_ids.clone(), *from_plugin)
             })
-            .collect()
     }
 
     pub fn register_early_pass(
diff --git a/compiler/rustc_lint/src/internal.rs b/compiler/rustc_lint/src/internal.rs
index d8e1162890c..fa8cbeaaf51 100644
--- a/compiler/rustc_lint/src/internal.rs
+++ b/compiler/rustc_lint/src/internal.rs
@@ -5,7 +5,8 @@ use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext}
 use rustc_ast as ast;
 use rustc_errors::Applicability;
 use rustc_hir::def::Res;
-use rustc_hir::{GenericArg, HirId, Item, ItemKind, Node, Path, PathSegment, QPath, Ty, TyKind};
+use rustc_hir::{Expr, ExprKind, GenericArg, Path, PathSegment, QPath};
+use rustc_hir::{HirId, Item, ItemKind, Node, Ty, TyKind};
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
@@ -49,6 +50,63 @@ impl LateLintPass<'_> for DefaultHashTypes {
 }
 
 declare_tool_lint! {
+    pub rustc::POTENTIAL_QUERY_INSTABILITY,
+    Allow,
+    "require explicit opt-in when using potentially unstable methods or functions",
+    report_in_external_macro: true
+}
+
+declare_lint_pass!(QueryStability => [POTENTIAL_QUERY_INSTABILITY]);
+
+impl LateLintPass<'_> for QueryStability {
+    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
+        // FIXME(rustdoc): This lint uses typecheck results, causing rustdoc to
+        // error if there are resolution failures.
+        //
+        // As internal lints are currently always run if there are `unstable_options`,
+        // they are added to the lint store of rustdoc. Internal lints are also
+        // not used via the `lint_mod` query. Crate lints run outside of a query
+        // so rustdoc currently doesn't disable them.
+        //
+        // Instead of relying on this, either change crate lints to a query disabled by
+        // rustdoc, only run internal lints if the user is explicitly opting in
+        // or figure out a different way to avoid running lints for rustdoc.
+        if cx.tcx.sess.opts.actually_rustdoc {
+            return;
+        }
+
+        let (span, def_id, substs) = match expr.kind {
+            ExprKind::MethodCall(segment, _, _)
+                if let Some(def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) =>
+            {
+                (segment.ident.span, def_id, cx.typeck_results().node_substs(expr.hir_id))
+            },
+            _ => {
+                let &ty::FnDef(def_id, substs) =
+                    cx.typeck_results()
+                        .node_type(expr.hir_id)
+                        .kind() else { return };
+                (expr.span, def_id, substs)
+            }
+        };
+        if let Ok(Some(instance)) = ty::Instance::resolve(cx.tcx, cx.param_env, def_id, substs) {
+            let def_id = instance.def_id();
+            if cx.tcx.has_attr(def_id, sym::rustc_lint_query_instability) {
+                cx.struct_span_lint(POTENTIAL_QUERY_INSTABILITY, span, |lint| {
+                    let msg = format!(
+                        "using `{}` can result in unstable query results",
+                        cx.tcx.item_name(def_id)
+                    );
+                    lint.build(&msg)
+                        .note("if you believe this case to be fine, allow this lint and add a comment explaining your rationale")
+                        .emit();
+                })
+            }
+        }
+    }
+}
+
+declare_tool_lint! {
     pub rustc::USAGE_OF_TY_TYKIND,
     Allow,
     "usage of `ty::TyKind` outside of the `ty::sty` module",
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index a87f2b2768d..69863b5ff82 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -30,12 +30,14 @@
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(crate_visibility_modifier)]
+#![feature(if_let_guard)]
 #![feature(iter_order_by)]
 #![feature(let_else)]
 #![feature(never_type)]
 #![feature(nll)]
 #![feature(control_flow_enum)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_middle;
@@ -493,6 +495,8 @@ fn register_internals(store: &mut LintStore) {
     store.register_early_pass(|| Box::new(LintPassImpl));
     store.register_lints(&DefaultHashTypes::get_lints());
     store.register_late_pass(|| Box::new(DefaultHashTypes));
+    store.register_lints(&QueryStability::get_lints());
+    store.register_late_pass(|| Box::new(QueryStability));
     store.register_lints(&ExistingDocKeyword::get_lints());
     store.register_late_pass(|| Box::new(ExistingDocKeyword));
     store.register_lints(&TyTyKind::get_lints());
@@ -505,6 +509,7 @@ fn register_internals(store: &mut LintStore) {
         None,
         vec![
             LintId::of(DEFAULT_HASH_TYPES),
+            LintId::of(POTENTIAL_QUERY_INSTABILITY),
             LintId::of(USAGE_OF_TY_TYKIND),
             LintId::of(PASS_BY_VALUE),
             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 4af68233f0d..f4eba25475e 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -1793,6 +1793,10 @@ declare_lint! {
     Warn,
     "detects name collision with an existing but unstable method",
     @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::Custom(
+            "once this associated item is added to the standard library, \
+             the ambiguity may cause an error or change in behavior!"
+        ),
         reference: "issue #48919 <https://github.com/rust-lang/rust/issues/48919>",
         // Note: this item represents future incompatibility of all unstable functions in the
         //       standard library, and thus should never be removed or changed to an error.
@@ -2335,6 +2339,10 @@ declare_lint! {
     Warn,
     "reservation of a two-phased borrow conflicts with other shared borrows",
     @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::Custom(
+            "this borrowing pattern was not meant to be accepted, \
+            and may become a hard error in the future"
+        ),
         reference: "issue #59159 <https://github.com/rust-lang/rust/issues/59159>",
     };
 }
@@ -3046,6 +3054,7 @@ declare_lint_pass! {
         DEREF_INTO_DYN_SUPERTRAIT,
         DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
         DUPLICATE_MACRO_ATTRIBUTES,
+        SUSPICIOUS_AUTO_TRAIT_IMPLS,
     ]
 }
 
@@ -3622,3 +3631,37 @@ declare_lint! {
     Warn,
     "duplicated attribute"
 }
+
+declare_lint! {
+    /// The `suspicious_auto_trait_impls` lint checks for potentially incorrect
+    /// implementations of auto traits.
+    ///
+    /// ### Example
+    ///
+    /// ```rust
+    /// struct Foo<T>(T);
+    ///
+    /// unsafe impl<T> Send for Foo<*const T> {}
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// A type can implement auto traits, e.g. `Send`, `Sync` and `Unpin`,
+    /// in two different ways: either by writing an explicit impl or if
+    /// all fields of the type implement that auto trait.
+    ///
+    /// The compiler disables the automatic implementation if an explicit one
+    /// exists for given type constructor. The exact rules governing this
+    /// are currently unsound and quite subtle and and will be modified in the future.
+    /// This change will cause the automatic implementation to be disabled in more
+    /// cases, potentially breaking some code.
+    pub SUSPICIOUS_AUTO_TRAIT_IMPLS,
+    Warn,
+    "the rules governing auto traits will change in the future",
+    @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::FutureReleaseSemanticsChange,
+        reference: "issue #93367 <https://github.com/rust-lang/rust/issues/93367>",
+    };
+}
diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
index 3b5d636124d..1f834b7212f 100644
--- a/compiler/rustc_lint_defs/src/lib.rs
+++ b/compiler/rustc_lint_defs/src/lib.rs
@@ -163,12 +163,17 @@ pub enum FutureIncompatibilityReason {
     /// This will be an error in a future release, and
     /// Cargo should create a report even for dependencies
     FutureReleaseErrorReportNow,
+    /// Code that changes meaning in some way in a
+    /// future release.
+    FutureReleaseSemanticsChange,
     /// Previously accepted code that will become an
     /// error in the provided edition
     EditionError(Edition),
     /// Code that changes meaning in some way in
     /// the provided edition
     EditionSemanticsChange(Edition),
+    /// A custom reason.
+    Custom(&'static str),
 }
 
 impl FutureIncompatibilityReason {
diff --git a/compiler/rustc_metadata/src/lib.rs b/compiler/rustc_metadata/src/lib.rs
index 918c3b9daf1..046245080de 100644
--- a/compiler/rustc_metadata/src/lib.rs
+++ b/compiler/rustc_metadata/src/lib.rs
@@ -9,6 +9,7 @@
 #![feature(try_blocks)]
 #![feature(never_type)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 extern crate proc_macro;
 
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index 920eca7a717..e85cb413deb 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -56,6 +56,7 @@
 #![feature(nonzero_ops)]
 #![feature(unwrap_infallible)]
 #![recursion_limit = "512"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate bitflags;
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index c6226c69f30..17c77c1bbd8 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/compiler/rustc_middle/src/lint.rs
@@ -221,7 +221,6 @@ pub fn struct_lint_level<'s, 'd>(
         decorate: Box<dyn for<'b> FnOnce(LintDiagnosticBuilder<'b>) + 'd>,
     ) {
         // Check for future incompatibility lints and issue a stronger warning.
-        let lint_id = LintId::of(lint);
         let future_incompatible = lint.future_incompatible;
 
         let has_future_breakage = future_incompatible.map_or(
@@ -345,31 +344,29 @@ pub fn struct_lint_level<'s, 'd>(
         err.code(DiagnosticId::Lint { name, has_future_breakage, is_force_warn });
 
         if let Some(future_incompatible) = future_incompatible {
-            let explanation = if lint_id == LintId::of(builtin::UNSTABLE_NAME_COLLISIONS) {
-                "once this associated item is added to the standard library, the ambiguity may \
-                 cause an error or change in behavior!"
-                    .to_owned()
-            } else if lint_id == LintId::of(builtin::MUTABLE_BORROW_RESERVATION_CONFLICT) {
-                "this borrowing pattern was not meant to be accepted, and may become a hard error \
-                 in the future"
-                    .to_owned()
-            } else if let FutureIncompatibilityReason::EditionError(edition) =
-                future_incompatible.reason
-            {
-                let current_edition = sess.edition();
-                format!(
-                    "this is accepted in the current edition (Rust {}) but is a hard error in Rust {}!",
-                    current_edition, edition
-                )
-            } else if let FutureIncompatibilityReason::EditionSemanticsChange(edition) =
-                future_incompatible.reason
-            {
-                format!("this changes meaning in Rust {}", edition)
-            } else {
-                "this was previously accepted by the compiler but is being phased out; \
-                 it will become a hard error in a future release!"
-                    .to_owned()
+            let explanation = match future_incompatible.reason {
+                FutureIncompatibilityReason::FutureReleaseError
+                | FutureIncompatibilityReason::FutureReleaseErrorReportNow => {
+                    "this was previously accepted by the compiler but is being phased out; \
+                         it will become a hard error in a future release!"
+                        .to_owned()
+                }
+                FutureIncompatibilityReason::FutureReleaseSemanticsChange => {
+                    "this will change its meaning in a future release!".to_owned()
+                }
+                FutureIncompatibilityReason::EditionError(edition) => {
+                    let current_edition = sess.edition();
+                    format!(
+                        "this is accepted in the current edition (Rust {}) but is a hard error in Rust {}!",
+                        current_edition, edition
+                    )
+                }
+                FutureIncompatibilityReason::EditionSemanticsChange(edition) => {
+                    format!("this changes meaning in Rust {}", edition)
+                }
+                FutureIncompatibilityReason::Custom(reason) => reason.to_owned(),
             };
+
             if future_incompatible.explain_reason {
                 err.warn(&explanation);
             }
diff --git a/compiler/rustc_middle/src/ty/trait_def.rs b/compiler/rustc_middle/src/ty/trait_def.rs
index 9f8053d4a4e..9e32c0162e6 100644
--- a/compiler/rustc_middle/src/ty/trait_def.rs
+++ b/compiler/rustc_middle/src/ty/trait_def.rs
@@ -144,6 +144,23 @@ impl<'tcx> TyCtxt<'tcx> {
         });
     }
 
+    pub fn non_blanket_impls_for_ty(
+        self,
+        def_id: DefId,
+        self_ty: Ty<'tcx>,
+    ) -> impl Iterator<Item = DefId> + 'tcx {
+        let impls = self.trait_impls_of(def_id);
+        if let Some(simp) =
+            fast_reject::simplify_type(self, self_ty, SimplifyParams::No, StripReferences::No)
+        {
+            if let Some(impls) = impls.non_blanket_impls.get(&simp) {
+                return impls.iter().copied();
+            }
+        }
+
+        [].iter().copied()
+    }
+
     /// Applies function to every impl that could possibly match the self type `self_ty` and returns
     /// the first non-none value.
     pub fn find_map_relevant_impl<T, F: FnMut(DefId) -> Option<T>>(
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index 96c27d649e4..3e3473bea0e 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -893,19 +893,6 @@ impl<'tcx> ty::TyS<'tcx> {
         }
     }
 
-    pub fn same_type(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
-        match (&a.kind(), &b.kind()) {
-            (&Adt(did_a, substs_a), &Adt(did_b, substs_b)) => {
-                if did_a != did_b {
-                    return false;
-                }
-
-                substs_a.types().zip(substs_b.types()).all(|(a, b)| Self::same_type(a, b))
-            }
-            _ => a == b,
-        }
-    }
-
     /// Peel off all reference types in this type until there are none left.
     ///
     /// This method is idempotent, i.e. `ty.peel_refs().peel_refs() == ty.peel_refs()`.
diff --git a/compiler/rustc_mir_build/src/lib.rs b/compiler/rustc_mir_build/src/lib.rs
index 38bb00f985a..12ea740d48a 100644
--- a/compiler/rustc_mir_build/src/lib.rs
+++ b/compiler/rustc_mir_build/src/lib.rs
@@ -9,6 +9,7 @@
 #![feature(once_cell)]
 #![feature(min_specialization)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate tracing;
diff --git a/compiler/rustc_mir_transform/src/function_item_references.rs b/compiler/rustc_mir_transform/src/function_item_references.rs
index 1b9fddec2be..2ed14b91778 100644
--- a/compiler/rustc_mir_transform/src/function_item_references.rs
+++ b/compiler/rustc_mir_transform/src/function_item_references.rs
@@ -6,7 +6,7 @@ use rustc_middle::mir::*;
 use rustc_middle::ty::{
     self,
     subst::{GenericArgKind, Subst, SubstsRef},
-    PredicateKind, Ty, TyCtxt, TyS,
+    PredicateKind, Ty, TyCtxt,
 };
 use rustc_session::lint::builtin::FUNCTION_ITEM_REFERENCES;
 use rustc_span::{symbol::sym, Span};
@@ -88,7 +88,7 @@ impl<'tcx> FunctionItemRefChecker<'_, 'tcx> {
                     for generic_inner_ty in arg_def.walk() {
                         if let GenericArgKind::Type(inner_ty) = generic_inner_ty.unpack() {
                             // If the inner type matches the type bound by `Pointer`
-                            if TyS::same_type(inner_ty, bound_ty) {
+                            if inner_ty == bound_ty {
                                 // Do a substitution using the parameters from the callsite
                                 let subst_ty = inner_ty.subst(self.tcx, substs_ref);
                                 if let Some((fn_id, fn_substs)) =
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
index 8e1601fb719..129efc2b523 100644
--- a/compiler/rustc_mir_transform/src/lib.rs
+++ b/compiler/rustc_mir_transform/src/lib.rs
@@ -10,6 +10,7 @@
 #![feature(trusted_step)]
 #![feature(try_blocks)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate tracing;
diff --git a/compiler/rustc_monomorphize/src/lib.rs b/compiler/rustc_monomorphize/src/lib.rs
index 21ac174ba90..bbc65b09ece 100644
--- a/compiler/rustc_monomorphize/src/lib.rs
+++ b/compiler/rustc_monomorphize/src/lib.rs
@@ -4,6 +4,7 @@
 #![feature(control_flow_enum)]
 #![feature(let_else)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate tracing;
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index ec4cefa3537..ca511f7b814 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -62,7 +62,7 @@ impl CheckAttrVisitor<'_> {
     fn check_attributes(
         &self,
         hir_id: HirId,
-        span: &Span,
+        span: Span,
         target: Target,
         item: Option<ItemLike<'_>>,
     ) {
@@ -81,7 +81,7 @@ impl CheckAttrVisitor<'_> {
                 }
                 sym::target_feature => self.check_target_feature(hir_id, attr, span, target),
                 sym::track_caller => {
-                    self.check_track_caller(hir_id, &attr.span, attrs, span, target)
+                    self.check_track_caller(hir_id, attr.span, attrs, span, target)
                 }
                 sym::doc => self.check_doc_attrs(
                     attr,
@@ -106,6 +106,9 @@ impl CheckAttrVisitor<'_> {
                 sym::rustc_legacy_const_generics => {
                     self.check_rustc_legacy_const_generics(&attr, span, target, item)
                 }
+                sym::rustc_lint_query_instability => {
+                    self.check_rustc_lint_query_instability(&attr, span, target)
+                }
                 sym::rustc_clean
                 | sym::rustc_dirty
                 | sym::rustc_if_this_changed
@@ -253,7 +256,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Checks if an `#[inline]` is applied to a function or a closure. Returns `true` if valid.
-    fn check_inline(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) -> bool {
+    fn check_inline(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
         match target {
             Target::Fn
             | Target::Closure
@@ -296,7 +299,7 @@ impl CheckAttrVisitor<'_> {
                     E0518,
                     "attribute should be applied to function or closure",
                 )
-                .span_label(*span, "not a function or closure")
+                .span_label(span, "not a function or closure")
                 .emit();
                 false
             }
@@ -335,7 +338,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Checks if `#[naked]` is applied to a function definition.
-    fn check_naked(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) -> bool {
+    fn check_naked(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
         match target {
             Target::Fn
             | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
@@ -354,7 +357,7 @@ impl CheckAttrVisitor<'_> {
                         attr.span,
                         "attribute should be applied to a function definition",
                     )
-                    .span_label(*span, "not a function definition")
+                    .span_label(span, "not a function definition")
                     .emit();
                 false
             }
@@ -362,7 +365,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Checks if `#[cmse_nonsecure_entry]` is applied to a function definition.
-    fn check_cmse_nonsecure_entry(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
+    fn check_cmse_nonsecure_entry(&self, attr: &Attribute, span: Span, target: Target) -> bool {
         match target {
             Target::Fn
             | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
@@ -373,7 +376,7 @@ impl CheckAttrVisitor<'_> {
                         attr.span,
                         "attribute should be applied to a function definition",
                     )
-                    .span_label(*span, "not a function definition")
+                    .span_label(span, "not a function definition")
                     .emit();
                 false
             }
@@ -384,16 +387,16 @@ impl CheckAttrVisitor<'_> {
     fn check_track_caller(
         &self,
         hir_id: HirId,
-        attr_span: &Span,
+        attr_span: Span,
         attrs: &[Attribute],
-        span: &Span,
+        span: Span,
         target: Target,
     ) -> bool {
         match target {
             _ if attrs.iter().any(|attr| attr.has_name(sym::naked)) => {
                 struct_span_err!(
                     self.tcx.sess,
-                    *attr_span,
+                    attr_span,
                     E0736,
                     "cannot use `#[track_caller]` with `#[naked]`",
                 )
@@ -414,11 +417,11 @@ impl CheckAttrVisitor<'_> {
             _ => {
                 struct_span_err!(
                     self.tcx.sess,
-                    *attr_span,
+                    attr_span,
                     E0739,
                     "attribute should be applied to function"
                 )
-                .span_label(*span, "not a function")
+                .span_label(span, "not a function")
                 .emit();
                 false
             }
@@ -430,7 +433,7 @@ impl CheckAttrVisitor<'_> {
         &self,
         hir_id: HirId,
         attr: &Attribute,
-        span: &Span,
+        span: Span,
         target: Target,
     ) -> bool {
         match target {
@@ -450,7 +453,7 @@ impl CheckAttrVisitor<'_> {
                     E0701,
                     "attribute can only be applied to a struct or enum"
                 )
-                .span_label(*span, "not a struct or enum")
+                .span_label(span, "not a struct or enum")
                 .emit();
                 false
             }
@@ -458,7 +461,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Checks if the `#[marker]` attribute on an `item` is valid. Returns `true` if valid.
-    fn check_marker(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) -> bool {
+    fn check_marker(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
         match target {
             Target::Trait => true,
             // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
@@ -473,7 +476,7 @@ impl CheckAttrVisitor<'_> {
                 self.tcx
                     .sess
                     .struct_span_err(attr.span, "attribute can only be applied to a trait")
-                    .span_label(*span, "not a trait")
+                    .span_label(span, "not a trait")
                     .emit();
                 false
             }
@@ -484,7 +487,7 @@ impl CheckAttrVisitor<'_> {
     fn check_rustc_must_implement_one_of(
         &self,
         attr: &Attribute,
-        span: &Span,
+        span: Span,
         target: Target,
     ) -> bool {
         match target {
@@ -493,7 +496,7 @@ impl CheckAttrVisitor<'_> {
                 self.tcx
                     .sess
                     .struct_span_err(attr.span, "attribute can only be applied to a trait")
-                    .span_label(*span, "not a trait")
+                    .span_label(span, "not a trait")
                     .emit();
                 false
             }
@@ -505,7 +508,7 @@ impl CheckAttrVisitor<'_> {
         &self,
         hir_id: HirId,
         attr: &Attribute,
-        span: &Span,
+        span: Span,
         target: Target,
     ) -> bool {
         match target {
@@ -521,7 +524,7 @@ impl CheckAttrVisitor<'_> {
                              being phased out; it will become a hard error in \
                              a future release!",
                         )
-                        .span_label(*span, "not a function")
+                        .span_label(span, "not a function")
                         .emit();
                 });
                 true
@@ -538,7 +541,7 @@ impl CheckAttrVisitor<'_> {
                 self.tcx
                     .sess
                     .struct_span_err(attr.span, "attribute should be applied to a function")
-                    .span_label(*span, "not a function")
+                    .span_label(span, "not a function")
                     .emit();
                 false
             }
@@ -1090,7 +1093,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Warns against some misuses of `#[pass_by_value]`
-    fn check_pass_by_value(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
+    fn check_pass_by_value(&self, attr: &Attribute, span: Span, target: Target) -> bool {
         match target {
             Target::Struct | Target::Enum | Target::TyAlias => true,
             _ => {
@@ -1100,7 +1103,7 @@ impl CheckAttrVisitor<'_> {
                         attr.span,
                         "`pass_by_value` attribute should be applied to a struct, enum or type alias.",
                     )
-                    .span_label(*span, "is not a struct, enum or type alias")
+                    .span_label(span, "is not a struct, enum or type alias")
                     .emit();
                 false
             }
@@ -1108,13 +1111,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Warns against some misuses of `#[must_use]`
-    fn check_must_use(
-        &self,
-        hir_id: HirId,
-        attr: &Attribute,
-        span: &Span,
-        _target: Target,
-    ) -> bool {
+    fn check_must_use(&self, hir_id: HirId, attr: &Attribute, span: Span, _target: Target) -> bool {
         let node = self.tcx.hir().get(hir_id);
         if let Some(fn_node) = node.fn_kind() {
             if let rustc_hir::IsAsync::Async = fn_node.asyncness() {
@@ -1125,7 +1122,7 @@ impl CheckAttrVisitor<'_> {
                               function, not the value within",
                     )
                     .span_label(
-                        *span,
+                        span,
                         "this attribute does nothing, the `Future`s \
                                 returned by async functions are already `must_use`",
                     )
@@ -1139,14 +1136,14 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Checks if `#[must_not_suspend]` is applied to a function. Returns `true` if valid.
-    fn check_must_not_suspend(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
+    fn check_must_not_suspend(&self, attr: &Attribute, span: Span, target: Target) -> bool {
         match target {
             Target::Struct | Target::Enum | Target::Union | Target::Trait => true,
             _ => {
                 self.tcx
                     .sess
                     .struct_span_err(attr.span, "`must_not_suspend` attribute should be applied to a struct, enum, or trait")
-                        .span_label(*span, "is not a struct, enum, or trait")
+                        .span_label(span, "is not a struct, enum, or trait")
                         .emit();
                 false
             }
@@ -1154,7 +1151,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Checks if `#[cold]` is applied to a non-function. Returns `true` if valid.
-    fn check_cold(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) {
+    fn check_cold(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
         match target {
             Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => {}
             // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
@@ -1174,7 +1171,7 @@ impl CheckAttrVisitor<'_> {
                              being phased out; it will become a hard error in \
                              a future release!",
                         )
-                        .span_label(*span, "not a function")
+                        .span_label(span, "not a function")
                         .emit();
                 });
             }
@@ -1182,7 +1179,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Checks if `#[link]` is applied to an item other than a foreign module.
-    fn check_link(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) {
+    fn check_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
         match target {
             Target::ForeignMod => {}
             _ => {
@@ -1194,7 +1191,7 @@ impl CheckAttrVisitor<'_> {
                          a future release!",
                     );
 
-                    diag.span_label(*span, "not an `extern` block");
+                    diag.span_label(span, "not an `extern` block");
                     diag.emit();
                 });
             }
@@ -1202,7 +1199,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Checks if `#[link_name]` is applied to an item other than a foreign function or static.
-    fn check_link_name(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) {
+    fn check_link_name(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
         match target {
             Target::ForeignFn | Target::ForeignStatic => {}
             // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
@@ -1236,7 +1233,7 @@ impl CheckAttrVisitor<'_> {
                         }
                     }
 
-                    diag.span_label(*span, "not a foreign function or static");
+                    diag.span_label(span, "not a foreign function or static");
                     diag.emit();
                 });
             }
@@ -1244,7 +1241,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Checks if `#[no_link]` is applied to an `extern crate`. Returns `true` if valid.
-    fn check_no_link(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) -> bool {
+    fn check_no_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
         match target {
             Target::ExternCrate => true,
             // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
@@ -1262,7 +1259,7 @@ impl CheckAttrVisitor<'_> {
                         attr.span,
                         "attribute should be applied to an `extern crate` item",
                     )
-                    .span_label(*span, "not an `extern crate` item")
+                    .span_label(span, "not an `extern crate` item")
                     .emit();
                 false
             }
@@ -1278,7 +1275,7 @@ impl CheckAttrVisitor<'_> {
         &self,
         hir_id: HirId,
         attr: &Attribute,
-        span: &Span,
+        span: Span,
         target: Target,
     ) -> bool {
         match target {
@@ -1299,7 +1296,7 @@ impl CheckAttrVisitor<'_> {
                         attr.span,
                         "attribute should be applied to a free function, impl method or static",
                     )
-                    .span_label(*span, "not a free function, impl method or static")
+                    .span_label(span, "not a free function, impl method or static")
                     .emit();
                 false
             }
@@ -1309,14 +1306,14 @@ impl CheckAttrVisitor<'_> {
     fn check_rustc_layout_scalar_valid_range(
         &self,
         attr: &Attribute,
-        span: &Span,
+        span: Span,
         target: Target,
     ) -> bool {
         if target != Target::Struct {
             self.tcx
                 .sess
                 .struct_span_err(attr.span, "attribute should be applied to a struct")
-                .span_label(*span, "not a struct")
+                .span_label(span, "not a struct")
                 .emit();
             return false;
         }
@@ -1341,7 +1338,7 @@ impl CheckAttrVisitor<'_> {
     fn check_rustc_legacy_const_generics(
         &self,
         attr: &Attribute,
-        span: &Span,
+        span: Span,
         target: Target,
         item: Option<ItemLike<'_>>,
     ) -> bool {
@@ -1350,7 +1347,7 @@ impl CheckAttrVisitor<'_> {
             self.tcx
                 .sess
                 .struct_span_err(attr.span, "attribute should be applied to a function")
-                .span_label(*span, "not a function")
+                .span_label(span, "not a function")
                 .emit();
             return false;
         }
@@ -1436,6 +1433,25 @@ impl CheckAttrVisitor<'_> {
         }
     }
 
+    fn check_rustc_lint_query_instability(
+        &self,
+        attr: &Attribute,
+        span: Span,
+        target: Target,
+    ) -> bool {
+        let is_function = matches!(target, Target::Fn | Target::Method(..));
+        if !is_function {
+            self.tcx
+                .sess
+                .struct_span_err(attr.span, "attribute should be applied to a function")
+                .span_label(span, "not a function")
+                .emit();
+            false
+        } else {
+            true
+        }
+    }
+
     /// Checks that the dep-graph debugging attributes are only present when the query-dep-graph
     /// option is passed to the compiler.
     fn check_rustc_dirty_clean(&self, attr: &Attribute) -> bool {
@@ -1451,7 +1467,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Checks if `#[link_section]` is applied to a function or static.
-    fn check_link_section(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) {
+    fn check_link_section(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
         match target {
             Target::Static | Target::Fn | Target::Method(..) => {}
             // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
@@ -1471,7 +1487,7 @@ impl CheckAttrVisitor<'_> {
                              being phased out; it will become a hard error in \
                              a future release!",
                         )
-                        .span_label(*span, "not a function or static")
+                        .span_label(span, "not a function or static")
                         .emit();
                 });
             }
@@ -1479,7 +1495,7 @@ impl CheckAttrVisitor<'_> {
     }
 
     /// Checks if `#[no_mangle]` is applied to a function or static.
-    fn check_no_mangle(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) {
+    fn check_no_mangle(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
         match target {
             Target::Static | Target::Fn => {}
             Target::Method(..) if self.is_impl_item(hir_id) => {}
@@ -1509,7 +1525,7 @@ impl CheckAttrVisitor<'_> {
                             being phased out; it will become a hard error in \
                             a future release!",
                     )
-                    .span_label(*span, format!("foreign {}", foreign_item_kind))
+                    .span_label(span, format!("foreign {}", foreign_item_kind))
                     .note("symbol names in extern blocks are not mangled")
                     .span_suggestion(
                         attr.span,
@@ -1532,7 +1548,7 @@ impl CheckAttrVisitor<'_> {
                          being phased out; it will become a hard error in \
                          a future release!",
                     )
-                    .span_label(*span, "not a free function, impl method or static")
+                    .span_label(span, "not a free function, impl method or static")
                     .emit();
                 });
             }
@@ -1543,7 +1559,7 @@ impl CheckAttrVisitor<'_> {
     fn check_repr(
         &self,
         attrs: &[Attribute],
-        span: &Span,
+        span: Span,
         target: Target,
         item: Option<ItemLike<'_>>,
         hir_id: HirId,
@@ -1677,7 +1693,7 @@ impl CheckAttrVisitor<'_> {
                 "{}",
                 &format!("attribute should be applied to {} {}", article, allowed_targets)
             )
-            .span_label(*span, &format!("not {} {}", article, allowed_targets))
+            .span_label(span, &format!("not {} {}", article, allowed_targets))
             .emit();
         }
 
@@ -1740,7 +1756,7 @@ impl CheckAttrVisitor<'_> {
         &self,
         hir_id: HirId,
         attr: &Attribute,
-        span: &Span,
+        span: Span,
         target: Target,
         attrs: &[Attribute],
     ) -> bool {
@@ -1773,7 +1789,7 @@ impl CheckAttrVisitor<'_> {
                 self.tcx
                     .sess
                     .struct_span_err(attr.span, "attribute should be applied to a macro")
-                    .span_label(*span, "not a macro")
+                    .span_label(span, "not a macro")
                     .emit();
                 false
             }
@@ -1786,7 +1802,7 @@ impl CheckAttrVisitor<'_> {
         &self,
         hir_id: HirId,
         attr: &Attribute,
-        span: &Span,
+        span: Span,
         target: Target,
     ) -> bool {
         match target {
@@ -1807,7 +1823,7 @@ impl CheckAttrVisitor<'_> {
                 self.tcx
                     .sess
                     .struct_span_err(attr.span, "attribute should be applied to `const fn`")
-                    .span_label(*span, "not a `const fn`")
+                    .span_label(span, "not a `const fn`")
                     .emit();
                 false
             }
@@ -1818,7 +1834,7 @@ impl CheckAttrVisitor<'_> {
     fn check_default_method_body_is_const(
         &self,
         attr: &Attribute,
-        span: &Span,
+        span: Span,
         target: Target,
     ) -> bool {
         match target {
@@ -1830,14 +1846,14 @@ impl CheckAttrVisitor<'_> {
                         attr.span,
                         "attribute should be applied to a trait method with body",
                     )
-                    .span_label(*span, "not a trait method or missing a body")
+                    .span_label(span, "not a trait method or missing a body")
                     .emit();
                 false
             }
         }
     }
 
-    fn check_stability_promotable(&self, attr: &Attribute, _span: &Span, target: Target) -> bool {
+    fn check_stability_promotable(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
         match target {
             Target::Expression => {
                 self.tcx
@@ -1850,7 +1866,7 @@ impl CheckAttrVisitor<'_> {
         }
     }
 
-    fn check_deprecated(&self, hir_id: HirId, attr: &Attribute, _span: &Span, target: Target) {
+    fn check_deprecated(&self, hir_id: HirId, attr: &Attribute, _span: Span, target: Target) {
         match target {
             Target::Closure | Target::Expression | Target::Statement | Target::Arm => {
                 self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
@@ -1912,29 +1928,29 @@ impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
         }
 
         let target = Target::from_item(item);
-        self.check_attributes(item.hir_id(), &item.span, target, Some(ItemLike::Item(item)));
+        self.check_attributes(item.hir_id(), item.span, target, Some(ItemLike::Item(item)));
         intravisit::walk_item(self, item)
     }
 
     fn visit_generic_param(&mut self, generic_param: &'tcx hir::GenericParam<'tcx>) {
         let target = Target::from_generic_param(generic_param);
-        self.check_attributes(generic_param.hir_id, &generic_param.span, target, None);
+        self.check_attributes(generic_param.hir_id, generic_param.span, target, None);
         intravisit::walk_generic_param(self, generic_param)
     }
 
     fn visit_trait_item(&mut self, trait_item: &'tcx TraitItem<'tcx>) {
         let target = Target::from_trait_item(trait_item);
-        self.check_attributes(trait_item.hir_id(), &trait_item.span, target, None);
+        self.check_attributes(trait_item.hir_id(), trait_item.span, target, None);
         intravisit::walk_trait_item(self, trait_item)
     }
 
     fn visit_field_def(&mut self, struct_field: &'tcx hir::FieldDef<'tcx>) {
-        self.check_attributes(struct_field.hir_id, &struct_field.span, Target::Field, None);
+        self.check_attributes(struct_field.hir_id, struct_field.span, Target::Field, None);
         intravisit::walk_field_def(self, struct_field);
     }
 
     fn visit_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) {
-        self.check_attributes(arm.hir_id, &arm.span, Target::Arm, None);
+        self.check_attributes(arm.hir_id, arm.span, Target::Arm, None);
         intravisit::walk_arm(self, arm);
     }
 
@@ -1942,7 +1958,7 @@ impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
         let target = Target::from_foreign_item(f_item);
         self.check_attributes(
             f_item.hir_id(),
-            &f_item.span,
+            f_item.span,
             target,
             Some(ItemLike::ForeignItem(f_item)),
         );
@@ -1951,14 +1967,14 @@ impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
 
     fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
         let target = target_from_impl_item(self.tcx, impl_item);
-        self.check_attributes(impl_item.hir_id(), &impl_item.span, target, None);
+        self.check_attributes(impl_item.hir_id(), impl_item.span, target, None);
         intravisit::walk_impl_item(self, impl_item)
     }
 
     fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
         // When checking statements ignore expressions, they will be checked later.
         if let hir::StmtKind::Local(ref l) = stmt.kind {
-            self.check_attributes(l.hir_id, &stmt.span, Target::Statement, None);
+            self.check_attributes(l.hir_id, stmt.span, Target::Statement, None);
         }
         intravisit::walk_stmt(self, stmt)
     }
@@ -1969,7 +1985,7 @@ impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
             _ => Target::Expression,
         };
 
-        self.check_attributes(expr.hir_id, &expr.span, target, None);
+        self.check_attributes(expr.hir_id, expr.span, target, None);
         intravisit::walk_expr(self, expr)
     }
 
@@ -1979,12 +1995,12 @@ impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
         generics: &'tcx hir::Generics<'tcx>,
         item_id: HirId,
     ) {
-        self.check_attributes(variant.id, &variant.span, Target::Variant, None);
+        self.check_attributes(variant.id, variant.span, Target::Variant, None);
         intravisit::walk_variant(self, variant, generics, item_id)
     }
 
     fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
-        self.check_attributes(param.hir_id, &param.span, Target::Param, None);
+        self.check_attributes(param.hir_id, param.span, Target::Param, None);
 
         intravisit::walk_param(self, param);
     }
@@ -2076,7 +2092,7 @@ fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
     let check_attr_visitor = &mut CheckAttrVisitor { tcx };
     tcx.hir().visit_item_likes_in_module(module_def_id, &mut check_attr_visitor.as_deep_visitor());
     if module_def_id.is_top_level_module() {
-        check_attr_visitor.check_attributes(CRATE_HIR_ID, &DUMMY_SP, Target::Mod, None);
+        check_attr_visitor.check_attributes(CRATE_HIR_ID, DUMMY_SP, Target::Mod, None);
         check_invalid_crate_level_attr(tcx, tcx.hir().krate_attrs());
     }
 }
diff --git a/compiler/rustc_passes/src/lib.rs b/compiler/rustc_passes/src/lib.rs
index 2075fee7171..89404804098 100644
--- a/compiler/rustc_passes/src/lib.rs
+++ b/compiler/rustc_passes/src/lib.rs
@@ -13,6 +13,7 @@
 #![feature(nll)]
 #![feature(try_blocks)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_middle;
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
index d59c12fc2fa..7c511ccbd57 100644
--- a/compiler/rustc_privacy/src/lib.rs
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -4,6 +4,7 @@
 #![feature(try_blocks)]
 #![feature(associated_type_defaults)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 use rustc_ast::MacroDef;
 use rustc_attr as attr;
diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
index de9d4253537..bf859decc70 100644
--- a/compiler/rustc_query_impl/src/lib.rs
+++ b/compiler/rustc_query_impl/src/lib.rs
@@ -7,6 +7,7 @@
 #![feature(once_cell)]
 #![feature(rustc_attrs)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_query_system/src/lib.rs b/compiler/rustc_query_system/src/lib.rs
index 0436e07e2d4..750ac76a771 100644
--- a/compiler/rustc_query_system/src/lib.rs
+++ b/compiler/rustc_query_system/src/lib.rs
@@ -5,6 +5,7 @@
 #![feature(let_else)]
 #![feature(min_specialization)]
 #![feature(extern_types)]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate tracing;
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 45cc64ea194..d5ad95ace97 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -18,6 +18,7 @@
 #![feature(nll)]
 #![recursion_limit = "256"]
 #![allow(rustdoc::private_intra_doc_links)]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate tracing;
diff --git a/compiler/rustc_save_analysis/src/lib.rs b/compiler/rustc_save_analysis/src/lib.rs
index 570fa873a23..c14b459570f 100644
--- a/compiler/rustc_save_analysis/src/lib.rs
+++ b/compiler/rustc_save_analysis/src/lib.rs
@@ -2,6 +2,7 @@
 #![feature(if_let_guard)]
 #![feature(nll)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 mod dump_visitor;
 mod dumper;
diff --git a/compiler/rustc_session/src/lib.rs b/compiler/rustc_session/src/lib.rs
index 399b616915e..383250cd68f 100644
--- a/compiler/rustc_session/src/lib.rs
+++ b/compiler/rustc_session/src/lib.rs
@@ -3,6 +3,7 @@
 #![feature(min_specialization)]
 #![feature(once_cell)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index 2c3db35bb66..823a927fd8c 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -21,6 +21,7 @@
 #![feature(negative_impls)]
 #![feature(nll)]
 #![feature(min_specialization)]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 198391cbe9c..18627cd2c09 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1171,6 +1171,7 @@ symbols! {
         rustc_layout_scalar_valid_range_end,
         rustc_layout_scalar_valid_range_start,
         rustc_legacy_const_generics,
+        rustc_lint_query_instability,
         rustc_macro_transparency,
         rustc_main,
         rustc_mir,
diff --git a/compiler/rustc_symbol_mangling/src/lib.rs b/compiler/rustc_symbol_mangling/src/lib.rs
index c5e85b14421..f4d1f41902a 100644
--- a/compiler/rustc_symbol_mangling/src/lib.rs
+++ b/compiler/rustc_symbol_mangling/src/lib.rs
@@ -91,6 +91,7 @@
 #![feature(never_type)]
 #![feature(nll)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_middle;
diff --git a/compiler/rustc_target/src/abi/call/s390x.rs b/compiler/rustc_target/src/abi/call/s390x.rs
index 38aaee64a4d..13706e8c217 100644
--- a/compiler/rustc_target/src/abi/call/s390x.rs
+++ b/compiler/rustc_target/src/abi/call/s390x.rs
@@ -2,7 +2,7 @@
 // for a pre-z13 machine or using -mno-vx.
 
 use crate::abi::call::{ArgAbi, FnAbi, Reg};
-use crate::abi::{self, HasDataLayout, TyAbiInterface, TyAndLayout};
+use crate::abi::{HasDataLayout, TyAbiInterface};
 
 fn classify_ret<Ty>(ret: &mut ArgAbi<'_, Ty>) {
     if !ret.layout.is_aggregate() && ret.layout.size.bits() <= 64 {
@@ -12,24 +12,6 @@ fn classify_ret<Ty>(ret: &mut ArgAbi<'_, Ty>) {
     }
 }
 
-fn is_single_fp_element<'a, Ty, C>(cx: &C, layout: TyAndLayout<'a, Ty>) -> bool
-where
-    Ty: TyAbiInterface<'a, C>,
-    C: HasDataLayout,
-{
-    match layout.abi {
-        abi::Abi::Scalar(scalar) => scalar.value.is_float(),
-        abi::Abi::Aggregate { .. } => {
-            if layout.fields.count() == 1 && layout.fields.offset(0).bytes() == 0 {
-                is_single_fp_element(cx, layout.field(cx, 0))
-            } else {
-                false
-            }
-        }
-        _ => false,
-    }
-}
-
 fn classify_arg<'a, Ty, C>(cx: &C, arg: &mut ArgAbi<'a, Ty>)
 where
     Ty: TyAbiInterface<'a, C> + Copy,
@@ -40,7 +22,7 @@ where
         return;
     }
 
-    if is_single_fp_element(cx, arg.layout) {
+    if arg.layout.is_single_fp_element(cx) {
         match arg.layout.size.bytes() {
             4 => arg.cast_to(Reg::f32()),
             8 => arg.cast_to(Reg::f64()),
diff --git a/compiler/rustc_target/src/abi/call/x86.rs b/compiler/rustc_target/src/abi/call/x86.rs
index 28064d85bf1..d169087dfbd 100644
--- a/compiler/rustc_target/src/abi/call/x86.rs
+++ b/compiler/rustc_target/src/abi/call/x86.rs
@@ -1,5 +1,5 @@
 use crate::abi::call::{ArgAttribute, FnAbi, PassMode, Reg, RegKind};
-use crate::abi::{self, HasDataLayout, TyAbiInterface, TyAndLayout};
+use crate::abi::{HasDataLayout, TyAbiInterface};
 use crate::spec::HasTargetSpec;
 
 #[derive(PartialEq)]
@@ -8,24 +8,6 @@ pub enum Flavor {
     Fastcall,
 }
 
-fn is_single_fp_element<'a, Ty, C>(cx: &C, layout: TyAndLayout<'a, Ty>) -> bool
-where
-    Ty: TyAbiInterface<'a, C> + Copy,
-    C: HasDataLayout,
-{
-    match layout.abi {
-        abi::Abi::Scalar(scalar) => scalar.value.is_float(),
-        abi::Abi::Aggregate { .. } => {
-            if layout.fields.count() == 1 && layout.fields.offset(0).bytes() == 0 {
-                is_single_fp_element(cx, layout.field(cx, 0))
-            } else {
-                false
-            }
-        }
-        _ => false,
-    }
-}
-
 pub fn compute_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>, flavor: Flavor)
 where
     Ty: TyAbiInterface<'a, C> + Copy,
@@ -44,7 +26,7 @@ where
             if t.abi_return_struct_as_int {
                 // According to Clang, everyone but MSVC returns single-element
                 // float aggregates directly in a floating-point register.
-                if !t.is_like_msvc && is_single_fp_element(cx, fn_abi.ret.layout) {
+                if !t.is_like_msvc && fn_abi.ret.layout.is_single_fp_element(cx) {
                     match fn_abi.ret.layout.size.bytes() {
                         4 => fn_abi.ret.cast_to(Reg::f32()),
                         8 => fn_abi.ret.cast_to(Reg::f64()),
diff --git a/compiler/rustc_target/src/abi/mod.rs b/compiler/rustc_target/src/abi/mod.rs
index a57ad8f2bbd..7f1fd28b30d 100644
--- a/compiler/rustc_target/src/abi/mod.rs
+++ b/compiler/rustc_target/src/abi/mod.rs
@@ -1276,6 +1276,24 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
     {
         Ty::ty_and_layout_pointee_info_at(self, cx, offset)
     }
+
+    pub fn is_single_fp_element<C>(self, cx: &C) -> bool
+    where
+        Ty: TyAbiInterface<'a, C>,
+        C: HasDataLayout,
+    {
+        match self.abi {
+            Abi::Scalar(scalar) => scalar.value.is_float(),
+            Abi::Aggregate { .. } => {
+                if self.fields.count() == 1 && self.fields.offset(0).bytes() == 0 {
+                    self.field(cx, 0).is_single_fp_element(cx)
+                } else {
+                    false
+                }
+            }
+            _ => false,
+        }
+    }
 }
 
 impl<'a, Ty> TyAndLayout<'a, Ty> {
diff --git a/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnu.rs
index c2484f2d8f6..aefbb398286 100644
--- a/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/x86_64_unknown_linux_gnu.rs
@@ -7,6 +7,7 @@ pub fn target() -> Target {
     base.pre_link_args.entry(LinkerFlavor::Gcc).or_default().push("-m64".to_string());
     // don't use probe-stack=inline-asm until rust#83139 and rust#84667 are resolved
     base.stack_probes = StackProbeType::Call;
+    base.static_position_independent_executables = true;
     base.supported_sanitizers = SanitizerSet::ADDRESS
         | SanitizerSet::CFI
         | SanitizerSet::LEAK
diff --git a/compiler/rustc_trait_selection/src/lib.rs b/compiler/rustc_trait_selection/src/lib.rs
index 17e7b481890..0041f596405 100644
--- a/compiler/rustc_trait_selection/src/lib.rs
+++ b/compiler/rustc_trait_selection/src/lib.rs
@@ -22,6 +22,7 @@
 #![feature(crate_visibility_modifier)]
 #![feature(control_flow_enum)]
 #![recursion_limit = "512"] // For rustdoc
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 8c0dbe9b064..8cde93ed9d8 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -1555,7 +1555,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             // `erase_late_bound_regions`.
             let ty_erased = self.tcx.erase_late_bound_regions(ty);
             let ty_erased = self.tcx.erase_regions(ty_erased);
-            let eq = ty::TyS::same_type(ty_erased, target_ty_erased);
+            let eq = ty_erased == target_ty_erased;
             debug!(
                 "maybe_note_obligation_cause_for_async_await: ty_erased={:?} \
                     target_ty_erased={:?} eq={:?}",
diff --git a/compiler/rustc_ty_utils/src/representability.rs b/compiler/rustc_ty_utils/src/representability.rs
index fb7fdacf5e6..1717959acc1 100644
--- a/compiler/rustc_ty_utils/src/representability.rs
+++ b/compiler/rustc_ty_utils/src/representability.rs
@@ -322,7 +322,7 @@ fn is_type_structurally_recursive_inner<'tcx>(
                 // struct Foo { Option<Option<Foo>> }
 
                 for &seen_adt in iter {
-                    if ty::TyS::same_type(ty, seen_adt) {
+                    if ty == seen_adt {
                         debug!("ContainsRecursive: {:?} contains {:?}", seen_adt, ty);
                         return Representability::ContainsRecursive;
                     }
diff --git a/compiler/rustc_typeck/src/coherence/orphan.rs b/compiler/rustc_typeck/src/coherence/orphan.rs
index e954b4cf512..777bd640669 100644
--- a/compiler/rustc_typeck/src/coherence/orphan.rs
+++ b/compiler/rustc_typeck/src/coherence/orphan.rs
@@ -1,24 +1,33 @@
 //! Orphan checker: every impl either implements a trait defined in this
 //! crate or pertains to a type defined in this crate.
 
+use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::struct_span_err;
 use rustc_errors::ErrorReported;
 use rustc_hir as hir;
+use rustc_index::bit_set::GrowableBitSet;
 use rustc_infer::infer::TyCtxtInferExt;
-use rustc_middle::ty::{self, TyCtxt};
-use rustc_span::def_id::LocalDefId;
+use rustc_middle::ty::subst::{GenericArg, InternalSubsts};
+use rustc_middle::ty::{self, ImplPolarity, Ty, TyCtxt, TypeFoldable, TypeVisitor};
+use rustc_session::lint;
+use rustc_span::def_id::{DefId, LocalDefId};
 use rustc_span::Span;
 use rustc_trait_selection::traits;
+use std::ops::ControlFlow;
 
 pub(super) fn orphan_check_crate(tcx: TyCtxt<'_>, (): ()) -> &[LocalDefId] {
     let mut errors = Vec::new();
-    for (_trait, impls_of_trait) in tcx.all_local_trait_impls(()) {
+    for (&trait_def_id, impls_of_trait) in tcx.all_local_trait_impls(()) {
         for &impl_of_trait in impls_of_trait {
             match orphan_check_impl(tcx, impl_of_trait) {
                 Ok(()) => {}
                 Err(ErrorReported) => errors.push(impl_of_trait),
             }
         }
+
+        if tcx.trait_is_auto(trait_def_id) {
+            lint_auto_trait_impls(tcx, trait_def_id, impls_of_trait);
+        }
     }
     tcx.arena.alloc_slice(&errors)
 }
@@ -265,3 +274,201 @@ fn emit_orphan_check_error<'tcx>(
 
     Err(ErrorReported)
 }
+
+#[derive(Default)]
+struct AreUniqueParamsVisitor {
+    seen: GrowableBitSet<u32>,
+}
+
+#[derive(Copy, Clone)]
+enum NotUniqueParam<'tcx> {
+    DuplicateParam(GenericArg<'tcx>),
+    NotParam(GenericArg<'tcx>),
+}
+
+impl<'tcx> TypeVisitor<'tcx> for AreUniqueParamsVisitor {
+    type BreakTy = NotUniqueParam<'tcx>;
+    fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+        match t.kind() {
+            ty::Param(p) => {
+                if self.seen.insert(p.index) {
+                    ControlFlow::CONTINUE
+                } else {
+                    ControlFlow::Break(NotUniqueParam::DuplicateParam(t.into()))
+                }
+            }
+            _ => ControlFlow::Break(NotUniqueParam::NotParam(t.into())),
+        }
+    }
+    fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
+        match r {
+            ty::ReEarlyBound(p) => {
+                if self.seen.insert(p.index) {
+                    ControlFlow::CONTINUE
+                } else {
+                    ControlFlow::Break(NotUniqueParam::DuplicateParam(r.into()))
+                }
+            }
+            _ => ControlFlow::Break(NotUniqueParam::NotParam(r.into())),
+        }
+    }
+    fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> {
+        match c.val {
+            ty::ConstKind::Param(p) => {
+                if self.seen.insert(p.index) {
+                    ControlFlow::CONTINUE
+                } else {
+                    ControlFlow::Break(NotUniqueParam::DuplicateParam(c.into()))
+                }
+            }
+            _ => ControlFlow::Break(NotUniqueParam::NotParam(c.into())),
+        }
+    }
+}
+
+/// Lint impls of auto traits if they are likely to have
+/// unsound or surprising effects on auto impls.
+fn lint_auto_trait_impls(tcx: TyCtxt<'_>, trait_def_id: DefId, impls: &[LocalDefId]) {
+    let mut non_covering_impls = Vec::new();
+    for &impl_def_id in impls {
+        let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap();
+        if trait_ref.references_error() {
+            return;
+        }
+
+        if tcx.impl_polarity(impl_def_id) != ImplPolarity::Positive {
+            return;
+        }
+
+        assert_eq!(trait_ref.substs.len(), 1);
+        let self_ty = trait_ref.self_ty();
+        let (self_type_did, substs) = match self_ty.kind() {
+            ty::Adt(def, substs) => (def.did, substs),
+            _ => {
+                // FIXME: should also lint for stuff like `&i32` but
+                // considering that auto traits are unstable, that
+                // isn't too important for now as this only affects
+                // crates using `nightly`, and std.
+                continue;
+            }
+        };
+
+        // Impls which completely cover a given root type are fine as they
+        // disable auto impls entirely. So only lint if the substs
+        // are not a permutation of the identity substs.
+        match substs.visit_with(&mut AreUniqueParamsVisitor::default()) {
+            ControlFlow::Continue(()) => {} // ok
+            ControlFlow::Break(arg) => {
+                // Ideally:
+                //
+                // - compute the requirements for the auto impl candidate
+                // - check whether these are implied by the non covering impls
+                // - if not, emit the lint
+                //
+                // What we do here is a bit simpler:
+                //
+                // - badly check if an auto impl candidate definitely does not apply
+                //   for the given simplified type
+                // - if so, do not lint
+                if fast_reject_auto_impl(tcx, trait_def_id, self_ty) {
+                    // ok
+                } else {
+                    non_covering_impls.push((impl_def_id, self_type_did, arg));
+                }
+            }
+        }
+    }
+
+    for &(impl_def_id, self_type_did, arg) in &non_covering_impls {
+        tcx.struct_span_lint_hir(
+            lint::builtin::SUSPICIOUS_AUTO_TRAIT_IMPLS,
+            tcx.hir().local_def_id_to_hir_id(impl_def_id),
+            tcx.def_span(impl_def_id),
+            |err| {
+                let mut err = err.build(&format!(
+                    "cross-crate traits with a default impl, like `{}`, \
+                         should not be specialized",
+                    tcx.def_path_str(trait_def_id),
+                ));
+                let item_span = tcx.def_span(self_type_did);
+                let self_descr = tcx.def_kind(self_type_did).descr(self_type_did);
+                err.span_note(
+                    item_span,
+                    &format!(
+                        "try using the same sequence of generic parameters as the {} definition",
+                        self_descr,
+                    ),
+                );
+                match arg {
+                    NotUniqueParam::DuplicateParam(arg) => {
+                        err.note(&format!("`{}` is mentioned multiple times", arg));
+                    }
+                    NotUniqueParam::NotParam(arg) => {
+                        err.note(&format!("`{}` is not a generic parameter", arg));
+                    }
+                }
+                err.emit();
+            },
+        );
+    }
+}
+
+fn fast_reject_auto_impl<'tcx>(tcx: TyCtxt<'tcx>, trait_def_id: DefId, self_ty: Ty<'tcx>) -> bool {
+    struct DisableAutoTraitVisitor<'tcx> {
+        tcx: TyCtxt<'tcx>,
+        trait_def_id: DefId,
+        self_ty_root: Ty<'tcx>,
+        seen: FxHashSet<DefId>,
+    }
+
+    impl<'tcx> TypeVisitor<'tcx> for DisableAutoTraitVisitor<'tcx> {
+        type BreakTy = ();
+        fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+            let tcx = self.tcx;
+            if t != self.self_ty_root {
+                for impl_def_id in tcx.non_blanket_impls_for_ty(self.trait_def_id, t) {
+                    match tcx.impl_polarity(impl_def_id) {
+                        ImplPolarity::Negative => return ControlFlow::BREAK,
+                        ImplPolarity::Reservation => {}
+                        // FIXME(@lcnr): That's probably not good enough, idk
+                        //
+                        // We might just want to take the rustdoc code and somehow avoid
+                        // explicit impls for `Self`.
+                        ImplPolarity::Positive => return ControlFlow::CONTINUE,
+                    }
+                }
+            }
+
+            match t.kind() {
+                ty::Adt(def, substs) => {
+                    // @lcnr: This is the only place where cycles can happen. We avoid this
+                    // by only visiting each `DefId` once.
+                    //
+                    // This will be is incorrect in subtle cases, but I don't care :)
+                    if self.seen.insert(def.did) {
+                        for ty in def.all_fields().map(|field| field.ty(tcx, substs)) {
+                            ty.visit_with(self)?;
+                        }
+                    }
+
+                    ControlFlow::CONTINUE
+                }
+                _ => t.super_visit_with(self),
+            }
+        }
+    }
+
+    let self_ty_root = match self_ty.kind() {
+        ty::Adt(def, _) => tcx.mk_adt(def, InternalSubsts::identity_for_item(tcx, def.did)),
+        _ => unimplemented!("unexpected self ty {:?}", self_ty),
+    };
+
+    self_ty_root
+        .visit_with(&mut DisableAutoTraitVisitor {
+            tcx,
+            self_ty_root,
+            trait_def_id,
+            seen: FxHashSet::default(),
+        })
+        .is_break()
+}
diff --git a/compiler/rustc_typeck/src/lib.rs b/compiler/rustc_typeck/src/lib.rs
index 6a9f154844a..7b004fa086b 100644
--- a/compiler/rustc_typeck/src/lib.rs
+++ b/compiler/rustc_typeck/src/lib.rs
@@ -69,6 +69,7 @@ This API is completely unstable and subject to change.
 #![feature(control_flow_enum)]
 #![feature(hash_drain_filter)]
 #![recursion_limit = "256"]
+#![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
 
 #[macro_use]
 extern crate tracing;