Auto merge of #121859 - matthiaskrgr:rollup-i724wpm, r=matthiaskrgr

Rollup of 12 pull requests

Successful merges:

 - #120646 (Fix incorrect suggestion for uninitialized binding in pattern)
 - #121416 (Improve error messages for generics with default parameters)
 - #121475 (Add tidy check for .stderr/.stdout files for non-existent test revisions)
 - #121580 (make unused_imports less assertive in test modules)
 - #121736 (Remove `Mutex::unlock` Function)
 - #121784 (Make the success arms of `if lhs || rhs` meet up in a separate block)
 - #121818 (CFI: Remove unused `typeid_for_fnsig`)
 - #121819 (Handle stashing of delayed bugs)
 - #121828 (Remove unused fluent messages)
 - #121831 (Fix typo in comment)
 - #121850 (Make `ZeroablePrimitive` trait unsafe.)
 - #121853 (normalizes-to: handle negative impls)

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

15 files changed, 109 insertions, 132 deletions

diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index 1e869ae924f..0776f455efd 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -613,7 +613,12 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     if self.sugg_span.is_some() {
                         return;
                     }
-                    if let hir::StmtKind::Local(hir::Local { span, ty, init: None, .. }) = &ex.kind
+
+                    // FIXME: We make sure that this is a normal top-level binding,
+                    // but we could suggest `todo!()` for all uninitalized bindings in the pattern pattern
+                    if let hir::StmtKind::Local(hir::Local { span, ty, init: None, pat, .. }) =
+                        &ex.kind
+                        && let hir::PatKind::Binding(..) = pat.kind
                         && span.contains(self.decl_span)
                     {
                         self.sugg_span = ty.map_or(Some(self.decl_span), |ty| Some(ty.span));
diff --git a/compiler/rustc_builtin_macros/messages.ftl b/compiler/rustc_builtin_macros/messages.ftl
index dda466b026d..bc2a9d5ad1e 100644
--- a/compiler/rustc_builtin_macros/messages.ftl
+++ b/compiler/rustc_builtin_macros/messages.ftl
@@ -221,12 +221,6 @@ builtin_macros_requires_cfg_pattern =
     macro requires a cfg-pattern as an argument
     .label = cfg-pattern required
 
-builtin_macros_should_panic = functions using `#[should_panic]` must return `()`
-
-builtin_macros_test_arg_non_lifetime = functions used as tests can not have any non-lifetime generic parameters
-
-builtin_macros_test_args = functions used as tests can not have any arguments
-
 builtin_macros_test_bad_fn = {$kind} functions cannot be used for tests
     .label = `{$kind}` because of this
 
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 0a533833e64..6b1ccbc5f7c 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -712,6 +712,7 @@ impl DiagCtxt {
     /// Stashes a diagnostic for possible later improvement in a different,
     /// later stage of the compiler. Possible actions depend on the diagnostic
     /// level:
+    /// - Level::Bug, Level:Fatal: not allowed, will trigger a panic.
     /// - Level::Error: immediately counted as an error that has occurred, because it
     ///   is guaranteed to be emitted eventually. Can be later accessed with the
     ///   provided `span` and `key` through
@@ -719,26 +720,39 @@ impl DiagCtxt {
     ///   [`DiagCtxt::try_steal_replace_and_emit_err`]. These do not allow
     ///   cancellation or downgrading of the error. Returns
     ///   `Some(ErrorGuaranteed)`.
+    /// - Level::DelayedBug: this does happen occasionally with errors that are
+    ///   downgraded to delayed bugs. It is not stashed, but immediately
+    ///   emitted as a delayed bug. This is because stashing it would cause it
+    ///   to be counted by `err_count` which we don't want. It doesn't matter
+    ///   that we cannot steal and improve it later, because it's not a
+    ///   user-facing error. Returns `Some(ErrorGuaranteed)` as is normal for
+    ///   delayed bugs.
     /// - Level::Warning and lower (i.e. !is_error()): can be accessed with the
     ///   provided `span` and `key` through [`DiagCtxt::steal_non_err()`]. This
     ///   allows cancelling and downgrading of the diagnostic. Returns `None`.
-    /// - Others: not allowed, will trigger a panic.
     pub fn stash_diagnostic(
         &self,
         span: Span,
         key: StashKey,
         diag: DiagInner,
     ) -> Option<ErrorGuaranteed> {
-        let guar = if diag.level() == Level::Error {
-            // This `unchecked_error_guaranteed` is valid. It is where the
-            // `ErrorGuaranteed` for stashed errors originates. See
-            // `DiagCtxtInner::drop`.
-            #[allow(deprecated)]
-            Some(ErrorGuaranteed::unchecked_error_guaranteed())
-        } else if !diag.is_error() {
-            None
-        } else {
-            self.span_bug(span, format!("invalid level in `stash_diagnostic`: {}", diag.level));
+        let guar = match diag.level {
+            Bug | Fatal => {
+                self.span_bug(
+                    span,
+                    format!("invalid level in `stash_diagnostic`: {:?}", diag.level),
+                );
+            }
+            Error => {
+                // This `unchecked_error_guaranteed` is valid. It is where the
+                // `ErrorGuaranteed` for stashed errors originates. See
+                // `DiagCtxtInner::drop`.
+                #[allow(deprecated)]
+                Some(ErrorGuaranteed::unchecked_error_guaranteed())
+            }
+            DelayedBug => return self.inner.borrow_mut().emit_diagnostic(diag),
+            ForceWarning(_) | Warning | Note | OnceNote | Help | OnceHelp | FailureNote | Allow
+            | Expect(_) => None,
         };
 
         // FIXME(Centril, #69537): Consider reintroducing panic on overwriting a stashed diagnostic
@@ -780,11 +794,11 @@ impl DiagCtxt {
         let err = self.inner.borrow_mut().stashed_diagnostics.swap_remove(&key);
         err.map(|(err, guar)| {
             // The use of `::<ErrorGuaranteed>` is safe because level is `Level::Error`.
-            assert_eq!(err.level, Level::Error);
+            assert_eq!(err.level, Error);
             assert!(guar.is_some());
             let mut err = Diag::<ErrorGuaranteed>::new_diagnostic(self, err);
             modify_err(&mut err);
-            assert_eq!(err.level, Level::Error);
+            assert_eq!(err.level, Error);
             err.emit()
         })
     }
@@ -803,7 +817,7 @@ impl DiagCtxt {
         let old_err = self.inner.borrow_mut().stashed_diagnostics.swap_remove(&key);
         match old_err {
             Some((old_err, guar)) => {
-                assert_eq!(old_err.level, Level::Error);
+                assert_eq!(old_err.level, Error);
                 assert!(guar.is_some());
                 // Because `old_err` has already been counted, it can only be
                 // safely cancelled because the `new_err` supplants it.
@@ -1367,7 +1381,7 @@ impl DiagCtxtInner {
         }
 
         if diagnostic.has_future_breakage() {
-            // Future breakages aren't emitted if they're Level::Allow,
+            // Future breakages aren't emitted if they're `Level::Allow`,
             // but they still need to be constructed and stashed below,
             // so they'll trigger the must_produce_diag check.
             self.suppressed_expected_diag = true;
@@ -1453,7 +1467,7 @@ impl DiagCtxtInner {
                 diagnostic.children.extract_if(already_emitted_sub).for_each(|_| {});
                 if already_emitted {
                     let msg = "duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`";
-                    diagnostic.sub(Level::Note, msg, MultiSpan::new());
+                    diagnostic.sub(Note, msg, MultiSpan::new());
                 }
 
                 if is_error {
@@ -1623,7 +1637,7 @@ impl DiagCtxtInner {
                 bug.arg("level", bug.level);
                 let msg = crate::fluent_generated::errors_invalid_flushed_delayed_diagnostic_level;
                 let msg = self.eagerly_translate_for_subdiag(&bug, msg); // after the `arg` call
-                bug.sub(Level::Note, msg, bug.span.primary_span().unwrap().into());
+                bug.sub(Note, msg, bug.span.primary_span().unwrap().into());
             }
             bug.level = Bug;
 
@@ -1671,7 +1685,7 @@ impl DelayedDiagInner {
         diag.arg("emitted_at", diag.emitted_at.clone());
         diag.arg("note", self.note);
         let msg = dcx.eagerly_translate_for_subdiag(&diag, msg); // after the `arg` calls
-        diag.sub(Level::Note, msg, diag.span.primary_span().unwrap_or(DUMMY_SP).into());
+        diag.sub(Note, msg, diag.span.primary_span().unwrap_or(DUMMY_SP).into());
         diag
     }
 }
diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl
index 89cd37e757f..e376411cd95 100644
--- a/compiler/rustc_hir_analysis/messages.ftl
+++ b/compiler/rustc_hir_analysis/messages.ftl
@@ -239,8 +239,6 @@ hir_analysis_missing_one_of_trait_item = not all trait items implemented, missin
     .label = missing one of `{$missing_items_msg}` in implementation
     .note = required because of this annotation
 
-hir_analysis_missing_tilde_const = missing `~const` qualifier for specialization
-
 hir_analysis_missing_trait_item = not all trait items implemented, missing: `{$missing_items_msg}`
     .label = missing `{$missing_items_msg}` in implementation
 
diff --git a/compiler/rustc_hir_analysis/src/astconv/lint.rs b/compiler/rustc_hir_analysis/src/astconv/lint.rs
index 227254b4cc8..fb5f3426cea 100644
--- a/compiler/rustc_hir_analysis/src/astconv/lint.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/lint.rs
@@ -1,5 +1,5 @@
 use rustc_ast::TraitObjectSyntax;
-use rustc_errors::{codes::*, Diag, EmissionGuarantee, Level, StashKey};
+use rustc_errors::{codes::*, Diag, EmissionGuarantee, StashKey};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_lint_defs::{builtin::BARE_TRAIT_OBJECTS, Applicability};
@@ -237,15 +237,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 }
                 // check if the impl trait that we are considering is a impl of a local trait
                 self.maybe_lint_blanket_trait_impl(self_ty, &mut diag);
-                match diag.level() {
-                    Level::Error => {
-                        diag.stash(self_ty.span, StashKey::TraitMissingMethod);
-                    }
-                    Level::DelayedBug => {
-                        diag.emit();
-                    }
-                    _ => unreachable!(),
-                }
+                diag.stash(self_ty.span, StashKey::TraitMissingMethod);
             } else {
                 let msg = "trait objects without an explicit `dyn` are deprecated";
                 tcx.node_span_lint(BARE_TRAIT_OBJECTS, self_ty.hir_id, self_ty.span, msg, |lint| {
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index 1cf990fef04..af1aa346c09 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -1247,10 +1247,23 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             (&ty::Adt(def1, sub1), &ty::Adt(def2, sub2)) => {
                 let did1 = def1.did();
                 let did2 = def2.did();
-                let sub_no_defaults_1 =
-                    self.tcx.generics_of(did1).own_args_no_defaults(self.tcx, sub1);
-                let sub_no_defaults_2 =
-                    self.tcx.generics_of(did2).own_args_no_defaults(self.tcx, sub2);
+
+                let generics1 = self.tcx.generics_of(did1);
+                let generics2 = self.tcx.generics_of(did2);
+
+                let non_default_after_default = generics1
+                    .check_concrete_type_after_default(self.tcx, sub1)
+                    || generics2.check_concrete_type_after_default(self.tcx, sub2);
+                let sub_no_defaults_1 = if non_default_after_default {
+                    generics1.own_args(sub1)
+                } else {
+                    generics1.own_args_no_defaults(self.tcx, sub1)
+                };
+                let sub_no_defaults_2 = if non_default_after_default {
+                    generics2.own_args(sub2)
+                } else {
+                    generics2.own_args_no_defaults(self.tcx, sub2)
+                };
                 let mut values = (DiagStyledString::new(), DiagStyledString::new());
                 let path1 = self.tcx.def_path_str(did1);
                 let path2 = self.tcx.def_path_str(did2);
diff --git a/compiler/rustc_lint/src/context/diagnostics.rs b/compiler/rustc_lint/src/context/diagnostics.rs
index 14e4c79563b..728996f0741 100644
--- a/compiler/rustc_lint/src/context/diagnostics.rs
+++ b/compiler/rustc_lint/src/context/diagnostics.rs
@@ -104,7 +104,7 @@ pub(super) fn builtin(sess: &Session, diagnostic: BuiltinLintDiagnostics, diag:
             if let Some(span) = in_test_module {
                 diag.span_help(
                     sess.source_map().guess_head_span(span),
-                    "consider adding a `#[cfg(test)]` to the containing module",
+                    "if this is a test module, consider adding a `#[cfg(test)]` to the containing module",
                 );
             }
         }
diff --git a/compiler/rustc_middle/src/ty/generics.rs b/compiler/rustc_middle/src/ty/generics.rs
index c81d9dfbc7d..2630b96869b 100644
--- a/compiler/rustc_middle/src/ty/generics.rs
+++ b/compiler/rustc_middle/src/ty/generics.rs
@@ -360,6 +360,30 @@ impl<'tcx> Generics {
         let own = &args[self.parent_count..][..self.params.len()];
         if self.has_self && self.parent.is_none() { &own[1..] } else { own }
     }
+
+    /// Returns true if a concrete type is specified after a default type.
+    /// For example, consider `struct T<W = usize, X = Vec<W>>(W, X)`
+    /// `T<usize, String>` will return true
+    /// `T<usize>` will return false
+    pub fn check_concrete_type_after_default(
+        &'tcx self,
+        tcx: TyCtxt<'tcx>,
+        args: &'tcx [ty::GenericArg<'tcx>],
+    ) -> bool {
+        let mut default_param_seen = false;
+        for param in self.params.iter() {
+            if let Some(inst) =
+                param.default_value(tcx).map(|default| default.instantiate(tcx, args))
+            {
+                if inst == args[param.index as usize] {
+                    default_param_seen = true;
+                } else if default_param_seen {
+                    return true;
+                }
+            }
+        }
+        false
+    }
 }
 
 /// Bounds on generics.
diff --git a/compiler/rustc_mir_build/src/build/matches/mod.rs b/compiler/rustc_mir_build/src/build/matches/mod.rs
index 641a278c1d3..6cdb78d1a94 100644
--- a/compiler/rustc_mir_build/src/build/matches/mod.rs
+++ b/compiler/rustc_mir_build/src/build/matches/mod.rs
@@ -93,8 +93,14 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     variable_source_info,
                     true,
                 ));
-                this.cfg.goto(lhs_success_block, variable_source_info, rhs_success_block);
-                rhs_success_block.unit()
+
+                // Make the LHS and RHS success arms converge to a common block.
+                // (We can't just make LHS goto RHS, because `rhs_success_block`
+                // might contain statements that we don't want on the LHS path.)
+                let success_block = this.cfg.start_new_block();
+                this.cfg.goto(lhs_success_block, variable_source_info, success_block);
+                this.cfg.goto(rhs_success_block, variable_source_info, success_block);
+                success_block.unit()
             }
             ExprKind::Unary { op: UnOp::Not, arg } => {
                 let local_scope = this.local_scope();
diff --git a/compiler/rustc_mir_transform/src/known_panics_lint.rs b/compiler/rustc_mir_transform/src/known_panics_lint.rs
index 7cab6650994..27477769cef 100644
--- a/compiler/rustc_mir_transform/src/known_panics_lint.rs
+++ b/compiler/rustc_mir_transform/src/known_panics_lint.rs
@@ -586,7 +586,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             }
 
             Aggregate(ref kind, ref fields) => {
-                // Do not const pop union fields as they can be
+                // Do not const prop union fields as they can be
                 // made to produce values that don't match their
                 // underlying layout's type (see ICE #121534).
                 // If the last element of the `Adt` tuple
diff --git a/compiler/rustc_parse/messages.ftl b/compiler/rustc_parse/messages.ftl
index 55baf6f9f2e..60cc138fd7b 100644
--- a/compiler/rustc_parse/messages.ftl
+++ b/compiler/rustc_parse/messages.ftl
@@ -284,9 +284,6 @@ parse_found_expr_would_be_stmt = expected expression, found `{$token}`
 parse_function_body_equals_expr = function body cannot be `= expression;`
     .suggestion = surround the expression with `{"{"}` and `{"}"}` instead of `=` and `;`
 
-parse_gen_fn = `gen` functions are not yet implemented
-    .help = for now you can use `gen {"{}"}` blocks and return `impl Iterator` instead
-
 parse_generic_args_in_pat_require_turbofish_syntax = generic args in patterns require the turbofish syntax
 
 parse_generic_parameters_without_angle_brackets = generic parameters without surrounding angle brackets
diff --git a/compiler/rustc_resolve/messages.ftl b/compiler/rustc_resolve/messages.ftl
index 0747685c35c..fa98338bbb6 100644
--- a/compiler/rustc_resolve/messages.ftl
+++ b/compiler/rustc_resolve/messages.ftl
@@ -8,10 +8,6 @@ resolve_add_as_non_derive =
 resolve_added_macro_use =
     have you added the `#[macro_use]` on the module/import?
 
-resolve_ampersand_used_without_explicit_lifetime_name =
-    `&` without an explicit lifetime name cannot be used here
-    .note = explicit lifetime name needed here
-
 resolve_ancestor_only =
     visibilities can only be restricted to ancestor modules
 
@@ -100,12 +96,6 @@ resolve_const_param_in_non_trivial_anon_const =
 resolve_const_param_in_ty_of_const_param =
     const parameters may not be used in the type of const parameters
 
-resolve_crate_may_not_be_imported =
-    `$crate` may not be imported
-
-resolve_crate_root_imports_must_be_named_explicitly =
-    crate root imports need to be explicitly named: `use crate as name;`
-
 resolve_expected_found =
     expected module, found {$res} `{$path_str}`
     .label = not a module
@@ -220,9 +210,6 @@ resolve_param_in_ty_of_const_param =
     the type of const parameters must not depend on other generic parameters
     .label = the type must not depend on the parameter `{$name}`
 
-resolve_parent_module_reset_for_binding =
-    parent module is reset for binding
-
 resolve_proc_macro_same_crate = can't use a procedural macro from the same crate that defines it
     .help = you can define integration tests in a directory named `tests`
 
@@ -270,11 +257,6 @@ resolve_trait_impl_duplicate =
     .old_span_label = previous definition here
     .trait_item_span = item in trait
 
-resolve_trait_impl_mismatch =
-    item `{$name}` is an associated {$kind}, which doesn't match its trait `{$trait_path}`
-    .label = does not match trait
-    .label_trait_item = item in trait
-
 resolve_try_using_similarly_named_label =
     try using similarly named label
 
@@ -295,10 +277,6 @@ resolve_undeclared_label =
     use of undeclared label `{$name}`
     .label = undeclared label `{$name}`
 
-resolve_underscore_lifetime_name_cannot_be_used_here =
-    `'_` cannot be used here
-    .note = `'_` is a reserved lifetime name
-
 resolve_unexpected_res_change_ty_to_const_param_sugg =
     you might have meant to write a const parameter here
 
diff --git a/compiler/rustc_symbol_mangling/src/typeid.rs b/compiler/rustc_symbol_mangling/src/typeid.rs
index 838d9d774b2..e8763e49e62 100644
--- a/compiler/rustc_symbol_mangling/src/typeid.rs
+++ b/compiler/rustc_symbol_mangling/src/typeid.rs
@@ -4,13 +4,13 @@
 /// For more information about LLVM CFI and cross-language LLVM CFI support for the Rust compiler,
 /// see design document in the tracking issue #89653.
 use bitflags::bitflags;
-use rustc_middle::ty::{FnSig, Instance, Ty, TyCtxt};
+use rustc_middle::ty::{Instance, Ty, TyCtxt};
 use rustc_target::abi::call::FnAbi;
 use std::hash::Hasher;
 use twox_hash::XxHash64;
 
 bitflags! {
-    /// Options for typeid_for_fnabi and typeid_for_fnsig.
+    /// Options for typeid_for_fnabi.
     #[derive(Clone, Copy, Debug)]
     pub struct TypeIdOptions: u32 {
         const GENERALIZE_POINTERS = 1;
@@ -30,15 +30,6 @@ pub fn typeid_for_fnabi<'tcx>(
     typeid_itanium_cxx_abi::typeid_for_fnabi(tcx, fn_abi, options)
 }
 
-/// Returns a type metadata identifier for the specified FnSig.
-pub fn typeid_for_fnsig<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    fn_sig: &FnSig<'tcx>,
-    options: TypeIdOptions,
-) -> String {
-    typeid_itanium_cxx_abi::typeid_for_fnsig(tcx, fn_sig, options)
-}
-
 /// Returns a type metadata identifier for the specified Instance.
 pub fn typeid_for_instance<'tcx>(
     tcx: TyCtxt<'tcx>,
@@ -61,19 +52,6 @@ pub fn kcfi_typeid_for_fnabi<'tcx>(
     hash.finish() as u32
 }
 
-/// Returns a KCFI type metadata identifier for the specified FnSig.
-pub fn kcfi_typeid_for_fnsig<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    fn_sig: &FnSig<'tcx>,
-    options: TypeIdOptions,
-) -> u32 {
-    // A KCFI type metadata identifier is a 32-bit constant produced by taking the lower half of the
-    // xxHash64 of the type metadata identifier. (See llvm/llvm-project@cff5bef.)
-    let mut hash: XxHash64 = Default::default();
-    hash.write(typeid_itanium_cxx_abi::typeid_for_fnsig(tcx, fn_sig, options).as_bytes());
-    hash.finish() as u32
-}
-
 /// Returns a KCFI type metadata identifier for the specified Instance.
 pub fn kcfi_typeid_for_instance<'tcx>(
     tcx: TyCtxt<'tcx>,
diff --git a/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs b/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
index b5b3aa27060..87422042180 100644
--- a/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
+++ b/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
@@ -1074,41 +1074,6 @@ pub fn typeid_for_fnabi<'tcx>(
     typeid
 }
 
-/// Returns a type metadata identifier for the specified FnSig using the Itanium C++ ABI with vendor
-/// extended type qualifiers and types for Rust types that are not used at the FFI boundary.
-pub fn typeid_for_fnsig<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    fn_sig: &FnSig<'tcx>,
-    options: TypeIdOptions,
-) -> String {
-    // A name is mangled by prefixing "_Z" to an encoding of its name, and in the case of functions
-    // its type.
-    let mut typeid = String::from("_Z");
-
-    // Clang uses the Itanium C++ ABI's virtual tables and RTTI typeinfo structure name as type
-    // metadata identifiers for function pointers. The typeinfo name encoding is a two-character
-    // code (i.e., 'TS') prefixed to the type encoding for the function.
-    typeid.push_str("TS");
-
-    // A dictionary of substitution candidates used for compression (see
-    // https://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangling-compression).
-    let mut dict: FxHashMap<DictKey<'tcx>, usize> = FxHashMap::default();
-
-    // Encode the function signature
-    typeid.push_str(&encode_fnsig(tcx, fn_sig, &mut dict, options));
-
-    // Add encoding suffixes
-    if options.contains(EncodeTyOptions::NORMALIZE_INTEGERS) {
-        typeid.push_str(".normalized");
-    }
-
-    if options.contains(EncodeTyOptions::GENERALIZE_POINTERS) {
-        typeid.push_str(".generalized");
-    }
-
-    typeid
-}
-
 /// Returns a type metadata identifier for the specified Instance using the Itanium C++ ABI with
 /// vendor extended type qualifiers and types for Rust types that are not used at the FFI boundary.
 pub fn typeid_for_instance<'tcx>(
diff --git a/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs b/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
index 3aba5c85abc..248985715c2 100644
--- a/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
+++ b/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
@@ -162,15 +162,28 @@ impl<'tcx> assembly::GoalKind<'tcx> for NormalizesTo<'tcx> {
         let tcx = ecx.tcx();
 
         let goal_trait_ref = goal.predicate.alias.trait_ref(tcx);
-        let impl_trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap();
+        let impl_trait_header = tcx.impl_trait_header(impl_def_id).unwrap();
         let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::ForLookup };
-        if !drcx.args_may_unify(goal_trait_ref.args, impl_trait_ref.skip_binder().args) {
+        if !drcx.args_may_unify(
+            goal.predicate.trait_ref(tcx).args,
+            impl_trait_header.skip_binder().trait_ref.args,
+        ) {
             return Err(NoSolution);
         }
 
+        // We have to ignore negative impls when projecting.
+        let impl_polarity = impl_trait_header.skip_binder().polarity;
+        match impl_polarity {
+            ty::ImplPolarity::Negative => return Err(NoSolution),
+            ty::ImplPolarity::Reservation => {
+                unimplemented!("reservation impl for trait with assoc item: {:?}", goal)
+            }
+            ty::ImplPolarity::Positive => {}
+        };
+
         ecx.probe_trait_candidate(CandidateSource::Impl(impl_def_id)).enter(|ecx| {
             let impl_args = ecx.fresh_args_for_item(impl_def_id);
-            let impl_trait_ref = impl_trait_ref.instantiate(tcx, impl_args);
+            let impl_trait_ref = impl_trait_header.instantiate(tcx, impl_args).trait_ref;
 
             ecx.eq(goal.param_env, goal_trait_ref, impl_trait_ref)?;