Auto merge of #112805 - matthiaskrgr:rollup-r5yrefu, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #109970 ([doc] `poll_fn`: explain how to `pin` captured state safely)
 - #112705 (Simplify `Span::source_callee` impl)
 - #112757 (Use BorrowFlag instead of explicit isize)
 - #112768 (Rewrite various resolve/diagnostics errors as translatable diagnostics)
 - #112777 (Continue folding in query normalizer on weak aliases)
 - #112780 (Treat TAIT equation as always ambiguous in coherence)
 - #112783 (Don't ICE on bound var in `reject_fn_ptr_impls`)

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

compiler/rustc_infer/src/infer/combine.rs

@@ -124,13 +124,10 @@ impl<'tcx> InferCtxt<'tcx> {
             }
 
             // During coherence, opaque types should be treated as *possibly*
-            // equal to each other, even if their generic params differ, as
-            // they could resolve to the same hidden type, even for different
-            // generic params.
-            (
-                &ty::Alias(ty::Opaque, ty::AliasTy { def_id: a_def_id, .. }),
-                &ty::Alias(ty::Opaque, ty::AliasTy { def_id: b_def_id, .. }),
-            ) if self.intercrate && a_def_id == b_def_id => {
+            // equal to any other type (except for possibly itself). This is an
+            // extremely heavy hammer, but can be relaxed in a fowards-compatible
+            // way later.
+            (&ty::Alias(ty::Opaque, _), _) | (_, &ty::Alias(ty::Opaque, _)) if self.intercrate => {
                 relation.register_predicates([ty::Binder::dummy(ty::PredicateKind::Ambiguous)]);
                 Ok(a)
             }

compiler/rustc_resolve/messages.ftl

@@ -5,6 +5,9 @@ resolve_add_as_non_derive =
     add as non-Derive macro
     `#[{$macro_path}]`
 
+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
@@ -45,9 +48,18 @@ resolve_cannot_capture_dynamic_environment_in_fn_item =
     can't capture dynamic environment in a fn item
     .help = use the `|| {"{"} ... {"}"}` closure form instead
 
+resolve_cannot_find_ident_in_this_scope =
+    cannot find {$expected} `{$ident}` in this scope
+
 resolve_cannot_use_self_type_here =
     can't use `Self` here
 
+resolve_change_import_binding =
+    you can use `as` to change the binding name of the import
+
+resolve_consider_adding_a_derive =
+    consider adding a derive
+
 resolve_const_not_member_of_trait =
     const `{$const_}` is not a member of trait `{$trait_}`
     .label = not a member of trait `{$trait_}`
@@ -74,6 +86,9 @@ resolve_expected_found =
     expected module, found {$res} `{$path_str}`
     .label = not a module
 
+resolve_explicit_unsafe_traits =
+    unsafe traits like `{$ident}` should be implemented explicitly
+
 resolve_forward_declared_generic_param =
     generic parameters with a default cannot use forward declared identifiers
     .label = defaulted generic parameters cannot be forward declared
@@ -96,6 +111,9 @@ resolve_ident_bound_more_than_once_in_same_pattern =
 
 resolve_imported_crate = `$crate` may not be imported
 
+resolve_imports_cannot_refer_to =
+    imports cannot refer to {$what}
+
 resolve_indeterminate =
     cannot determine resolution for the visibility
 

compiler/rustc_resolve/src/diagnostics.rs

@@ -30,6 +30,10 @@ use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{BytePos, Span, SyntaxContext};
 use thin_vec::ThinVec;
 
+use crate::errors::{
+    AddedMacroUse, ChangeImportBinding, ChangeImportBindingSuggestion, ConsiderAddingADerive,
+    ExplicitUnsafeTraits,
+};
 use crate::imports::{Import, ImportKind};
 use crate::late::{PatternSource, Rib};
 use crate::path_names_to_string;
@@ -376,16 +380,10 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             _ => unreachable!(),
         }
 
-        let rename_msg = "you can use `as` to change the binding name of the import";
         if let Some(suggestion) = suggestion {
-            err.span_suggestion(
-                binding_span,
-                rename_msg,
-                suggestion,
-                Applicability::MaybeIncorrect,
-            );
+            err.subdiagnostic(ChangeImportBindingSuggestion { span: binding_span, suggestion });
         } else {
-            err.span_label(binding_span, rename_msg);
+            err.subdiagnostic(ChangeImportBinding { span: binding_span });
         }
     }
 
@@ -1382,12 +1380,11 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         );
 
         if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) {
-            let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
-            err.span_note(ident.span, msg);
+            err.subdiagnostic(ExplicitUnsafeTraits { span: ident.span, ident });
             return;
         }
         if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
-            err.help("have you added the `#[macro_use]` on the module/import?");
+            err.subdiagnostic(AddedMacroUse);
             return;
         }
         if ident.name == kw::Default
@@ -1396,14 +1393,10 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             let span = self.def_span(def_id);
             let source_map = self.tcx.sess.source_map();
             let head_span = source_map.guess_head_span(span);
-            if let Ok(head) = source_map.span_to_snippet(head_span) {
-                err.span_suggestion(head_span, "consider adding a derive", format!("#[derive(Default)]\n{head}"), Applicability::MaybeIncorrect);
-            } else {
-                err.span_help(
-                    head_span,
-                    "consider adding `#[derive(Default)]` to this enum",
-                );
-            }
+            err.subdiagnostic(ConsiderAddingADerive {
+                span: head_span.shrink_to_lo(),
+                suggestion: format!("#[derive(Default)]\n")
+            });
         }
         for ns in [Namespace::MacroNS, Namespace::TypeNS, Namespace::ValueNS] {
             if let Ok(binding) = self.early_resolve_ident_in_lexical_scope(

compiler/rustc_resolve/src/errors.rs

@@ -586,3 +586,63 @@ pub(crate) enum ParamKindInEnumDiscriminant {
     #[note(resolve_lifetime_param_in_enum_discriminant)]
     Lifetime,
 }
+
+#[derive(Subdiagnostic)]
+#[label(resolve_change_import_binding)]
+pub(crate) struct ChangeImportBinding {
+    #[primary_span]
+    pub(crate) span: Span,
+}
+
+#[derive(Subdiagnostic)]
+#[suggestion(
+    resolve_change_import_binding,
+    code = "{suggestion}",
+    applicability = "maybe-incorrect"
+)]
+pub(crate) struct ChangeImportBindingSuggestion {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) suggestion: String,
+}
+
+#[derive(Diagnostic)]
+#[diag(resolve_imports_cannot_refer_to)]
+pub(crate) struct ImportsCannotReferTo<'a> {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) what: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(resolve_cannot_find_ident_in_this_scope)]
+pub(crate) struct CannotFindIdentInThisScope<'a> {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) expected: &'a str,
+    pub(crate) ident: Ident,
+}
+
+#[derive(Subdiagnostic)]
+#[note(resolve_explicit_unsafe_traits)]
+pub(crate) struct ExplicitUnsafeTraits {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) ident: Ident,
+}
+
+#[derive(Subdiagnostic)]
+#[help(resolve_added_macro_use)]
+pub(crate) struct AddedMacroUse;
+
+#[derive(Subdiagnostic)]
+#[suggestion(
+    resolve_consider_adding_a_derive,
+    code = "{suggestion}",
+    applicability = "maybe-incorrect"
+)]
+pub(crate) struct ConsiderAddingADerive {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) suggestion: String,
+}

compiler/rustc_resolve/src/late.rs

@@ -6,6 +6,7 @@
 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
 //! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
 
+use crate::errors::ImportsCannotReferTo;
 use crate::BindingKey;
 use crate::{path_names_to_string, rustdoc, BindingError, Finalize, LexicalScopeBinding};
 use crate::{Module, ModuleOrUniformRoot, NameBinding, ParentScope, PathResult};
@@ -2244,12 +2245,13 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                 _ => &[TypeNS],
             };
             let report_error = |this: &Self, ns| {
-                let what = if ns == TypeNS { "type parameters" } else { "local variables" };
                 if this.should_report_errs() {
+                    let what = if ns == TypeNS { "type parameters" } else { "local variables" };
                     this.r
                         .tcx
                         .sess
-                        .span_err(ident.span, format!("imports cannot refer to {}", what));
+                        .create_err(ImportsCannotReferTo { span: ident.span, what })
+                        .emit();
                 }
             };
 

compiler/rustc_resolve/src/macros.rs

@@ -1,7 +1,9 @@
 //! A bunch of methods and structures more or less related to resolving macros and
 //! interface provided by `Resolver` to macro expander.
 
-use crate::errors::{self, AddAsNonDerive, MacroExpectedFound, RemoveSurroundingDerive};
+use crate::errors::{
+    self, AddAsNonDerive, CannotFindIdentInThisScope, MacroExpectedFound, RemoveSurroundingDerive,
+};
 use crate::Namespace::*;
 use crate::{BuiltinMacroState, Determinacy};
 use crate::{DeriveData, Finalize, ParentScope, ResolutionError, Resolver, ScopeSet};
@@ -793,8 +795,13 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                 }
                 Err(..) => {
                     let expected = kind.descr_expected();
-                    let msg = format!("cannot find {} `{}` in this scope", expected, ident);
-                    let mut err = self.tcx.sess.struct_span_err(ident.span, msg);
+
+                    let mut err = self.tcx.sess.create_err(CannotFindIdentInThisScope {
+                        span: ident.span,
+                        expected,
+                        ident,
+                    });
+
                     self.unresolved_macro_suggestions(&mut err, kind, &parent_scope, ident, krate);
                     err.emit();
                 }

compiler/rustc_span/src/lib.rs

@@ -65,11 +65,11 @@ use rustc_data_structures::sync::{Lock, Lrc};
 
 use std::borrow::Cow;
 use std::cmp::{self, Ordering};
-use std::fmt;
 use std::hash::Hash;
 use std::ops::{Add, Range, Sub};
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
+use std::{fmt, iter};
 
 use md5::Digest;
 use md5::Md5;
@@ -733,12 +733,15 @@ impl Span {
     /// else returns the `ExpnData` for the macro definition
     /// corresponding to the source callsite.
     pub fn source_callee(self) -> Option<ExpnData> {
-        fn source_callee(expn_data: ExpnData) -> ExpnData {
-            let next_expn_data = expn_data.call_site.ctxt().outer_expn_data();
-            if !next_expn_data.is_root() { source_callee(next_expn_data) } else { expn_data }
-        }
         let expn_data = self.ctxt().outer_expn_data();
-        if !expn_data.is_root() { Some(source_callee(expn_data)) } else { None }
+
+        // Create an iterator of call site expansions
+        iter::successors(Some(expn_data), |expn_data| {
+            Some(expn_data.call_site.ctxt().outer_expn_data())
+        })
+        // Find the last expansion which is not root
+        .take_while(|expn_data| !expn_data.is_root())
+        .last()
     }
 
     /// Checks if a span is "internal" to a macro in which `#[unstable]`
@@ -777,7 +780,7 @@ impl Span {
 
     pub fn macro_backtrace(mut self) -> impl Iterator<Item = ExpnData> {
         let mut prev_span = DUMMY_SP;
-        std::iter::from_fn(move || {
+        iter::from_fn(move || {
             loop {
                 let expn_data = self.ctxt().outer_expn_data();
                 if expn_data.is_root() {

compiler/rustc_trait_selection/src/traits/query/normalize.rs

@@ -322,8 +322,12 @@ impl<'cx, 'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for QueryNormalizer<'cx, 'tcx>
                 };
                 // `tcx.normalize_projection_ty` may normalize to a type that still has
                 // unevaluated consts, so keep normalizing here if that's the case.
-                if res != ty && res.has_type_flags(ty::TypeFlags::HAS_CT_PROJECTION) {
-                    res.try_super_fold_with(self)?
+                // Similarly, `tcx.normalize_weak_ty` will only unwrap one layer of type
+                // and we need to continue folding it to reveal the TAIT behind it.
+                if res != ty
+                    && (res.has_type_flags(ty::TypeFlags::HAS_CT_PROJECTION) || kind == ty::Weak)
+                {
+                    res.try_fold_with(self)?
                 } else {
                     res
                 }

compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs

@@ -417,17 +417,15 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 // Fast path to avoid evaluating an obligation that trivially holds.
                 // There may be more bounds, but these are checked by the regular path.
                 ty::FnPtr(..) => return false,
+
                 // These may potentially implement `FnPtr`
                 ty::Placeholder(..)
                 | ty::Dynamic(_, _, _)
                 | ty::Alias(_, _)
                 | ty::Infer(_)
-                | ty::Param(..) => {}
+                | ty::Param(..)
+                | ty::Bound(_, _) => {}
 
-                ty::Bound(_, _) => span_bug!(
-                    obligation.cause.span(),
-                    "cannot have escaping bound var in self type of {obligation:#?}"
-                ),
                 // These can't possibly implement `FnPtr` as they are concrete types
                 // and not `FnPtr`
                 ty::Bool

library/core/src/cell.rs

@@ -1374,7 +1374,7 @@ impl Clone for BorrowRef<'_> {
         debug_assert!(is_reading(borrow));
         // Prevent the borrow counter from overflowing into
         // a writing borrow.
-        assert!(borrow != isize::MAX);
+        assert!(borrow != BorrowFlag::MAX);
         self.borrow.set(borrow + 1);
         BorrowRef { borrow: self.borrow }
     }
@@ -1756,7 +1756,7 @@ impl<'b> BorrowRefMut<'b> {
         let borrow = self.borrow.get();
         debug_assert!(is_writing(borrow));
         // Prevent the borrow counter from underflowing.
-        assert!(borrow != isize::MIN);
+        assert!(borrow != BorrowFlag::MIN);
         self.borrow.set(borrow - 1);
         BorrowRefMut { borrow: self.borrow }
     }