Auto merge of #95351 - Dylan-DPC:rollup-o1il7tx, r=Dylan-DPC

Rollup of 5 pull requests

Successful merges:

 - #91981 (Recover suggestions and useful information lost in previous PR)
 - #93469 (Skip pointing out ambiguous impls in alloc/std crates too in inference errors)
 - #95335 (Move resolve_path to rustc_builtin_macros and make it private)
 - #95340 (interpret: with enforce_number_validity, ensure integers are truly Scalar::Int (i.e., no pointers))
 - #95341 (ARMv6K Horizon OS has_thread_local support)

Failed merges:

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

compiler/rustc_builtin_macros/src/source_util.rs

@@ -3,15 +3,17 @@ use rustc_ast::ptr::P;
 use rustc_ast::token;
 use rustc_ast::tokenstream::TokenStream;
 use rustc_ast_pretty::pprust;
+use rustc_errors::PResult;
 use rustc_expand::base::{self, *};
 use rustc_expand::module::DirOwnership;
 use rustc_parse::parser::{ForceCollect, Parser};
 use rustc_parse::{self, new_parser_from_file};
 use rustc_session::lint::builtin::INCOMPLETE_INCLUDE;
 use rustc_span::symbol::Symbol;
-use rustc_span::{self, Pos, Span};
+use rustc_span::{self, FileName, Pos, Span};
 
 use smallvec::SmallVec;
+use std::path::PathBuf;
 use std::rc::Rc;
 
 // These macros all relate to the file system; they either return
@@ -102,7 +104,7 @@ pub fn expand_include<'cx>(
         return DummyResult::any(sp);
     };
     // The file will be added to the code map by the parser
-    let file = match cx.resolve_path(file, sp) {
+    let file = match resolve_path(cx, file, sp) {
         Ok(f) => f,
         Err(mut err) => {
             err.emit();
@@ -171,7 +173,7 @@ pub fn expand_include_str(
     let Some(file) = get_single_str_from_tts(cx, sp, tts, "include_str!") else {
         return DummyResult::any(sp);
     };
-    let file = match cx.resolve_path(file, sp) {
+    let file = match resolve_path(cx, file, sp) {
         Ok(f) => f,
         Err(mut err) => {
             err.emit();
@@ -205,7 +207,7 @@ pub fn expand_include_bytes(
     let Some(file) = get_single_str_from_tts(cx, sp, tts, "include_bytes!") else {
         return DummyResult::any(sp);
     };
-    let file = match cx.resolve_path(file, sp) {
+    let file = match resolve_path(cx, file, sp) {
         Ok(f) => f,
         Err(mut err) => {
             err.emit();
@@ -220,3 +222,40 @@ pub fn expand_include_bytes(
         }
     }
 }
+
+/// Resolves a `path` mentioned inside Rust code, returning an absolute path.
+///
+/// This unifies the logic used for resolving `include_X!`.
+fn resolve_path<'a>(
+    cx: &mut ExtCtxt<'a>,
+    path: impl Into<PathBuf>,
+    span: Span,
+) -> PResult<'a, PathBuf> {
+    let path = path.into();
+
+    // Relative paths are resolved relative to the file in which they are found
+    // after macro expansion (that is, they are unhygienic).
+    if !path.is_absolute() {
+        let callsite = span.source_callsite();
+        let mut result = match cx.source_map().span_to_filename(callsite) {
+            FileName::Real(name) => name
+                .into_local_path()
+                .expect("attempting to resolve a file path in an external file"),
+            FileName::DocTest(path, _) => path,
+            other => {
+                return Err(cx.struct_span_err(
+                    span,
+                    &format!(
+                        "cannot resolve relative path in non-file source `{}`",
+                        cx.source_map().filename_for_diagnostics(&other)
+                    ),
+                ));
+            }
+        };
+        result.pop();
+        result.push(path);
+        Ok(result)
+    } else {
+        Ok(path)
+    }
+}

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -444,6 +444,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         match scalar.try_to_int() {
             Ok(int) => int.is_null(),
             Err(_) => {
+                // Can only happen during CTFE.
                 let ptr = self.scalar_to_ptr(scalar);
                 match self.memory.ptr_try_get_alloc(ptr) {
                     Ok((alloc_id, offset, _)) => {
@@ -455,7 +456,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         // Note that one-past-the-end (offset == size) is still inbounds, and never null.
                         offset > size
                     }
-                    Err(offset) => offset == 0,
+                    Err(_offset) => bug!("a non-int scalar is always a pointer"),
                 }
             }
         }

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -21,7 +21,7 @@ use std::hash::Hash;
 
 use super::{
     alloc_range, CheckInAllocMsg, GlobalAlloc, InterpCx, InterpResult, MPlaceTy, Machine,
-    MemPlaceMeta, OpTy, ScalarMaybeUninit, ValueVisitor,
+    MemPlaceMeta, OpTy, Scalar, ScalarMaybeUninit, ValueVisitor,
 };
 
 macro_rules! throw_validation_failure {
@@ -521,8 +521,11 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                 // NOTE: Keep this in sync with the array optimization for int/float
                 // types below!
                 if M::enforce_number_validity(self.ecx) {
-                    // Integers/floats in CTFE: Must be scalar bits, pointers are dangerous
-                    let is_bits = value.check_init().map_or(false, |v| v.try_to_int().is_ok());
+                    // Integers/floats with number validity: Must be scalar bits, pointers are dangerous.
+                    // As a special exception we *do* match on a `Scalar` here, since we truly want
+                    // to know its underlying representation (and *not* cast it to an integer).
+                    let is_bits =
+                        value.check_init().map_or(false, |v| matches!(v, Scalar::Int(..)));
                     if !is_bits {
                         throw_validation_failure!(self.path,
                             { "{:x}", value } expected { "initialized plain (non-pointer) bytes" }

compiler/rustc_expand/src/base.rs

@@ -10,7 +10,7 @@ use rustc_ast::{self as ast, AstLike, Attribute, Item, NodeId, PatKind};
 use rustc_attr::{self as attr, Deprecation, Stability};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::{self, Lrc};
-use rustc_errors::{Applicability, DiagnosticBuilder, ErrorGuaranteed, PResult};
+use rustc_errors::{Applicability, DiagnosticBuilder, ErrorGuaranteed};
 use rustc_lint_defs::builtin::PROC_MACRO_BACK_COMPAT;
 use rustc_lint_defs::BuiltinLintDiagnostics;
 use rustc_parse::{self, nt_to_tokenstream, parser, MACRO_ARGUMENTS};
@@ -20,7 +20,7 @@ use rustc_span::edition::Edition;
 use rustc_span::hygiene::{AstPass, ExpnData, ExpnKind, LocalExpnId};
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
-use rustc_span::{FileName, MultiSpan, Span, DUMMY_SP};
+use rustc_span::{MultiSpan, Span, DUMMY_SP};
 use smallvec::{smallvec, SmallVec};
 
 use std::default::Default;
@@ -1128,41 +1128,6 @@ impl<'a> ExtCtxt<'a> {
     pub fn check_unused_macros(&mut self) {
         self.resolver.check_unused_macros();
     }
-
-    /// Resolves a `path` mentioned inside Rust code, returning an absolute path.
-    ///
-    /// This unifies the logic used for resolving `include_X!`.
-    ///
-    /// FIXME: move this to `rustc_builtin_macros` and make it private.
-    pub fn resolve_path(&self, path: impl Into<PathBuf>, span: Span) -> PResult<'a, PathBuf> {
-        let path = path.into();
-
-        // Relative paths are resolved relative to the file in which they are found
-        // after macro expansion (that is, they are unhygienic).
-        if !path.is_absolute() {
-            let callsite = span.source_callsite();
-            let mut result = match self.source_map().span_to_filename(callsite) {
-                FileName::Real(name) => name
-                    .into_local_path()
-                    .expect("attempting to resolve a file path in an external file"),
-                FileName::DocTest(path, _) => path,
-                other => {
-                    return Err(self.struct_span_err(
-                        span,
-                        &format!(
-                            "cannot resolve relative path in non-file source `{}`",
-                            self.source_map().filename_for_diagnostics(&other)
-                        ),
-                    ));
-                }
-            };
-            result.pop();
-            result.push(path);
-            Ok(result)
-        } else {
-            Ok(path)
-        }
-    }
 }
 
 /// Extracts a string literal from the macro expanded version of `expr`,

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -333,6 +333,9 @@ pub fn same_type_modulo_infer<'tcx>(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
         )
         | (&ty::Infer(ty::InferTy::TyVar(_)), _)
         | (_, &ty::Infer(ty::InferTy::TyVar(_))) => true,
+        (&ty::Ref(reg_a, ty_a, mut_a), &ty::Ref(reg_b, ty_b, mut_b)) => {
+            reg_a == reg_b && mut_a == mut_b && same_type_modulo_infer(*ty_a, *ty_b)
+        }
         _ => a == b,
     }
 }
@@ -602,7 +605,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         match *cause.code() {
             ObligationCauseCode::Pattern { origin_expr: true, span: Some(span), root_ty } => {
                 let ty = self.resolve_vars_if_possible(root_ty);
-                if ty.is_suggestable() {
+                if !matches!(ty.kind(), ty::Infer(ty::InferTy::TyVar(_) | ty::InferTy::FreshTy(_)))
+                {
                     // don't show type `_`
                     err.span_label(span, format!("this expression has type `{}`", ty));
                 }

compiler/rustc_infer/src/infer/mod.rs

@@ -1434,6 +1434,17 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         value.fold_with(&mut r)
     }
 
+    pub fn resolve_numeric_literals_with_default<T>(&self, value: T) -> T
+    where
+        T: TypeFoldable<'tcx>,
+    {
+        if !value.needs_infer() {
+            return value; // Avoid duplicated subst-folding.
+        }
+        let mut r = InferenceLiteralEraser { tcx: self.tcx };
+        value.fold_with(&mut r)
+    }
+
     /// Returns the first unresolved variable contained in `T`. In the
     /// process of visiting `T`, this will resolve (where possible)
     /// type variables in `T`, but it never constructs the final,
@@ -1785,6 +1796,26 @@ impl<'tcx> TyOrConstInferVar<'tcx> {
     }
 }
 
+/// Replace `{integer}` with `i32` and `{float}` with `f64`.
+/// Used only for diagnostics.
+struct InferenceLiteralEraser<'tcx> {
+    tcx: TyCtxt<'tcx>,
+}
+
+impl<'tcx> TypeFolder<'tcx> for InferenceLiteralEraser<'tcx> {
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+
+    fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
+        match ty.kind() {
+            ty::Infer(ty::IntVar(_) | ty::FreshIntTy(_)) => self.tcx.types.i32,
+            ty::Infer(ty::FloatVar(_) | ty::FreshFloatTy(_)) => self.tcx.types.f64,
+            _ => ty.super_fold_with(self),
+        }
+    }
+}
+
 struct ShallowResolver<'a, 'tcx> {
     infcx: &'a InferCtxt<'a, 'tcx>,
 }

compiler/rustc_target/src/spec/armv6k_nintendo_3ds.rs

@@ -37,6 +37,7 @@ pub fn target() -> Target {
             pre_link_args,
             exe_suffix: ".elf".to_string(),
             no_default_libraries: false,
+            has_thread_local: true,
             ..Default::default()
         },
     }

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -1954,7 +1954,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
 
         if self.is_tainted_by_errors()
             && crate_names.len() == 1
-            && crate_names[0] == "`core`"
+            && ["`core`", "`alloc`", "`std`"].contains(&crate_names[0].as_str())
             && spans.len() == 0
         {
             // Avoid complaining about other inference issues for expressions like

compiler/rustc_typeck/src/astconv/generics.rs

@@ -11,6 +11,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::DefId;
 use rustc_hir::GenericArg;
+use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::ty::{
     self, subst, subst::SubstsRef, GenericParamDef, GenericParamDefKind, Ty, TyCtxt,
 };
@@ -83,7 +84,9 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     if let Some(param_local_id) = param.def_id.as_local() {
                         let param_hir_id = tcx.hir().local_def_id_to_hir_id(param_local_id);
                         let param_name = tcx.hir().ty_param_name(param_hir_id);
-                        let param_type = tcx.type_of(param.def_id);
+                        let param_type = tcx.infer_ctxt().enter(|infcx| {
+                            infcx.resolve_numeric_literals_with_default(tcx.type_of(param.def_id))
+                        });
                         if param_type.is_suggestable() {
                             err.span_suggestion(
                                 tcx.def_span(src_def_id),

compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs

@@ -521,20 +521,29 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         can_suggest: bool,
         fn_id: hir::HirId,
     ) -> bool {
+        let found =
+            self.resolve_numeric_literals_with_default(self.resolve_vars_if_possible(found));
         // Only suggest changing the return type for methods that
         // haven't set a return type at all (and aren't `fn main()` or an impl).
         match (&fn_decl.output, found.is_suggestable(), can_suggest, expected.is_unit()) {
             (&hir::FnRetTy::DefaultReturn(span), true, true, true) => {
                 err.span_suggestion(
                     span,
                     "try adding a return type",
-                    format!("-> {} ", self.resolve_vars_with_obligations(found)),
+                    format!("-> {} ", found),
                     Applicability::MachineApplicable,
                 );
                 true
             }
             (&hir::FnRetTy::DefaultReturn(span), false, true, true) => {
-                err.span_label(span, "possibly return type missing here?");
+                // FIXME: if `found` could be `impl Iterator` or `impl Fn*`, we should suggest
+                // that.
+                err.span_suggestion(
+                    span,
+                    "a return type might be missing here",
+                    "-> _ ".to_string(),
+                    Applicability::HasPlaceholders,
+                );
                 true
             }
             (&hir::FnRetTy::DefaultReturn(span), _, false, true) => {

src/test/ui/async-await/issue-61076.rs

@@ -87,6 +87,7 @@ async fn baz() -> Result<(), ()> {
 
 async fn match_() {
     match tuple() { //~ HELP consider `await`ing on the `Future`
+        //~^ NOTE this expression has type `impl Future<Output = Tuple>`
         Tuple(_) => {} //~ ERROR mismatched types
         //~^ NOTE expected opaque type, found struct `Tuple`
         //~| NOTE expected opaque type `impl Future<Output = Tuple>`

src/test/ui/async-await/issue-61076.stderr

@@ -56,8 +56,11 @@ LL |     struct_().await.method();
    |               ++++++
 
 error[E0308]: mismatched types
-  --> $DIR/issue-61076.rs:90:9
+  --> $DIR/issue-61076.rs:91:9
    |
+LL |     match tuple() {
+   |           ------- this expression has type `impl Future<Output = Tuple>`
+LL |
 LL |         Tuple(_) => {}
    |         ^^^^^^^^ expected opaque type, found struct `Tuple`
    |

src/test/ui/async-await/suggest-missing-await.stderr

@@ -91,6 +91,8 @@ LL ~         1 => dummy().await,
 error[E0308]: mismatched types
   --> $DIR/suggest-missing-await.rs:53:9
    |
+LL |     let _x = match dummy() {
+   |                    ------- this expression has type `impl Future<Output = ()>`
 LL |         () => {}
    |         ^^ expected opaque type, found `()`
    |
@@ -109,6 +111,9 @@ LL |     let _x = match dummy().await {
 error[E0308]: mismatched types
   --> $DIR/suggest-missing-await.rs:67:9
    |
+LL |     match dummy_result() {
+   |           -------------- this expression has type `impl Future<Output = Result<(), ()>>`
+...
 LL |         Ok(_) => {}
    |         ^^^^^ expected opaque type, found enum `Result`
    |
@@ -127,6 +132,9 @@ LL |     match dummy_result().await {
 error[E0308]: mismatched types
   --> $DIR/suggest-missing-await.rs:69:9
    |
+LL |     match dummy_result() {
+   |           -------------- this expression has type `impl Future<Output = Result<(), ()>>`
+...
 LL |         Err(_) => {}
    |         ^^^^^^ expected opaque type, found enum `Result`
    |

src/test/ui/blind/blind-item-block-middle.stderr

@@ -5,7 +5,7 @@ LL | mod foo { pub struct bar; }
    |           --------------- unit struct defined here
 ...
 LL |     let bar = 5;
-   |         ^^^
+   |         ^^^   - this expression has type `{integer}`
    |         |
    |         expected integer, found struct `bar`
    |         `bar` is interpreted as a unit struct, not a new binding

src/test/ui/block-result/issue-20862.stderr

@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-20862.rs:2:5
    |
 LL | fn foo(x: i32) {
-   |                - possibly return type missing here?
+   |                - help: a return type might be missing here: `-> _`
 LL |     |y| x + y
    |     ^^^^^^^^^ expected `()`, found closure
    |

src/test/ui/destructuring-assignment/default-match-bindings-forbidden.stderr

@@ -2,7 +2,9 @@ error[E0308]: mismatched types
   --> $DIR/default-match-bindings-forbidden.rs:4:5
    |
 LL |     (x, y) = &(1, 2);
-   |     ^^^^^^ expected reference, found tuple
+   |     ^^^^^^   ------- this expression has type `&({integer}, {integer})`
+   |     |
+   |     expected reference, found tuple
    |
    = note: expected type `&({integer}, {integer})`
              found tuple `(_, _)`