Auto merge of #84112 - Dylan-DPC:rollup-tapsrzz, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - #83669 (Issue 81508 fix)
 - #84014 (Improve trait/impl method discrepancy errors)
 - #84059 (Bump libc dependency of std to 0.2.93)
 - #84067 (clean up example on read_to_string)
 - #84079 (Improve test for `rustdoc::bare_urls` lint)
 - #84094 (Remove FixedSizeArray)
 - #84101 (rustdoc: Move crate loader to collect_intra_doc_links::early )

Failed merges:

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

Cargo.lock

@@ -1909,9 +1909,9 @@ checksum = "830d08ce1d1d941e6b30645f1a0eb5643013d835ce3779a5fc208261dbe10f55"
 
 [[package]]
 name = "libc"
-version = "0.2.88"
+version = "0.2.93"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "03b07a082330a35e43f63177cc01689da34fbffa0105e1246cf0311472cac73a"
+checksum = "9385f66bf6105b241aa65a61cb923ef20efc665cb9f9bb50ac2f0c4b7f378d41"
 dependencies = [
  "rustc-std-workspace-core",
 ]

compiler/rustc_middle/src/ty/error.rs

@@ -36,6 +36,7 @@ pub enum TypeError<'tcx> {
     UnsafetyMismatch(ExpectedFound<hir::Unsafety>),
     AbiMismatch(ExpectedFound<abi::Abi>),
     Mutability,
+    ArgumentMutability(usize),
     TupleSize(ExpectedFound<usize>),
     FixedArraySize(ExpectedFound<u64>),
     ArgCount,
@@ -46,6 +47,7 @@ pub enum TypeError<'tcx> {
     RegionsPlaceholderMismatch,
 
     Sorts(ExpectedFound<Ty<'tcx>>),
+    ArgumentSorts(ExpectedFound<Ty<'tcx>>, usize),
     IntMismatch(ExpectedFound<ty::IntVarValue>),
     FloatMismatch(ExpectedFound<ty::FloatTy>),
     Traits(ExpectedFound<DefId>),
@@ -110,7 +112,7 @@ impl<'tcx> fmt::Display for TypeError<'tcx> {
             AbiMismatch(values) => {
                 write!(f, "expected {} fn, found {} fn", values.expected, values.found)
             }
-            Mutability => write!(f, "types differ in mutability"),
+            ArgumentMutability(_) | Mutability => write!(f, "types differ in mutability"),
             TupleSize(values) => write!(
                 f,
                 "expected a tuple with {} element{}, \
@@ -142,7 +144,7 @@ impl<'tcx> fmt::Display for TypeError<'tcx> {
                 br_string(br)
             ),
             RegionsPlaceholderMismatch => write!(f, "one type is more general than the other"),
-            Sorts(values) => ty::tls::with(|tcx| {
+            ArgumentSorts(values, _) | Sorts(values) => ty::tls::with(|tcx| {
                 report_maybe_different(
                     f,
                     &values.expected.sort_string(tcx),
@@ -199,10 +201,11 @@ impl<'tcx> TypeError<'tcx> {
         use self::TypeError::*;
         match self {
             CyclicTy(_) | CyclicConst(_) | UnsafetyMismatch(_) | Mismatch | AbiMismatch(_)
-            | FixedArraySize(_) | Sorts(_) | IntMismatch(_) | FloatMismatch(_)
-            | VariadicMismatch(_) | TargetFeatureCast(_) => false,
+            | FixedArraySize(_) | ArgumentSorts(..) | Sorts(_) | IntMismatch(_)
+            | FloatMismatch(_) | VariadicMismatch(_) | TargetFeatureCast(_) => false,
 
             Mutability
+            | ArgumentMutability(_)
             | TupleSize(_)
             | ArgCount
             | RegionsDoesNotOutlive(..)
@@ -339,7 +342,7 @@ impl<'tcx> TyCtxt<'tcx> {
         use self::TypeError::*;
         debug!("note_and_explain_type_err err={:?} cause={:?}", err, cause);
         match err {
-            Sorts(values) => {
+            ArgumentSorts(values, _) | Sorts(values) => {
                 match (values.expected.kind(), values.found.kind()) {
                     (ty::Closure(..), ty::Closure(..)) => {
                         db.note("no two closures, even if identical, have the same type");

compiler/rustc_middle/src/ty/relate.rs

@@ -179,6 +179,12 @@ impl<'tcx> Relate<'tcx> for ty::FnSig<'tcx> {
                 } else {
                     relation.relate_with_variance(ty::Contravariant, a, b)
                 }
+            })
+            .enumerate()
+            .map(|(i, r)| match r {
+                Err(TypeError::Sorts(exp_found)) => Err(TypeError::ArgumentSorts(exp_found, i)),
+                Err(TypeError::Mutability) => Err(TypeError::ArgumentMutability(i)),
+                r => r,
             });
         Ok(ty::FnSig {
             inputs_and_output: tcx.mk_type_list(inputs_and_output)?,

compiler/rustc_middle/src/ty/structural_impls.rs

@@ -587,6 +587,7 @@ impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
             UnsafetyMismatch(x) => UnsafetyMismatch(x),
             AbiMismatch(x) => AbiMismatch(x),
             Mutability => Mutability,
+            ArgumentMutability(i) => ArgumentMutability(i),
             TupleSize(x) => TupleSize(x),
             FixedArraySize(x) => FixedArraySize(x),
             ArgCount => ArgCount,
@@ -607,6 +608,7 @@ impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
             CyclicTy(t) => return tcx.lift(t).map(|t| CyclicTy(t)),
             CyclicConst(ct) => return tcx.lift(ct).map(|ct| CyclicConst(ct)),
             ProjectionMismatched(x) => ProjectionMismatched(x),
+            ArgumentSorts(x, i) => return tcx.lift(x).map(|x| ArgumentSorts(x, i)),
             Sorts(x) => return tcx.lift(x).map(Sorts),
             ExistentialMismatch(x) => return tcx.lift(x).map(ExistentialMismatch),
             ConstMismatch(x) => return tcx.lift(x).map(ConstMismatch),

compiler/rustc_resolve/src/late.rs

@@ -1031,7 +1031,6 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
             }
 
             ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
-                debug!("resolve_item ItemKind::Const");
                 self.with_item_rib(HasGenericParams::No, |this| {
                     this.visit_ty(ty);
                     if let Some(expr) = expr {
@@ -1597,6 +1596,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                         .try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
                         .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
                     self.r.record_partial_res(pat.id, PartialRes::new(res));
+                    self.r.record_pat_span(pat.id, pat.span);
                 }
                 PatKind::TupleStruct(ref path, ref sub_patterns) => {
                     self.smart_resolve_path(

compiler/rustc_resolve/src/lib.rs

@@ -891,6 +891,10 @@ pub struct Resolver<'a> {
     /// "self-confirming" import resolutions during import validation.
     unusable_binding: Option<&'a NameBinding<'a>>,
 
+    // Spans for local variables found during pattern resolution.
+    // Used for suggestions during error reporting.
+    pat_span_map: NodeMap<Span>,
+
     /// Resolutions for nodes that have a single resolution.
     partial_res_map: NodeMap<PartialRes>,
     /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
@@ -1270,6 +1274,7 @@ impl<'a> Resolver<'a> {
             last_import_segment: false,
             unusable_binding: None,
 
+            pat_span_map: Default::default(),
             partial_res_map: Default::default(),
             import_res_map: Default::default(),
             label_res_map: Default::default(),
@@ -1917,7 +1922,6 @@ impl<'a> Resolver<'a> {
                 return Some(LexicalScopeBinding::Item(binding));
             }
         }
-
         self.early_resolve_ident_in_lexical_scope(
             orig_ident,
             ScopeSet::Late(ns, module, record_used_id),
@@ -2394,7 +2398,59 @@ impl<'a> Resolver<'a> {
                             .next()
                             .map_or(false, |c| c.is_ascii_uppercase())
                         {
-                            (format!("use of undeclared type `{}`", ident), None)
+                            // Check whether the name refers to an item in the value namespace.
+                            let suggestion = if ribs.is_some() {
+                                let match_span = match self.resolve_ident_in_lexical_scope(
+                                    ident,
+                                    ValueNS,
+                                    parent_scope,
+                                    None,
+                                    path_span,
+                                    &ribs.unwrap()[ValueNS],
+                                ) {
+                                    // Name matches a local variable. For example:
+                                    // ```
+                                    // fn f() {
+                                    //     let Foo: &str = "";
+                                    //     println!("{}", Foo::Bar); // Name refers to local
+                                    //                               // variable `Foo`.
+                                    // }
+                                    // ```
+                                    Some(LexicalScopeBinding::Res(Res::Local(id))) => {
+                                        Some(*self.pat_span_map.get(&id).unwrap())
+                                    }
+
+                                    // Name matches item from a local name binding
+                                    // created by `use` declaration. For example:
+                                    // ```
+                                    // pub Foo: &str = "";
+                                    //
+                                    // mod submod {
+                                    //     use super::Foo;
+                                    //     println!("{}", Foo::Bar); // Name refers to local
+                                    //                               // binding `Foo`.
+                                    // }
+                                    // ```
+                                    Some(LexicalScopeBinding::Item(name_binding)) => {
+                                        Some(name_binding.span)
+                                    }
+                                    _ => None,
+                                };
+
+                                if let Some(span) = match_span {
+                                    Some((
+                                        vec![(span, String::from(""))],
+                                        format!("`{}` is defined here, but is not a type", ident),
+                                        Applicability::MaybeIncorrect,
+                                    ))
+                                } else {
+                                    None
+                                }
+                            } else {
+                                None
+                            };
+
+                            (format!("use of undeclared type `{}`", ident), suggestion)
                         } else {
                             (format!("use of undeclared crate or module `{}`", ident), None)
                         }
@@ -2805,6 +2861,11 @@ impl<'a> Resolver<'a> {
         }
     }
 
+    fn record_pat_span(&mut self, node: NodeId, span: Span) {
+        debug!("(recording pat) recording {:?} for {:?}", node, span);
+        self.pat_span_map.insert(node, span);
+    }
+
     fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
         vis.is_accessible_from(module.nearest_parent_mod, self)
     }