Rollup merge of rust-lang#145227 - estebank:tweak-inference-span, r=joshtriplett

Tweak spans providing type context on errors when involving macros

Do not point at macro invocation multiple times when we try to add span labels mentioning what type each expression has, which is unnecessary when the error is at a macro invocation.

Author: Zalathar

compiler/rustc_hir_typeck/src/demand.rs

@@ -698,7 +698,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     ) {
         match (self.tcx.parent_hir_node(expr.hir_id), error) {
             (hir::Node::LetStmt(hir::LetStmt { ty: Some(ty), init: Some(init), .. }), _)
-                if init.hir_id == expr.hir_id =>
+                if init.hir_id == expr.hir_id && !ty.span.source_equal(init.span) =>
             {
                 // Point at `let` assignment type.
                 err.span_label(ty.span, "expected due to this");

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

@@ -459,7 +459,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             span,
                             format!("this is an iterator with items of type `{}`", args.type_at(0)),
                         );
-                    } else {
+                    } else if !span.overlaps(cause.span) {
                         let expected_ty = self.tcx.short_string(expected_ty, err.long_ty_path());
                         err.span_label(span, format!("this expression has type `{expected_ty}`"));
                     }

tests/ui/proc-macro/auxiliary/match-expander.rs

@@ -0,0 +1,15 @@
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+
+#[proc_macro]
+pub fn matcher(input: TokenStream) -> TokenStream {
+"
+struct S(());
+let s = S(());
+match s {
+    true => {}
+    _ => {}
+}
+".parse().unwrap()
+}

tests/ui/proc-macro/match-expander.rs

@@ -0,0 +1,12 @@
+//@ proc-macro: match-expander.rs
+// Ensure that we don't point at macro invocation when providing inference contexts.
+
+#[macro_use]
+extern crate match_expander;
+
+fn main() {
+    match_expander::matcher!();
+    //~^ ERROR: mismatched types
+    //~| NOTE: expected `S`, found `bool`
+    //~| NOTE: in this expansion of match_expander::matcher!
+}

tests/ui/proc-macro/match-expander.stderr

@@ -0,0 +1,11 @@
+error[E0308]: mismatched types
+  --> $DIR/match-expander.rs:8:5
+   |
+LL |     match_expander::matcher!();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `S`, found `bool`
+   |
+   = note: this error originates in the macro `match_expander::matcher` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.

tests/ui/proc-macro/quote/does-not-have-iter-interpolated-dup.stderr

@@ -5,7 +5,6 @@ LL |     quote!($($nonrep $nonrep)*);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |     |
    |     expected `HasIterator`, found `ThereIsNoIteratorInRepetition`
-   |     expected due to this
    |     here the type of `has_iter` is inferred to be `ThereIsNoIteratorInRepetition`
 
 error: aborting due to 1 previous error

tests/ui/proc-macro/quote/does-not-have-iter-interpolated.stderr

@@ -5,7 +5,6 @@ LL |     quote!($($nonrep)*);
    |     ^^^^^^^^^^^^^^^^^^^
    |     |
    |     expected `HasIterator`, found `ThereIsNoIteratorInRepetition`
-   |     expected due to this
    |     here the type of `has_iter` is inferred to be `ThereIsNoIteratorInRepetition`
 
 error: aborting due to 1 previous error

tests/ui/proc-macro/quote/does-not-have-iter-separated.stderr

@@ -2,10 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/does-not-have-iter-separated.rs:8:5
    |
 LL |     quote!($(a b),*);
-   |     ^^^^^^^^^^^^^^^^
-   |     |
-   |     expected `HasIterator`, found `ThereIsNoIteratorInRepetition`
-   |     expected due to this
+   |     ^^^^^^^^^^^^^^^^ expected `HasIterator`, found `ThereIsNoIteratorInRepetition`
 
 error: aborting due to 1 previous error
 

tests/ui/proc-macro/quote/does-not-have-iter.stderr

@@ -2,10 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/does-not-have-iter.rs:8:5
    |
 LL |     quote!($(a b)*);
-   |     ^^^^^^^^^^^^^^^
-   |     |
-   |     expected `HasIterator`, found `ThereIsNoIteratorInRepetition`
-   |     expected due to this
+   |     ^^^^^^^^^^^^^^^ expected `HasIterator`, found `ThereIsNoIteratorInRepetition`
 
 error: aborting due to 1 previous error