Avoid redundant type error label in assert!

Author: estebank

compiler/rustc_builtin_macros/src/assert.rs

@@ -171,15 +171,15 @@ fn expand_cond(cx: &ExtCtxt<'_>, parser: Parser<'_>, cond_expr: P<Expr>) -> P<Ex
     // entire macro call. If a non-`bool` is passed that doesn't implement `trait Not`, we won't
     // talk about traits, we'll just state the appropriate type error.
     // `let assert_macro: bool = $expr;`
-    let ident = Ident::new(sym::assert_macro, span);
+    let ident = Ident::new(sym::assert_macro, DUMMY_SP);
     let local = P(ast::Local {
         ty: Some(P(ast::Ty {
-            kind: ast::TyKind::Path(None, ast::Path::from_ident(Ident::new(sym::bool, span))),
+            kind: ast::TyKind::Path(None, ast::Path::from_ident(Ident::new(sym::bool, DUMMY_SP))),
             id: ast::DUMMY_NODE_ID,
-            span,
+            span: DUMMY_SP,
             tokens: None,
         })),
-        pat: parser.mk_pat_ident(span, ast::BindingAnnotation::NONE, ident),
+        pat: parser.mk_pat_ident(DUMMY_SP, ast::BindingAnnotation::NONE, ident),
         kind: ast::LocalKind::Init(cond_expr),
         id: ast::DUMMY_NODE_ID,
         span,

compiler/rustc_hir_typeck/src/demand.rs

@@ -679,7 +679,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     ) {
         match (self.tcx.parent_hir_node(expr.hir_id), error) {
             (hir::Node::Local(hir::Local { ty: Some(ty), init: Some(init), .. }), _)
-                if init.hir_id == expr.hir_id =>
+                if init.hir_id == expr.hir_id && !ty.span.is_dummy() =>
             {
                 // Point at `let` assignment type.
                 err.span_label(ty.span, "expected due to this");

tests/ui/codemap_tests/issue-28308.stderr

@@ -2,10 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-28308.rs:2:13
    |
 LL |     assert!("foo");
-   |             ^^^^^
-   |             |
-   |             expected `bool`, found `&str`
-   |             expected due to this
+   |             ^^^^^ expected `bool`, found `&str`
 
 error: aborting due to 1 previous error
 

tests/ui/issues/issue-14091-2.stderr

@@ -2,10 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-14091-2.rs:15:13
    |
 LL |     assert!(x, x);
-   |             ^
-   |             |
-   |             expected `bool`, found `BytePos`
-   |             expected due to this
+   |             ^ expected `bool`, found `BytePos`
 
 error: aborting due to 1 previous error
 

tests/ui/issues/issue-14091.stderr

@@ -2,10 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-14091.rs:2:13
    |
 LL |     assert!(1,1);
-   |             ^
-   |             |
-   |             expected `bool`, found integer
-   |             expected due to this
+   |             ^ expected `bool`, found integer
 
 error: aborting due to 1 previous error