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Commit 62a7839

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authoredNov 23, 2019
Rollup merge of #66539 - estebank:let-ty, r=Centril
Point at type in `let` assignment on type errors Fix #61067.
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1.88.01.41.0
2 parents 6618af2 + 34f03c0 commit 62a7839

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‎src/librustc_typeck/check/demand.rs

Lines changed: 22 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -102,12 +102,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
102102
// N.B., this code relies on `self.diverges` to be accurate. In
103103
// particular, assignments to `!` will be permitted if the
104104
// diverges flag is currently "always".
105-
pub fn demand_coerce_diag(&self,
106-
expr: &hir::Expr,
107-
checked_ty: Ty<'tcx>,
108-
expected: Ty<'tcx>,
109-
allow_two_phase: AllowTwoPhase)
110-
-> (Ty<'tcx>, Option<DiagnosticBuilder<'tcx>>) {
105+
pub fn demand_coerce_diag(
106+
&self,
107+
expr: &hir::Expr,
108+
checked_ty: Ty<'tcx>,
109+
expected: Ty<'tcx>,
110+
allow_two_phase: AllowTwoPhase,
111+
) -> (Ty<'tcx>, Option<DiagnosticBuilder<'tcx>>) {
111112
let expected = self.resolve_vars_with_obligations(expected);
112113

113114
let e = match self.try_coerce(expr, checked_ty, expected, allow_two_phase) {
@@ -126,6 +127,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
126127
return (expected, None)
127128
}
128129

130+
self.annotate_expected_due_to_let_ty(&mut err, expr);
129131
self.suggest_compatible_variants(&mut err, expr, expected, expr_ty);
130132
self.suggest_ref_or_into(&mut err, expr, expected, expr_ty);
131133
self.suggest_boxing_when_appropriate(&mut err, expr, expected, expr_ty);
@@ -134,6 +136,20 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
134136
(expected, Some(err))
135137
}
136138

139+
fn annotate_expected_due_to_let_ty(&self, err: &mut DiagnosticBuilder<'_>, expr: &hir::Expr) {
140+
let parent = self.tcx.hir().get_parent_node(expr.hir_id);
141+
if let Some(hir::Node::Local(hir::Local {
142+
ty: Some(ty),
143+
init: Some(init),
144+
..
145+
})) = self.tcx.hir().find(parent) {
146+
if init.hir_id == expr.hir_id {
147+
// Point at `let` assignment type.
148+
err.span_label(ty.span, "expected due to this");
149+
}
150+
}
151+
}
152+
137153
/// Returns whether the expected type is `bool` and the expression is `x = y`.
138154
pub fn is_assign_to_bool(&self, expr: &hir::Expr, expected: Ty<'tcx>) -> bool {
139155
if let hir::ExprKind::Assign(..) = expr.kind {

‎src/test/rustdoc-ui/failed-doctest-missing-codes.stdout

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,9 @@ error[E0308]: mismatched types
99
--> $DIR/failed-doctest-missing-codes.rs:9:13
1010
|
1111
LL | let x: () = 5i32;
12-
| ^^^^ expected `()`, found `i32`
12+
| -- ^^^^ expected `()`, found `i32`
13+
| |
14+
| expected due to this
1315

1416
error: aborting due to previous error
1517

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