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Rollup merge of #136869 - chenyukang:yukang-fix-133713-let-binding, r=estebank

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Fix diagnostic when using = instead of : in let binding

Fixes #133713

r? ``@estebank``
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Jubilee 2025-02-13 17:46:08 -08:00 • committed by GitHub
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4 changed files with 73 additions and 1 deletions
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23
compiler/rustc_resolve/src/late/diagnostics.rs
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@ -2347,9 +2347,14 @@ impl<'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
// try to give a suggestion for this pattern: `name = blah`, which is common in other languages
// suggest `let name = blah` to introduce a new binding
fn let_binding_suggestion(&mut self, err: &mut Diag<'_>, ident_span: Span) -> bool {
if ident_span.from_expansion() {
return false;
}
// only suggest when the code is a assignment without prefix code
if let Some(Expr { kind: ExprKind::Assign(lhs, ..), .. }) = self.diag_metadata.in_assignment
&& let ast::ExprKind::Path(None, ref path) = lhs.kind
&& !ident_span.from_expansion()
&& self.r.tcx.sess.source_map().is_line_before_span_empty(ident_span)
{
let (span, text) = match path.segments.first() {
Some(seg) if let Some(name) = seg.ident.as_str().strip_prefix("let") => {
@ -2368,6 +2373,22 @@ impl<'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
);
return true;
}
// a special case for #133713
// '=' maybe a typo of `:`, which is a type annotation instead of assignment
if err.code == Some(E0423)
&& let Some((let_span, None, Some(val_span))) = self.diag_metadata.current_let_binding
&& val_span.contains(ident_span)
&& val_span.lo() == ident_span.lo()
{
err.span_suggestion_verbose(
let_span.shrink_to_hi().to(val_span.shrink_to_lo()),
"you might have meant to use `:` for type annotation",
": ",
Applicability::MaybeIncorrect,
);
return true;
}
false
}