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Remove duplicate error about raw underscore lifetime #143280

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Remove duplicate error about raw underscore lifetime #143280

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ee4395b
Add test raw-underscore-lifetime.rs
xizheyin Jul 1, 2025
edd5a3e
Remove duplicate error about raw underscore lifetime
xizheyin Jul 1, 2025
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11 changes: 10 additions & 1 deletion compiler/rustc_resolve/src/late.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2902,7 +2902,16 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
}
}

if param.ident.name == kw::UnderscoreLifetime {
// To avoid emitting two duplicate errors, we need to check if the span is a raw underscore lifetime, see issue #143152
let is_raw_underscore = self
.r
.tcx
.sess
.psess
.raw_identifier_spans
.iter()
.any(|span| span == param.span());
if param.ident.name == kw::UnderscoreLifetime && !is_raw_underscore {
Comment on lines +2905 to +2914
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I'm wondering if I should split it into 2 parts, as this doesn't seem very aesthetically pleasing taking up so many lines. However it seems to give the wrong impression that the variable in the middle will be used multiple times.

self.r
.dcx()
.emit_err(errors::UnderscoreLifetimeIsReserved { span: param.ident.span });
Comment on lines +2905 to 2917
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Use emit_unless, and also we don't need to factor this into a variable.

Suggested change
// To avoid emitting two duplicate errors, we need to check if the span is a raw underscore lifetime, see issue #143152
let is_raw_underscore = self
.r
.tcx
.sess
.psess
.raw_identifier_spans
.iter()
.any(|span| span == param.span());
if param.ident.name == kw::UnderscoreLifetime && !is_raw_underscore {
self.r
.dcx()
.emit_err(errors::UnderscoreLifetimeIsReserved { span: param.ident.span });
self.r
.dcx()
.create_err(errors::UnderscoreLifetimeIsReserved {
span: param.ident.span,
})
// To avoid emitting two duplicate errors, we need to check if the span is a raw underscore lifetime, see issue #143152
.emit_unless(
kw::UnderscoreLifetime
&& self
.r
.tcx
.sess
.psess
.raw_identifier_spans
.iter()
.any(|span| span == param.span()),
);

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Also I think the comment could be tweaked; instead of "two duplicate errors", b/c the error is not duplicate, we should say something different.

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9 changes: 9 additions & 0 deletions tests/ui/underscore-lifetime/raw-underscore-lifetime.rs
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@@ -0,0 +1,9 @@
// This test is to ensure that the raw underscore lifetime won't emit two duplicate errors.
// See issue #143152

//@ edition: 2021

fn f<'r#_>(){}
//~^ ERROR `_` cannot be a raw lifetime

fn main() {}
8 changes: 8 additions & 0 deletions tests/ui/underscore-lifetime/raw-underscore-lifetime.stderr
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Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
error: `_` cannot be a raw lifetime
--> $DIR/raw-underscore-lifetime.rs:6:6
|
LL | fn f<'r#_>(){}
| ^^^^

error: aborting due to 1 previous error

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