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Show the unused type for unused_results lint #91818

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Merged
merged 1 commit into from
Dec 18, 2021
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Show the unused type for unused_results lint #91818

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4 changes: 3 additions & 1 deletion compiler/rustc_lint/src/unused.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -169,7 +169,9 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
}

if !(type_permits_lack_of_use || fn_warned || op_warned) {
cx.struct_span_lint(UNUSED_RESULTS, s.span, |lint| lint.build("unused result").emit());
cx.struct_span_lint(UNUSED_RESULTS, s.span, |lint| {
lint.build(&format!("unused result of type `{}`", ty)).emit()
});
}

// Returns whether an error has been emitted (and thus another does not need to be later).
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2 changes: 1 addition & 1 deletion src/test/ui/lint/unused/unused-result.rs
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Expand Up @@ -31,7 +31,7 @@ fn test2() {
}

fn main() {
foo::<isize>(); //~ ERROR: unused result
foo::<isize>(); //~ ERROR: unused result of type `isize`
foo::<MustUse>(); //~ ERROR: unused `MustUse` that must be used
foo::<MustUseMsg>(); //~ ERROR: unused `MustUseMsg` that must be used
//~^ NOTE: some message
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2 changes: 1 addition & 1 deletion src/test/ui/lint/unused/unused-result.stderr
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Expand Up @@ -18,7 +18,7 @@ LL | foo::<MustUseMsg>();
|
= note: some message

error: unused result
error: unused result of type `isize`
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Alternatively, the type could be displayed in a note, but using the title is consistent with unused_must_use and easier to scan IMO.

--> $DIR/unused-result.rs:34:5
|
LL | foo::<isize>();
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