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Fix #103320, add explanatory message for [#must_use]

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This commit is contained in:
yukang 2022-10-29 21:14:02 +08:00
parent a94b9fd0ac
commit cb55d10eb2
7 changed files with 142 additions and 9 deletions
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18
compiler/rustc_lint/src/lints.rs
View file

@ -1402,6 +1402,21 @@ pub struct UnusedDef<'a, 'b> {
pub cx: &'a LateContext<'b>,
pub def_id: DefId,
pub note: Option<Symbol>,
pub suggestion: Option<UnusedDefSuggestion>,
}
#[derive(Subdiagnostic)]
pub enum UnusedDefSuggestion {
#[suggestion(
suggestion,
style = "verbose",
code = "let _ = ",
applicability = "machine-applicable"
)]
Default {
#[primary_span]
span: Span,
},
}
// Needed because of def_path_str
@ -1417,6 +1432,9 @@ impl<'a> DecorateLint<'a, ()> for UnusedDef<'_, '_> {
if let Some(note) = self.note {
diag.note(note.as_str());
}
if let Some(sugg) = self.suggestion {
diag.subdiagnostic(sugg);
}
diag
}

18
compiler/rustc_lint/src/unused.rs
View file

@ -1,7 +1,7 @@
use crate::lints::{
PathStatementDrop, PathStatementDropSub, PathStatementNoEffect, UnusedAllocationDiag,
UnusedAllocationMutDiag, UnusedClosure, UnusedDef, UnusedDelim, UnusedDelimSuggestion,
UnusedGenerator, UnusedImportBracesDiag, UnusedOp, UnusedResult,
UnusedAllocationMutDiag, UnusedClosure, UnusedDef, UnusedDefSuggestion, UnusedDelim,
UnusedDelimSuggestion, UnusedGenerator, UnusedImportBracesDiag, UnusedOp, UnusedResult,
};
use crate::Lint;
use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
@ -418,6 +418,19 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
);
}
MustUsePath::Def(span, def_id, reason) => {
let suggestion = if matches!(
cx.tcx.get_diagnostic_name(*def_id),
Some(sym::add)
| Some(sym::sub)
| Some(sym::mul)
| Some(sym::div)
| Some(sym::rem)
| Some(sym::neg),
) {
Some(UnusedDefSuggestion::Default { span: span.shrink_to_lo() })
} else {
None
};
cx.emit_spanned_lint(
UNUSED_MUST_USE,
*span,
@ -427,6 +440,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
cx,
def_id: *def_id,
note: *reason,
suggestion,
},
);
}