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Rollup merge of #129394 - Jarcho:irrefutable_let_patterns, r=Nadrieril

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Don't lint `irrefutable_let_patterns` on leading patterns if `else if` let-chains

fixes #128661

Is there any preference where the test goes? There looks to be several places it could fit.
This commit is contained in:
Matthias Krüger 2024-10-30 06:40:34 +01:00 • committed by GitHub
commit 87d348b333
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3 changed files with 57 additions and 8 deletions
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25
compiler/rustc_mir_build/src/thir/pattern/check_match.rs
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@ -79,6 +79,8 @@ enum LetSource {
IfLetGuard,
LetElse,
WhileLet,
Else,
ElseIfLet,
}
struct MatchVisitor<'p, 'tcx> {
@ -129,15 +131,20 @@ impl<'p, 'tcx> Visitor<'p, 'tcx> for MatchVisitor<'p, 'tcx> {
// Give a specific `let_source` for the condition.
let let_source = match ex.span.desugaring_kind() {
Some(DesugaringKind::WhileLoop) => LetSource::WhileLet,
_ => LetSource::IfLet,
_ => match self.let_source {
LetSource::Else => LetSource::ElseIfLet,
_ => LetSource::IfLet,
},
};
self.with_let_source(let_source, |this| this.visit_expr(&self.thir[cond]));
self.with_let_source(LetSource::None, |this| {
this.visit_expr(&this.thir[then]);
if let Some(else_) = else_opt {
this.visit_expr(&this.thir[else_]);
}
});
if let Some(else_) = else_opt {
self.with_let_source(LetSource::Else, |this| {
this.visit_expr(&this.thir[else_])
});
}
return;
}
ExprKind::Match { scrutinee, scrutinee_hir_id: _, box ref arms, match_source } => {
@ -573,9 +580,13 @@ impl<'p, 'tcx> MatchVisitor<'p, 'tcx> {
// and we shouldn't lint.
// For let guards inside a match, prefixes might use bindings of the match pattern,
// so can't always be moved out.
// For `else if let`, an extra indentation level would be required to move the bindings.
// FIXME: Add checking whether the bindings are actually used in the prefix,
// and lint if they are not.
if !matches!(self.let_source, LetSource::WhileLet | LetSource::IfLetGuard) {
if !matches!(
self.let_source,
LetSource::WhileLet | LetSource::IfLetGuard | LetSource::ElseIfLet
) {
// Emit the lint
let prefix = &chain_refutabilities[..until];
let span_start = prefix[0].unwrap().0;
@ -906,8 +917,8 @@ fn report_irrefutable_let_patterns(
}
match source {
LetSource::None | LetSource::PlainLet => bug!(),
LetSource::IfLet => emit_diag!(IrrefutableLetPatternsIfLet),
LetSource::None | LetSource::PlainLet | LetSource::Else => bug!(),
LetSource::IfLet | LetSource::ElseIfLet => emit_diag!(IrrefutableLetPatternsIfLet),
LetSource::IfLetGuard => emit_diag!(IrrefutableLetPatternsIfLetGuard),
LetSource::LetElse => emit_diag!(IrrefutableLetPatternsLetElse),
LetSource::WhileLet => emit_diag!(IrrefutableLetPatternsWhileLet),