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Store field indices in DeconstructedPat to avoid virtual wildcards

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Nadrieril
2024-02-29 23:34:57 +01:00
parent c1e68860d0
commit 6ae9fa31f0
4 changed files with 102 additions and 84 deletions
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17
compiler/rustc_pattern_analysis/src/usefulness.rs
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@@ -1006,15 +1006,17 @@ impl<'p, Cx: TypeCx> PatStack<'p, Cx> {
ctor_arity: usize,
ctor_is_relevant: bool,
) -> Result<PatStack<'p, Cx>, Cx::Error> {
// We pop the head pattern and push the new fields extracted from the arguments of
// `self.head()`.
let mut new_pats = self.head().specialize(ctor, ctor_arity);
if new_pats.len() != ctor_arity {
let head_pat = self.head();
if head_pat.as_pat().is_some_and(|pat| pat.arity() > ctor_arity) {
// Arity can be smaller in case of variable-length slices, but mustn't be larger.
return Err(cx.bug(format_args!(
"uncaught type error: pattern {:?} has inconsistent arity (expected arity {ctor_arity})",
self.head().as_pat().unwrap()
"uncaught type error: pattern {:?} has inconsistent arity (expected arity <= {ctor_arity})",
head_pat.as_pat().unwrap()
)));
}
// We pop the head pattern and push the new fields extracted from the arguments of
// `self.head()`.
let mut new_pats = head_pat.specialize(ctor, ctor_arity);
new_pats.extend_from_slice(&self.pats[1..]);
// `ctor` is relevant for this row if it is the actual constructor of this row, or if the
// row has a wildcard and `ctor` is relevant for wildcards.
@@ -1706,7 +1708,8 @@ fn collect_pattern_usefulness<'p, Cx: TypeCx>(
) -> bool {
if useful_subpatterns.contains(&pat.uid) {
true
} else if pat.is_or_pat() && pat.iter_fields().any(|f| pat_is_useful(useful_subpatterns, f))
} else if pat.is_or_pat()
&& pat.iter_fields().any(|f| pat_is_useful(useful_subpatterns, &f.pat))
{
// We always expand or patterns in the matrix, so we will never see the actual
// or-pattern (the one with constructor `Or`) in the column. As such, it will not be