diff options
Diffstat (limited to 'compiler/rustc_pattern_analysis/src/usefulness.rs')
| -rw-r--r-- | compiler/rustc_pattern_analysis/src/usefulness.rs | 17 |
1 files changed, 7 insertions, 10 deletions
diff --git a/compiler/rustc_pattern_analysis/src/usefulness.rs b/compiler/rustc_pattern_analysis/src/usefulness.rs index d2e621a6b98..68da13861aa 100644 --- a/compiler/rustc_pattern_analysis/src/usefulness.rs +++ b/compiler/rustc_pattern_analysis/src/usefulness.rs @@ -847,8 +847,11 @@ impl<'p, Cx: TypeCx> PatStack<'p, Cx> { self.pats.len() } + fn head_opt(&self) -> Option<&'p DeconstructedPat<'p, Cx>> { + self.pats.first().copied() + } fn head(&self) -> &'p DeconstructedPat<'p, Cx> { - self.pats[0] + self.head_opt().unwrap() } fn iter(&self) -> impl Iterator<Item = &'p DeconstructedPat<'p, Cx>> + Captures<'_> { @@ -1028,14 +1031,8 @@ impl<'p, Cx: TypeCx> Matrix<'p, Cx> { matrix } - fn head_ty(&self, mcx: MatchCtxt<'_, 'p, Cx>) -> Option<Cx::Ty> { - if self.column_count() == 0 { - return None; - } - - let ty = self.wildcard_row.head().ty(); - // FIXME(Nadrieril): `Cx` should only give us revealed types. - Some(mcx.tycx.reveal_opaque_ty(ty)) + fn head_ty(&self) -> Option<Cx::Ty> { + self.wildcard_row.head_opt().map(|pat| pat.ty()) } fn column_count(&self) -> usize { self.wildcard_row.len() @@ -1345,7 +1342,7 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>( return WitnessMatrix::empty(); } - let Some(ty) = matrix.head_ty(mcx) else { + let Some(ty) = matrix.head_ty() else { // The base case: there are no columns in the matrix. We are morally pattern-matching on (). // A row is useful iff it has no (unguarded) rows above it. for row in matrix.rows_mut() { |