diff options
| -rw-r--r-- | compiler/rustc_mir_build/src/thir/pattern/_match.rs | 182 |
1 files changed, 89 insertions, 93 deletions
diff --git a/compiler/rustc_mir_build/src/thir/pattern/_match.rs b/compiler/rustc_mir_build/src/thir/pattern/_match.rs index f299663f679..75c12f379af 100644 --- a/compiler/rustc_mir_build/src/thir/pattern/_match.rs +++ b/compiler/rustc_mir_build/src/thir/pattern/_match.rs @@ -993,93 +993,6 @@ impl<'tcx> Constructor<'tcx> { } } } - - /// Apply a constructor to a list of patterns, yielding a new pattern. `pats` - /// must have as many elements as this constructor's arity. - /// - /// This is roughly the inverse of `specialize_constructor`. - /// - /// Examples: - /// `self`: `Constructor::Single` - /// `ty`: `(u32, u32, u32)` - /// `pats`: `[10, 20, _]` - /// returns `(10, 20, _)` - /// - /// `self`: `Constructor::Variant(Option::Some)` - /// `ty`: `Option<bool>` - /// `pats`: `[false]` - /// returns `Some(false)` - fn apply<'p>(&self, pcx: PatCtxt<'_, 'p, 'tcx>, fields: Fields<'p, 'tcx>) -> Pat<'tcx> { - let mut subpatterns = fields.all_patterns(); - - let pat = match self { - Single | Variant(_) => match pcx.ty.kind() { - ty::Adt(..) | ty::Tuple(..) => { - let subpatterns = subpatterns - .enumerate() - .map(|(i, p)| FieldPat { field: Field::new(i), pattern: p }) - .collect(); - - if let ty::Adt(adt, substs) = pcx.ty.kind() { - if adt.is_enum() { - PatKind::Variant { - adt_def: adt, - substs, - variant_index: self.variant_index_for_adt(adt), - subpatterns, - } - } else { - PatKind::Leaf { subpatterns } - } - } else { - PatKind::Leaf { subpatterns } - } - } - // Note: given the expansion of `&str` patterns done in `expand_pattern`, we should - // be careful to reconstruct the correct constant pattern here. However a string - // literal pattern will never be reported as a non-exhaustiveness witness, so we - // can ignore this issue. - ty::Ref(..) => PatKind::Deref { subpattern: subpatterns.next().unwrap() }, - ty::Slice(_) | ty::Array(..) => bug!("bad slice pattern {:?} {:?}", self, pcx.ty), - _ => PatKind::Wild, - }, - Slice(slice) => match slice.kind { - FixedLen(_) => { - PatKind::Slice { prefix: subpatterns.collect(), slice: None, suffix: vec![] } - } - VarLen(prefix, _) => { - let mut prefix: Vec<_> = subpatterns.by_ref().take(prefix as usize).collect(); - if slice.array_len.is_some() { - // Improves diagnostics a bit: if the type is a known-size array, instead - // of reporting `[x, _, .., _, y]`, we prefer to report `[x, .., y]`. - // This is incorrect if the size is not known, since `[_, ..]` captures - // arrays of lengths `>= 1` whereas `[..]` captures any length. - while !prefix.is_empty() && prefix.last().unwrap().is_wildcard() { - prefix.pop(); - } - } - let suffix: Vec<_> = if slice.array_len.is_some() { - // Same as above. - subpatterns.skip_while(Pat::is_wildcard).collect() - } else { - subpatterns.collect() - }; - let wild = Pat::wildcard_from_ty(pcx.ty); - PatKind::Slice { prefix, slice: Some(wild), suffix } - } - }, - &Str(value) => PatKind::Constant { value }, - &FloatRange(lo, hi, end) => PatKind::Range(PatRange { lo, hi, end }), - IntRange(range) => return range.to_pat(pcx.cx.tcx), - NonExhaustive => PatKind::Wild, - Opaque => bug!("we should not try to apply an opaque constructor"), - Wildcard => bug!( - "trying to apply a wildcard constructor; this should have been done in `apply_constructors`" - ), - }; - - Pat { ty: pcx.ty, span: DUMMY_SP, kind: Box::new(pat) } - } } /// Some fields need to be explicitly hidden away in certain cases; see the comment above the @@ -1228,6 +1141,93 @@ impl<'p, 'tcx> Fields<'p, 'tcx> { ret } + /// Apply a constructor to a list of patterns, yielding a new pattern. `self` + /// must have as many elements as this constructor's arity. + /// + /// This is roughly the inverse of `specialize_constructor`. + /// + /// Examples: + /// `ctor`: `Constructor::Single` + /// `ty`: `Foo(u32, u32, u32)` + /// `self`: `[10, 20, _]` + /// returns `Foo(10, 20, _)` + /// + /// `ctor`: `Constructor::Variant(Option::Some)` + /// `ty`: `Option<bool>` + /// `self`: `[false]` + /// returns `Some(false)` + fn apply(self, pcx: PatCtxt<'_, 'p, 'tcx>, ctor: &Constructor<'tcx>) -> Pat<'tcx> { + let mut subpatterns = self.all_patterns(); + + let pat = match ctor { + Single | Variant(_) => match pcx.ty.kind() { + ty::Adt(..) | ty::Tuple(..) => { + let subpatterns = subpatterns + .enumerate() + .map(|(i, p)| FieldPat { field: Field::new(i), pattern: p }) + .collect(); + + if let ty::Adt(adt, substs) = pcx.ty.kind() { + if adt.is_enum() { + PatKind::Variant { + adt_def: adt, + substs, + variant_index: ctor.variant_index_for_adt(adt), + subpatterns, + } + } else { + PatKind::Leaf { subpatterns } + } + } else { + PatKind::Leaf { subpatterns } + } + } + // Note: given the expansion of `&str` patterns done in `expand_pattern`, we should + // be careful to reconstruct the correct constant pattern here. However a string + // literal pattern will never be reported as a non-exhaustiveness witness, so we + // can ignore this issue. + ty::Ref(..) => PatKind::Deref { subpattern: subpatterns.next().unwrap() }, + ty::Slice(_) | ty::Array(..) => bug!("bad slice pattern {:?} {:?}", ctor, pcx.ty), + _ => PatKind::Wild, + }, + Slice(slice) => match slice.kind { + FixedLen(_) => { + PatKind::Slice { prefix: subpatterns.collect(), slice: None, suffix: vec![] } + } + VarLen(prefix, _) => { + let mut prefix: Vec<_> = subpatterns.by_ref().take(prefix as usize).collect(); + if slice.array_len.is_some() { + // Improves diagnostics a bit: if the type is a known-size array, instead + // of reporting `[x, _, .., _, y]`, we prefer to report `[x, .., y]`. + // This is incorrect if the size is not known, since `[_, ..]` captures + // arrays of lengths `>= 1` whereas `[..]` captures any length. + while !prefix.is_empty() && prefix.last().unwrap().is_wildcard() { + prefix.pop(); + } + } + let suffix: Vec<_> = if slice.array_len.is_some() { + // Same as above. + subpatterns.skip_while(Pat::is_wildcard).collect() + } else { + subpatterns.collect() + }; + let wild = Pat::wildcard_from_ty(pcx.ty); + PatKind::Slice { prefix, slice: Some(wild), suffix } + } + }, + &Str(value) => PatKind::Constant { value }, + &FloatRange(lo, hi, end) => PatKind::Range(PatRange { lo, hi, end }), + IntRange(range) => return range.to_pat(pcx.cx.tcx), + NonExhaustive => PatKind::Wild, + Opaque => bug!("we should not try to apply an opaque constructor"), + Wildcard => bug!( + "trying to apply a wildcard constructor; this should have been done in `apply_constructors`" + ), + }; + + Pat { ty: pcx.ty, span: DUMMY_SP, kind: Box::new(pat) } + } + /// Returns the number of patterns from the viewpoint of match-checking, i.e. excluding hidden /// fields. This is what we want in most cases in this file, the only exception being /// conversion to/from `Pat`. @@ -1534,8 +1534,7 @@ impl<'tcx> Witness<'tcx> { let len = self.0.len(); let arity = ctor_wild_subpatterns.len(); let pats = self.0.drain((len - arity)..).rev(); - let fields = ctor_wild_subpatterns.replace_fields(pcx.cx, pats); - ctor.apply(pcx, fields) + ctor_wild_subpatterns.replace_fields(pcx.cx, pats).apply(pcx, ctor) }; self.0.push(pat); @@ -2072,10 +2071,7 @@ impl<'tcx> MissingConstructors<'tcx> { // it. For example, if `ctor` is a `Constructor::Variant` for // `Option::Some`, we get the pattern `Some(_)`. self.iter(pcx) - .map(|missing_ctor| { - let fields = Fields::wildcards(pcx, &missing_ctor); - missing_ctor.apply(pcx, fields) - }) + .map(|missing_ctor| Fields::wildcards(pcx, &missing_ctor).apply(pcx, missing_ctor)) .collect() } } |