Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-ty/src/infer/pat.rs')
| -rw-r--r-- | crates/hir-ty/src/infer/pat.rs | 129 |
1 files changed, 105 insertions, 24 deletions
diff --git a/crates/hir-ty/src/infer/pat.rs b/crates/hir-ty/src/infer/pat.rs index 00398f019d..5ff22bea34 100644 --- a/crates/hir-ty/src/infer/pat.rs +++ b/crates/hir-ty/src/infer/pat.rs @@ -3,23 +3,24 @@ use std::iter::repeat_with; use hir_def::{ - body::Body, + expr_store::Body, hir::{Binding, BindingAnnotation, BindingId, Expr, ExprId, Literal, Pat, PatId}, path::Path, + HasModule, }; use hir_expand::name::Name; use stdx::TupleExt; use crate::{ - consteval::{try_const_usize, usize_const}, + consteval::{self, try_const_usize, usize_const}, infer::{ coerce::CoerceNever, expr::ExprIsRead, BindingMode, Expectation, InferenceContext, TypeMismatch, }, lower::lower_to_chalk_mutability, primitive::UintTy, - static_lifetime, InferenceDiagnostic, Interner, Mutability, Scalar, Substitution, Ty, - TyBuilder, TyExt, TyKind, + static_lifetime, DeclContext, DeclOrigin, InferenceDiagnostic, Interner, Mutability, Scalar, + Substitution, Ty, TyBuilder, TyExt, TyKind, }; impl InferenceContext<'_> { @@ -34,6 +35,7 @@ impl InferenceContext<'_> { id: PatId, ellipsis: Option<u32>, subs: &[PatId], + decl: Option<DeclContext>, ) -> Ty { let (ty, def) = self.resolve_variant(id.into(), path, true); let var_data = def.map(|it| it.variant_data(self.db.upcast())); @@ -92,13 +94,13 @@ impl InferenceContext<'_> { } }; - self.infer_pat(subpat, &expected_ty, default_bm); + self.infer_pat(subpat, &expected_ty, default_bm, decl); } } None => { let err_ty = self.err_ty(); for &inner in subs { - self.infer_pat(inner, &err_ty, default_bm); + self.infer_pat(inner, &err_ty, default_bm, decl); } } } @@ -114,6 +116,7 @@ impl InferenceContext<'_> { default_bm: BindingMode, id: PatId, subs: impl ExactSizeIterator<Item = (Name, PatId)>, + decl: Option<DeclContext>, ) -> Ty { let (ty, def) = self.resolve_variant(id.into(), path, false); if let Some(variant) = def { @@ -162,13 +165,13 @@ impl InferenceContext<'_> { } }; - self.infer_pat(inner, &expected_ty, default_bm); + self.infer_pat(inner, &expected_ty, default_bm, decl); } } None => { let err_ty = self.err_ty(); for (_, inner) in subs { - self.infer_pat(inner, &err_ty, default_bm); + self.infer_pat(inner, &err_ty, default_bm, decl); } } } @@ -185,6 +188,7 @@ impl InferenceContext<'_> { default_bm: BindingMode, ellipsis: Option<u32>, subs: &[PatId], + decl: Option<DeclContext>, ) -> Ty { let expected = self.resolve_ty_shallow(expected); let expectations = match expected.as_tuple() { @@ -209,12 +213,12 @@ impl InferenceContext<'_> { // Process pre for (ty, pat) in inner_tys.iter_mut().zip(pre) { - *ty = self.infer_pat(*pat, ty, default_bm); + *ty = self.infer_pat(*pat, ty, default_bm, decl); } // Process post for (ty, pat) in inner_tys.iter_mut().skip(pre.len() + n_uncovered_patterns).zip(post) { - *ty = self.infer_pat(*pat, ty, default_bm); + *ty = self.infer_pat(*pat, ty, default_bm, decl); } TyKind::Tuple(inner_tys.len(), Substitution::from_iter(Interner, inner_tys)) @@ -223,11 +227,17 @@ impl InferenceContext<'_> { /// The resolver needs to be updated to the surrounding expression when inside assignment /// (because there, `Pat::Path` can refer to a variable). - pub(super) fn infer_top_pat(&mut self, pat: PatId, expected: &Ty) { - self.infer_pat(pat, expected, BindingMode::default()); + pub(super) fn infer_top_pat(&mut self, pat: PatId, expected: &Ty, decl: Option<DeclContext>) { + self.infer_pat(pat, expected, BindingMode::default(), decl); } - fn infer_pat(&mut self, pat: PatId, expected: &Ty, mut default_bm: BindingMode) -> Ty { + fn infer_pat( + &mut self, + pat: PatId, + expected: &Ty, + mut default_bm: BindingMode, + decl: Option<DeclContext>, + ) -> Ty { let mut expected = self.resolve_ty_shallow(expected); if matches!(&self.body[pat], Pat::Ref { .. }) || self.inside_assignment { @@ -261,11 +271,11 @@ impl InferenceContext<'_> { let ty = match &self.body[pat] { Pat::Tuple { args, ellipsis } => { - self.infer_tuple_pat_like(&expected, default_bm, *ellipsis, args) + self.infer_tuple_pat_like(&expected, default_bm, *ellipsis, args, decl) } Pat::Or(pats) => { for pat in pats.iter() { - self.infer_pat(*pat, &expected, default_bm); + self.infer_pat(*pat, &expected, default_bm, decl); } expected.clone() } @@ -274,6 +284,7 @@ impl InferenceContext<'_> { lower_to_chalk_mutability(mutability), &expected, default_bm, + decl, ), Pat::TupleStruct { path: p, args: subpats, ellipsis } => self .infer_tuple_struct_pat_like( @@ -283,10 +294,11 @@ impl InferenceContext<'_> { pat, *ellipsis, subpats, + decl, ), Pat::Record { path: p, args: fields, ellipsis: _ } => { let subs = fields.iter().map(|f| (f.name.clone(), f.pat)); - self.infer_record_pat_like(p.as_deref(), &expected, default_bm, pat, subs) + self.infer_record_pat_like(p.as_deref(), &expected, default_bm, pat, subs, decl) } Pat::Path(path) => { let ty = self.infer_path(path, pat.into()).unwrap_or_else(|| self.err_ty()); @@ -319,10 +331,10 @@ impl InferenceContext<'_> { } } Pat::Bind { id, subpat } => { - return self.infer_bind_pat(pat, *id, default_bm, *subpat, &expected); + return self.infer_bind_pat(pat, *id, default_bm, *subpat, &expected, decl); } Pat::Slice { prefix, slice, suffix } => { - self.infer_slice_pat(&expected, prefix, slice, suffix, default_bm) + self.infer_slice_pat(&expected, prefix, slice, suffix, default_bm, decl) } Pat::Wild => expected.clone(), Pat::Range { .. } => { @@ -345,7 +357,7 @@ impl InferenceContext<'_> { _ => (self.result.standard_types.unknown.clone(), None), }; - let inner_ty = self.infer_pat(*inner, &inner_ty, default_bm); + let inner_ty = self.infer_pat(*inner, &inner_ty, default_bm, decl); let mut b = TyBuilder::adt(self.db, box_adt).push(inner_ty); if let Some(alloc_ty) = alloc_ty { @@ -420,6 +432,7 @@ impl InferenceContext<'_> { mutability: Mutability, expected: &Ty, default_bm: BindingMode, + decl: Option<DeclContext>, ) -> Ty { let (expectation_type, expectation_lt) = match expected.as_reference() { Some((inner_ty, lifetime, _exp_mut)) => (inner_ty.clone(), lifetime.clone()), @@ -433,7 +446,7 @@ impl InferenceContext<'_> { (inner_ty, inner_lt) } }; - let subty = self.infer_pat(inner_pat, &expectation_type, default_bm); + let subty = self.infer_pat(inner_pat, &expectation_type, default_bm, decl); TyKind::Ref(mutability, expectation_lt, subty).intern(Interner) } @@ -444,6 +457,7 @@ impl InferenceContext<'_> { default_bm: BindingMode, subpat: Option<PatId>, expected: &Ty, + decl: Option<DeclContext>, ) -> Ty { let Binding { mode, .. } = self.body.bindings[binding]; let mode = if mode == BindingAnnotation::Unannotated { @@ -454,7 +468,7 @@ impl InferenceContext<'_> { self.result.binding_modes.insert(pat, mode); let inner_ty = match subpat { - Some(subpat) => self.infer_pat(subpat, expected, default_bm), + Some(subpat) => self.infer_pat(subpat, expected, default_bm, decl), None => expected.clone(), }; let inner_ty = self.insert_type_vars_shallow(inner_ty); @@ -478,14 +492,28 @@ impl InferenceContext<'_> { slice: &Option<PatId>, suffix: &[PatId], default_bm: BindingMode, + decl: Option<DeclContext>, ) -> Ty { + let expected = self.resolve_ty_shallow(expected); + + // If `expected` is an infer ty, we try to equate it to an array if the given pattern + // allows it. See issue #16609 + if self.pat_is_irrefutable(decl) && expected.is_ty_var() { + if let Some(resolved_array_ty) = + self.try_resolve_slice_ty_to_array_ty(prefix, suffix, slice) + { + self.unify(&expected, &resolved_array_ty); + } + } + + let expected = self.resolve_ty_shallow(&expected); let elem_ty = match expected.kind(Interner) { TyKind::Array(st, _) | TyKind::Slice(st) => st.clone(), _ => self.err_ty(), }; for &pat_id in prefix.iter().chain(suffix.iter()) { - self.infer_pat(pat_id, &elem_ty, default_bm); + self.infer_pat(pat_id, &elem_ty, default_bm, decl); } if let &Some(slice_pat_id) = slice { @@ -499,7 +527,7 @@ impl InferenceContext<'_> { _ => TyKind::Slice(elem_ty.clone()), } .intern(Interner); - self.infer_pat(slice_pat_id, &rest_pat_ty, default_bm); + self.infer_pat(slice_pat_id, &rest_pat_ty, default_bm, decl); } match expected.kind(Interner) { @@ -528,7 +556,7 @@ impl InferenceContext<'_> { self.infer_expr(expr, &Expectation::has_type(expected.clone()), ExprIsRead::Yes) } - fn is_non_ref_pat(&mut self, body: &hir_def::body::Body, pat: PatId) -> bool { + fn is_non_ref_pat(&mut self, body: &hir_def::expr_store::Body, pat: PatId) -> bool { match &body[pat] { Pat::Tuple { .. } | Pat::TupleStruct { .. } @@ -553,6 +581,59 @@ impl InferenceContext<'_> { | Pat::Expr(_) => false, } } + + fn try_resolve_slice_ty_to_array_ty( + &mut self, + before: &[PatId], + suffix: &[PatId], + slice: &Option<PatId>, + ) -> Option<Ty> { + if !slice.is_none() { + return None; + } + + let len = before.len() + suffix.len(); + let size = + consteval::usize_const(self.db, Some(len as u128), self.owner.krate(self.db.upcast())); + + let elem_ty = self.table.new_type_var(); + let array_ty = TyKind::Array(elem_ty.clone(), size).intern(Interner); + Some(array_ty) + } + + /// Used to determine whether we can infer the expected type in the slice pattern to be of type array. + /// This is only possible if we're in an irrefutable pattern. If we were to allow this in refutable + /// patterns we wouldn't e.g. report ambiguity in the following situation: + /// + /// ```ignore(rust) + /// struct Zeroes; + /// const ARR: [usize; 2] = [0; 2]; + /// const ARR2: [usize; 2] = [2; 2]; + /// + /// impl Into<&'static [usize; 2]> for Zeroes { + /// fn into(self) -> &'static [usize; 2] { + /// &ARR + /// } + /// } + /// + /// impl Into<&'static [usize]> for Zeroes { + /// fn into(self) -> &'static [usize] { + /// &ARR2 + /// } + /// } + /// + /// fn main() { + /// let &[a, b]: &[usize] = Zeroes.into() else { + /// .. + /// }; + /// } + /// ``` + /// + /// If we're in an irrefutable pattern we prefer the array impl candidate given that + /// the slice impl candidate would be rejected anyway (if no ambiguity existed). + fn pat_is_irrefutable(&self, decl_ctxt: Option<DeclContext>) -> bool { + matches!(decl_ctxt, Some(DeclContext { origin: DeclOrigin::LocalDecl { has_else: false } })) + } } pub(super) fn contains_explicit_ref_binding(body: &Body, pat_id: PatId) -> bool { |