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Diffstat (limited to 'crates/hir-ty/src/infer/unify.rs')
| -rw-r--r-- | crates/hir-ty/src/infer/unify.rs | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/crates/hir-ty/src/infer/unify.rs b/crates/hir-ty/src/infer/unify.rs index a1fef48f25..e7ddd1591f 100644 --- a/crates/hir-ty/src/infer/unify.rs +++ b/crates/hir-ty/src/infer/unify.rs @@ -350,6 +350,51 @@ impl<'a> InferenceTable<'a> { self.resolve_with_fallback(t, &|_, _, d, _| d) } + /// Apply a fallback to unresolved scalar types. Integer type variables and float type + /// variables are replaced with i32 and f64, respectively. + /// + /// This method is only intended to be called just before returning inference results (i.e. in + /// `InferenceContext::resolve_all()`). + /// + /// FIXME: This method currently doesn't apply fallback to unconstrained general type variables + /// whereas rustc replaces them with `()` or `!`. + pub(super) fn fallback_if_possible(&mut self) { + let int_fallback = TyKind::Scalar(Scalar::Int(IntTy::I32)).intern(Interner); + let float_fallback = TyKind::Scalar(Scalar::Float(FloatTy::F64)).intern(Interner); + + let scalar_vars: Vec<_> = self + .type_variable_table + .iter() + .enumerate() + .filter_map(|(index, flags)| { + let kind = if flags.contains(TypeVariableFlags::INTEGER) { + TyVariableKind::Integer + } else if flags.contains(TypeVariableFlags::FLOAT) { + TyVariableKind::Float + } else { + return None; + }; + + // FIXME: This is not really the nicest way to get `InferenceVar`s. Can we get them + // without directly constructing them from `index`? + let var = InferenceVar::from(index as u32).to_ty(Interner, kind); + Some(var) + }) + .collect(); + + for var in scalar_vars { + let maybe_resolved = self.resolve_ty_shallow(&var); + if let TyKind::InferenceVar(_, kind) = maybe_resolved.kind(Interner) { + let fallback = match kind { + TyVariableKind::Integer => &int_fallback, + TyVariableKind::Float => &float_fallback, + TyVariableKind::General => unreachable!(), + }; + self.unify(&var, fallback); + } + } + } + /// Unify two relatable values (e.g. `Ty`) and register new trait goals that arise from that. pub(crate) fn unify<T: ?Sized + Zip<Interner>>(&mut self, ty1: &T, ty2: &T) -> bool { let result = match self.try_unify(ty1, ty2) { |