Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-ty/src/infer/coerce.rs')
| -rw-r--r-- | crates/hir-ty/src/infer/coerce.rs | 60 |
1 files changed, 44 insertions, 16 deletions
diff --git a/crates/hir-ty/src/infer/coerce.rs b/crates/hir-ty/src/infer/coerce.rs index 3293534a06..48c9153026 100644 --- a/crates/hir-ty/src/infer/coerce.rs +++ b/crates/hir-ty/src/infer/coerce.rs @@ -50,11 +50,44 @@ fn success( #[derive(Clone, Debug)] pub(super) struct CoerceMany { expected_ty: Ty, + final_ty: Option<Ty>, } impl CoerceMany { pub(super) fn new(expected: Ty) -> Self { - CoerceMany { expected_ty: expected } + CoerceMany { expected_ty: expected, final_ty: None } + } + + /// Returns the "expected type" with which this coercion was + /// constructed. This represents the "downward propagated" type + /// that was given to us at the start of typing whatever construct + /// we are typing (e.g., the match expression). + /// + /// Typically, this is used as the expected type when + /// type-checking each of the alternative expressions whose types + /// we are trying to merge. + pub(super) fn expected_ty(&self) -> Ty { + self.expected_ty.clone() + } + + /// Returns the current "merged type", representing our best-guess + /// at the LUB of the expressions we've seen so far (if any). This + /// isn't *final* until you call `self.complete()`, which will return + /// the merged type. + pub(super) fn merged_ty(&self) -> Ty { + self.final_ty.clone().unwrap_or_else(|| self.expected_ty.clone()) + } + + pub(super) fn complete(self, ctx: &mut InferenceContext<'_>) -> Ty { + if let Some(final_ty) = self.final_ty { + final_ty + } else { + ctx.result.standard_types.never.clone() + } + } + + pub(super) fn coerce_forced_unit(&mut self, ctx: &mut InferenceContext<'_>) { + self.coerce(ctx, None, &ctx.result.standard_types.unit.clone()) } /// Merge two types from different branches, with possible coercion. @@ -76,25 +109,25 @@ impl CoerceMany { // Special case: two function types. Try to coerce both to // pointers to have a chance at getting a match. See // https://github.com/rust-lang/rust/blob/7b805396bf46dce972692a6846ce2ad8481c5f85/src/librustc_typeck/check/coercion.rs#L877-L916 - let sig = match (self.expected_ty.kind(Interner), expr_ty.kind(Interner)) { + let sig = match (self.merged_ty().kind(Interner), expr_ty.kind(Interner)) { (TyKind::FnDef(..) | TyKind::Closure(..), TyKind::FnDef(..) | TyKind::Closure(..)) => { // FIXME: we're ignoring safety here. To be more correct, if we have one FnDef and one Closure, // we should be coercing the closure to a fn pointer of the safety of the FnDef cov_mark::hit!(coerce_fn_reification); let sig = - self.expected_ty.callable_sig(ctx.db).expect("FnDef without callable sig"); + self.merged_ty().callable_sig(ctx.db).expect("FnDef without callable sig"); Some(sig) } _ => None, }; if let Some(sig) = sig { let target_ty = TyKind::Function(sig.to_fn_ptr()).intern(Interner); - let result1 = ctx.table.coerce_inner(self.expected_ty.clone(), &target_ty); + let result1 = ctx.table.coerce_inner(self.merged_ty(), &target_ty); let result2 = ctx.table.coerce_inner(expr_ty.clone(), &target_ty); if let (Ok(result1), Ok(result2)) = (result1, result2) { ctx.table.register_infer_ok(result1); ctx.table.register_infer_ok(result2); - return self.expected_ty = target_ty; + return self.final_ty = Some(target_ty); } } @@ -102,25 +135,20 @@ impl CoerceMany { // type is a type variable and the new one is `!`, trying it the other // way around first would mean we make the type variable `!`, instead of // just marking it as possibly diverging. - if ctx.coerce(expr, &expr_ty, &self.expected_ty).is_ok() { - /* self.expected_ty is already correct */ - } else if ctx.coerce(expr, &self.expected_ty, &expr_ty).is_ok() { - self.expected_ty = expr_ty; + if let Ok(res) = ctx.coerce(expr, &expr_ty, &self.merged_ty()) { + self.final_ty = Some(res); + } else if let Ok(res) = ctx.coerce(expr, &self.merged_ty(), &expr_ty) { + self.final_ty = Some(res); } else { if let Some(id) = expr { ctx.result.type_mismatches.insert( id.into(), - TypeMismatch { expected: self.expected_ty.clone(), actual: expr_ty }, + TypeMismatch { expected: self.merged_ty().clone(), actual: expr_ty.clone() }, ); } cov_mark::hit!(coerce_merge_fail_fallback); - /* self.expected_ty is already correct */ } } - - pub(super) fn complete(self) -> Ty { - self.expected_ty - } } pub fn could_coerce( @@ -665,7 +693,7 @@ pub(super) fn auto_deref_adjust_steps(autoderef: &Autoderef<'_, '_>) -> Vec<Adju .iter() .map(|(kind, _source)| match kind { // We do not know what kind of deref we require at this point yet - AutoderefKind::Overloaded => Some(OverloadedDeref(Mutability::Not)), + AutoderefKind::Overloaded => Some(OverloadedDeref(None)), AutoderefKind::Builtin => None, }) .zip(targets) |