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feat: type inference for if-let guards

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This commit is contained in:
Jonas Schievink 2021-08-14 00:09:30 +02:00
parent 0d5408195e
commit 4757679b9a
2 changed files with 31 additions and 6 deletions
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20
crates/hir_ty/src/infer/expr.rs
View file

@ -366,13 +366,21 @@ impl<'a> InferenceContext<'a> {
for arm in arms {
self.diverges = Diverges::Maybe;
let _pat_ty = self.infer_pat(arm.pat, &input_ty, BindingMode::default());
if let Some(MatchGuard::If { expr: guard_expr }) = arm.guard {
self.infer_expr(
guard_expr,
&Expectation::has_type(TyKind::Scalar(Scalar::Bool).intern(&Interner)),
);
match arm.guard {
Some(MatchGuard::If { expr: guard_expr }) => {
self.infer_expr(
guard_expr,
&Expectation::has_type(
TyKind::Scalar(Scalar::Bool).intern(&Interner),
),
);
}
Some(MatchGuard::IfLet { expr, pat }) => {
let input_ty = self.infer_expr(expr, &Expectation::none());
let _pat_ty = self.infer_pat(pat, &input_ty, BindingMode::default());
}
_ => {}
}
// FIXME: infer `if let` guard
let arm_ty = self.infer_expr_inner(arm.expr, &expected);
all_arms_diverge &= self.diverges;

17
crates/hir_ty/src/tests/patterns.rs
View file

@ -916,3 +916,20 @@ fn main() {
"#,
);
}
#[test]
fn if_let_guards() {
check_types(
r#"
fn main() {
match (0,) {
opt if let (x,) = opt => {
x;
//^ i32
}
_ => {}
}
}
"#,
);
}