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Merge #3114

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3114: Don't let unknown match arms fall back to ! r=kjeremy a=flodiebold



Co-authored-by: Florian Diebold <flodiebold@gmail.com>
This commit is contained in:
bors[bot] 2020-02-11 20:48:31 +00:00 committed by GitHub
commit 6f685df681
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2 changed files with 22 additions and 1 deletions
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6
crates/ra_hir_ty/src/infer/expr.rs
View file

@ -165,7 +165,11 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
Expr::Match { expr, arms } => {
let input_ty = self.infer_expr(*expr, &Expectation::none());
let mut result_ty = self.table.new_maybe_never_type_var();
let mut result_ty = if arms.len() == 0 {
Ty::simple(TypeCtor::Never)
} else {
self.table.new_type_var()
};
for arm in arms {
let _pat_ty = self.infer_pat(arm.pat, &input_ty, BindingMode::default());

17
crates/ra_hir_ty/src/tests/never_type.rs
View file

@ -101,6 +101,7 @@ fn test() {
);
assert_eq!(t, "Option<i32>");
}
#[test]
fn never_type_can_be_reinferred3() {
let t = type_at(
@ -137,6 +138,22 @@ fn test(a: Void) {
assert_eq!(t, "!");
}
#[test]
fn match_unknown_arm() {
let t = type_at(
r#"
//- /main.rs
fn test(a: Option) {
let t = match 0 {
_ => unknown,
};
t<|>;
}
"#,
);
assert_eq!(t, "{unknown}");
}
#[test]
fn if_never() {
let t = type_at(