diff options
author | Mikail Bagishov <[email protected]> | 2020-05-06 15:45:47 +0100 |
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committer | Mikail Bagishov <[email protected]> | 2020-05-06 15:59:27 +0100 |
commit | 7c94fa7d01f264e5268ab5f57519f071c00a6579 (patch) | |
tree | b0ef8b6a9f8653519b70bd0a3726c374f2c6d128 /crates/ra_hir_ty/src/_match.rs | |
parent | efd8e34c396f1524623a495e47111f1047cf2879 (diff) |
Fix usefulness check for never type
Diffstat (limited to 'crates/ra_hir_ty/src/_match.rs')
-rw-r--r-- | crates/ra_hir_ty/src/_match.rs | 29 |
1 files changed, 23 insertions, 6 deletions
diff --git a/crates/ra_hir_ty/src/_match.rs b/crates/ra_hir_ty/src/_match.rs index 779e78574..149f65042 100644 --- a/crates/ra_hir_ty/src/_match.rs +++ b/crates/ra_hir_ty/src/_match.rs | |||
@@ -573,14 +573,20 @@ pub(crate) fn is_useful( | |||
573 | matrix: &Matrix, | 573 | matrix: &Matrix, |
574 | v: &PatStack, | 574 | v: &PatStack, |
575 | ) -> MatchCheckResult<Usefulness> { | 575 | ) -> MatchCheckResult<Usefulness> { |
576 | // Handle the special case of enums with no variants. In that case, no match | 576 | // Handle two special cases: |
577 | // arm is useful. | 577 | // - enum with no variants |
578 | if let Ty::Apply(ApplicationTy { ctor: TypeCtor::Adt(AdtId::EnumId(enum_id)), .. }) = | 578 | // - `!` type |
579 | cx.infer[cx.match_expr].strip_references() | 579 | // In those cases, no match arm is useful. |
580 | { | 580 | match cx.infer[cx.match_expr].strip_references() { |
581 | if cx.db.enum_data(*enum_id).variants.is_empty() { | 581 | Ty::Apply(ApplicationTy { ctor: TypeCtor::Adt(AdtId::EnumId(enum_id)), .. }) => { |
582 | if cx.db.enum_data(*enum_id).variants.is_empty() { | ||
583 | return Ok(Usefulness::NotUseful); | ||
584 | } | ||
585 | } | ||
586 | Ty::Apply(ApplicationTy { ctor: TypeCtor::Never, .. }) => { | ||
582 | return Ok(Usefulness::NotUseful); | 587 | return Ok(Usefulness::NotUseful); |
583 | } | 588 | } |
589 | _ => (), | ||
584 | } | 590 | } |
585 | 591 | ||
586 | if v.is_empty() { | 592 | if v.is_empty() { |
@@ -1918,6 +1924,17 @@ mod tests { | |||
1918 | } | 1924 | } |
1919 | 1925 | ||
1920 | #[test] | 1926 | #[test] |
1927 | fn type_never() { | ||
1928 | let content = r" | ||
1929 | fn test_fn(never: !) { | ||
1930 | match never {} | ||
1931 | } | ||
1932 | "; | ||
1933 | |||
1934 | check_no_diagnostic(content); | ||
1935 | } | ||
1936 | |||
1937 | #[test] | ||
1921 | fn enum_never_ref() { | 1938 | fn enum_never_ref() { |
1922 | let content = r" | 1939 | let content = r" |
1923 | enum Never {} | 1940 | enum Never {} |