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-rw-r--r--src/test/ui/issues/issue-67037-pat-tup-scrut-ty-diff-less-fields.rs21
-rw-r--r--src/test/ui/issues/issue-67037-pat-tup-scrut-ty-diff-less-fields.stderr22
2 files changed, 43 insertions, 0 deletions
diff --git a/src/test/ui/issues/issue-67037-pat-tup-scrut-ty-diff-less-fields.rs b/src/test/ui/issues/issue-67037-pat-tup-scrut-ty-diff-less-fields.rs
new file mode 100644
index 0000000..44bd645
--- /dev/null
+++ b/src/test/ui/issues/issue-67037-pat-tup-scrut-ty-diff-less-fields.rs
@@ -0,0 +1,21 @@
1// Regression test for #67037.
2//
3// In type checking patterns, E0023 occurs when the tuple pattern and the expected
4// tuple pattern have different number of fields. For example, as below, `P()`,
5// the tuple struct pattern, has 0 fields, but requires 1 field.
6//
7// In emitting E0023, we try to see if this is a case of e.g., `Some(a, b, c)` but where
8// the scrutinee was of type `Some((a, b, c))`, and suggest that parenthesis be added.
9//
10// However, we did not account for the expected type being different than the tuple pattern type.
11// This caused an issue when the tuple pattern type (`P<T>`) was generic.
12// Specifically, we tried deriving the 0th field's type using the `substs` of the expected type.
13// When attempting to substitute `T`, there was no such substitution, so "out of range" occured.
14
15struct U {} // 0 type parameters offered
16struct P<T>(T); // 1 type parameter wanted
17
18fn main() {
19 let P() = U {}; //~ ERROR mismatched types
20 //~^ ERROR this pattern has 0 fields, but the corresponding tuple struct has 1 field
21}
diff --git a/src/test/ui/issues/issue-67037-pat-tup-scrut-ty-diff-less-fields.stderr b/src/test/ui/issues/issue-67037-pat-tup-scrut-ty-diff-less-fields.stderr
new file mode 100644
index 0000000..521dd02
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+++ b/src/test/ui/issues/issue-67037-pat-tup-scrut-ty-diff-less-fields.stderr
@@ -0,0 +1,22 @@
1error[E0308]: mismatched types
2 --> $DIR/issue-67037-pat-tup-scrut-ty-diff-less-fields.rs:19:9
3 |
4LL | let P() = U {};
5 | ^^^ expected struct `U`, found struct `P`
6 |
7 = note: expected struct `U`
8 found struct `P<_>`
9
10error[E0023]: this pattern has 0 fields, but the corresponding tuple struct has 1 field
11 --> $DIR/issue-67037-pat-tup-scrut-ty-diff-less-fields.rs:19:9
12 |
13LL | struct P<T>(T); // 1 type parameter wanted
14 | --------------- tuple struct defined here
15...
16LL | let P() = U {};
17 | ^^^ expected 1 field, found 0
18
19error: aborting due to 2 previous errors
20
21Some errors have detailed explanations: E0023, E0308.
22For more information about an error, try `rustc --explain E0023`.