| // Regression test for #67037. |
| // |
| // In type checking patterns, E0023 occurs when the tuple pattern and the expected |
| // tuple pattern have different number of fields. For example, as below, `P()`, |
| // the tuple struct pattern, has 0 fields, but requires 1 field. |
| // |
| // In emitting E0023, we try to see if this is a case of e.g., `Some(a, b, c)` but where |
| // the scrutinee was of type `Some((a, b, c))`, and suggest that parentheses be added. |
| // |
| // However, we did not account for the expected type being different than the tuple pattern type. |
| // This caused an issue when the tuple pattern type (`P<T>`) was generic. |
| // Specifically, we tried deriving the 0th field's type using the `substs` of the expected type. |
| // When attempting to substitute `T`, there was no such substitution, so "out of range" occurred. |
| |
| struct U {} // 0 type parameters offered |
| struct P<T>(T); // 1 type parameter wanted |
| |
| fn main() { |
| let P() = U {}; //~ ERROR mismatched types |
| //~^ ERROR this pattern has 0 fields, but the corresponding tuple struct has 1 field |
| } |
