Typecheck let bindings using annotated type instead of inferred type #5080
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abs0luty
commented
Oct 26, 2025
abs0luty
commented
- Closes let bindings are typechecked using their inferred type not their (narrowed) annotated type #4642
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lpil
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Oct 27, 2025
...ore/src/type_/tests/snapshots/gleam_core__type___tests__errors__module_could_not_unify9.snap
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lpil
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Dec 4, 2025
```gleam
pub fn main() {
let x: String = 5 // type error: expected String, got Int
let y: Int = x // valid
let z: String = x // type error: expected String, got Int
}
```
Fix type checking after annotated let errors so the compiler trusts the user annotation
and reports follow up errors on uses that rely on that annotated type.
A let binding that fails its annotation no longer causes later checks to use the
inferred type, which avoids misleading errors and flags the incorrect assignment earlier in the code.
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