Pavel Yaskevich df44c4f4d7 [ConstraintSystem] Fix non-determinism in diagnoseAmbiguity ...

Simplification of member locator would produce a base expression,
this is what we want for diagnostics but not for comparisons in
`diagnoseAmbiguity` because base expression is located at a different
depth which would lead to incorrect results if both reference and base
expression are ambiguous e.g. `test[x].count` if both `[x]` and `count`
are ambiguous than simplification of `count` would produce `[x]` which
is incorrect.

This is the test-case (already in the suite) that exibits this behavior:

```
func test_ambiguity_with_placeholders(pairs: [(rank: Int, count: Int)]) -> Bool {
  return pairs[<#^ARG^#>].count == 2
}
```

Here subscript would either return a tuple or `ArraySlice` and
`count` is ambiguous because both have it.

2021-10-14 11:26:38 -07:00

220 KiB

Raw Blame History

View Raw