Pavel Yaskevich e3a5477bf9 [SwiftCompilerSources] Disfavor overload of == that takes StringRef ...

This overload is disfavored to make sure that it's only used for cases
that don't involve literals, for that `==(StringRef, StaticString) -> Bool`
is preferred. Otherwise these overloads are going to be ambiguous
because both `StringRef`, `StaticString` conform to `ExpressibleByStringLiteral`.

Consider the following example:

```swift
func test(lhs: StringRef) {
  lhs == "<<test>>"
}
```

The type-checker used to pick `==(StringRef, StringRef)` overload in this
case because it has homogenous parameter types but this is no longer the
case because this behavior was too aggressive and led to sub-optimal choices
by completely skipping other viable overloads.

Since `StaticString` already represents literals it's better to use
a standard library type and reserve the `(StringRef, StringRef)`
overload to when the literals are not involved.

Resolves: rdar://154719565

2025-07-03 16:57:28 -07:00

8.3 KiB

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