[SR-14258] Pattern-matching fails when enum case is type-qualified

[karwa]

Previous ID	SR-14258
Radar	rdar://problem/74616577
Original Reporter	@karwa
Type	Bug

Environment

Xcode Version 12.4 (12D4e)

macOS 10.15.7 (19H15)

Apple Swift version 5.3.2 (swiftlang-1200.0.45 clang-1200.0.32.28)

Target: x86_64-apple-darwin19.6.0

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug
Assignee	None
Priority	Medium

md5: 44f7392d58ba8233dcd512e04b5c643a

Issue Description:

enum Demo {
  case foo
  case bar
  case baz
}


func ~= (pattern: Demo, value: String) -> Bool {
  false
}


func a() {
  switch "" {
  case .foo, .bar:
    break
  case Demo.baz:   // < ERROR: Enum case 'baz' is not a member of type 'String'
    break
  default:
    break
  }
}

When referring to cases as ".foo" or ".bar", all is well. However, when using the type-qualified spelling "Demo.baz", the code fails to compile. Moreover, the diagnostic tells us that it... expects 'baz' to exist on String... but it knows its an enum case, soo... it must have seen the definition in 'Demo'? So why is it looking in String?

Weirdness.

[typesanitizer]

@swift-ci create

[ole]

Manual backlink: this issue was mentioned in this forum thread: How does ‘switch’ work? Not the same as if/else with pattern matching operator