[SR-7933] SourceKit double-counts escaping and autoclosure attributes

Previous ID	SR-7933
Radar	None
Original Reporter	@natecook1000
Type	Improvement

Votes	0
Component/s	Source Tooling
Labels	Improvement, StarterBug
Assignee	None
Priority	Medium

md5: 065c0c3c9adc792d7d7203c32bd04ee2

Issue Description:

The @escaping and @autoclosure attributes are mapped differently from other attributes. For example, given this source code:

func a(_ b: @escaping () -> Bool) {}
@discardableResult func b() -> Int { return 0 }
func c(_ b: @autoclosure () -> Bool) {}

SourceKit yields this syntax map (unrelated pieces elided):

{
  key.offset: 0,
  key.length: 125,
  key.diagnostic_stage: source.diagnostic.stage.swift.parse,
  key.syntaxmap: [
    ...,
    {
      key.kind: source.lang.swift.syntaxtype.attribute.id,
      key.offset: 12,
      key.length: 9
    },
    {
      key.kind: source.lang.swift.syntaxtype.attribute.builtin,
      key.offset: 13,
      key.length: 8
    },
    ...,
    {
      key.kind: source.lang.swift.syntaxtype.attribute.builtin,
      key.offset: 37,
      key.length: 18
    },
    ...,
    {
      key.kind: source.lang.swift.syntaxtype.attribute.id,
      key.offset: 97,
      key.length: 12
    },
    {
      key.kind: source.lang.swift.syntaxtype.attribute.builtin,
      key.offset: 98,
      key.length: 11
    },
    ...
  ]
}

The "source.lang.swift.syntaxtype.attribute.builtin" keys should have the offset and length of the "source.lang.swift.syntaxtype.attribute.id" keys, which in turn shouldn't be emitted.