[SR-14382] Quick help shows incorrect type for dynamicMemberLookup property

[xAlien95]

Previous ID	SR-14382
Radar	rdar://problem/75697518
Original Reporter	@xAlien95
Type	Bug

Attachment: Download

Environment

Xcode 12.4 (12D4e)
Swift Development Snapshot 2021-03-20

Additional Detail from JIRA

Votes	0
Component/s	SourceKit-LSP
Labels	Bug
Assignee	None
Priority	Medium

md5: 8d53c1f81757b529593d97863e6c9773

Issue Description:

Consider the following snippet:

struct S {
  let foo: Int
}

@dynamicMemberLookup
struct W {
  subscript(dynamicMember keyPath: KeyPath<S, Int>) -> String {
    "Swift"
  }
}

// overviewed as "let foo: Int" (see attachment)
// suggested as "foo: String"
_ = W().foo

The underlying type is correct.

[typesanitizer]

@swift-ci create