Open Radar

 
Summary:
If I have func a(x: Int?), I can guard let x = x else { return }, and this works fine. I love this, because it lets me avoid unnecessary nesting without having to fiddle with names.

But if, within a(_:), I do let b = maybeInt(); guard let b = b else { return }, I get a redefinition error for b. This is frustrating; now I need to do something like let maybeB = maybeInt(); guard let b = maybeB else { return }.

It seems weird that the let-bound function parameter can be shadowed, but not the let-bound local name.

Steps to Reproduce:
> swift
(.lldbinit loaded)
fcWelcome to Apple Swift version 2.0 (700.0.57 700.0.72). Type :help for assistance.
  1> func b() -> Int? { return 3 }
  2> func a(x: Int?) {
  3.     guard let x = x else { return }
  4.     let y = b()
  5.     guard let y = y else { return }
  6.     print(x, y)
  7. }
repl.swift:5:15: error: definition conflicts with previous value
    guard let y = y else { return }
              ^
repl.swift:4:9: note: previous definition of 'y' is here
    let y = b()
        ^


Expected Results:
b is shadowed for the rest of the method body with the unwrapped value of b, so that b: Int? is replaced with b: Int.

This would be identical to the handling of the let-bound function argument name.

Actual Results:
repl.swift:5:15: error: definition conflicts with previous value
    guard let y = y else { return }
              ^
repl.swift:4:9: note: previous definition of 'y' is here
    let y = b()
        ^

Version:
Apple Swift version 2.0 (swiftlang-700.0.57.3 clang-700.0.72)
Target: x86_64-apple-darwin14.5.0

Xcode 7.0
Build version 7A192o

ProductName:	Mac OS X
ProductVersion:	10.10.5
BuildVersion:	14F27


Notes:


Configuration:


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