[SR-3417] #if in closure doesn't allow closure to be a single expression closure

[swift-ci]

Previous ID	SR-3417
Radar	None
Original Reporter	hughbe (JIRA User)
Type	Bug
Status	Resolved
Resolution	Done

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, Parser, TypeChecker
Assignee	maustinstar (JIRA)
Priority	Medium

md5: 9e8c4f62db5afe1e6df957fc5c116a33

Issue Description:

The following code feels like it should work, but doesn't

public func _stdlib_pipe() -> (readEnd: CInt, writeEnd: CInt, error: CInt) {
  var fds: [CInt] = [0, 0]
  let ret = fds.withUnsafeMutableBufferPointer { unsafeFds -> CInt in
#if !os(Windows) || CYGWIN
    pipe(unsafeFds.baseAddress)
#else
    _pipe(unsafeFds.baseAddress, 0, 0)
#endif
  }
  return (readEnd: fds[0], writeEnd: fds[1], error: ret)
}

Instead, you need to include an explicit return as the closure can no longer be a single expression closure.

public func _stdlib_pipe() -> (readEnd: CInt, writeEnd: CInt, error: CInt) {
  var fds: [CInt] = [0, 0]
  let ret = fds.withUnsafeMutableBufferPointer { unsafeFds -> CInt in
#if !os(Windows) || CYGWIN
    return pipe(unsafeFds.baseAddress)
#else
    return _pipe(unsafeFds.baseAddress, 0, 0)
#endif
  }
  return (readEnd: fds[0], writeEnd: fds[1], error: ret)
}

[swift-ci]

Comment by Michael Verges (JIRA)

PR: #34510