Attachment: Download

Issue Description:

Environment

$ git log --oneline -n1
87d73e9 Merge pull request #​2708 from jckarter/bridging-objc-generic-containers

$ ls -l $(which python)
lrwxr-xr-x  1 Jacob  admin  34 May 26 19:14 /usr/local/bin/python -> ../Cellar/python/2.7.11/bin/python

$ sw_vers
ProductName:    Mac OS X
ProductVersion: 10.11.5
BuildVersion:   15F34

$ plutil -p $(xcode-select --print-path)/../../Contents/version.plist
{
  "CFBundleShortVersionString" => "7.3.1"
  "BuildVersion" => "3"
  "ProductBuildVersion" => "7D1012"
  "ProjectName" => "IDEFrameworks"
  "SourceVersion" => "10188000000000000"
  "CFBundleVersion" => "10188"
}

Steps to reproduce

1. Install Python via Homebrew: brew install python
2. Run build-script -x (starting with a clean tree; or also add -c)

Observed

• The build proceeds for a while, but eventually freezes with all 8 workers sitting in Python processes (see attached screenshot).

• Pressing ⌃C and re-running build-script -x will often freeze at a slightly different command, but it's always a gyb line (line breaks are my own addition):

  cd /Users/Jacob/Development/swift/swift/stdlib/public/core && \
  /Users/Jacob/Development/swift/swift/utils/gyb --test \
  -DunicodeGraphemeBreakPropertyFile=/Users/Jacob/Development/swift/swift/utils/UnicodeData/GraphemeBreakProperty.txt \
  -DunicodeGraphemeBreakTestFile=/Users/Jacob/Development/swift/swift/utils/UnicodeData/GraphemeBreakTest.txt \
  -DCMAKE_SIZEOF_VOID_P=8 \
  -o /Users/Jacob/Development/swift/build/Xcode-DebugAssert/swift-macosx-x86_64/stdlib/public/core/8/Indices.swift.tmp \
  Indices.swift.gyb
  

• Breaking with ⌃C results in this stack trace:

  ^C** BUILD INTERRUPTED **
  Traceback (most recent call last):
    File "utils/build-script", line 1444, in <module>
      sys.exit(main())
    File "utils/build-script", line 1440, in main
      return main_normal()
    File "utils/build-script", line 1398, in main_normal
      disable_sleep=True)
    File "/Users/Jacob/Development/swift/swift/utils/SwiftBuildSupport.py", line 86, in check_call
      return subprocess.check_call(args)
    File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 535, in check_call
      retcode = call(*popenargs, **kwargs)
    File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 522, in call
      return Popen(*popenargs, **kwargs).wait()
    File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 1384, in wait
      pid, sts = _eintr_retry_call(os.waitpid, self.pid, 0)
    File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 476, in _eintr_retry_call
      return func(*args)
  KeyboardInterrupt
  

• Manually running the above gyb command from a shell seems to succeed.

Workaround

Running brew unlink python to revert to the system version of Python seems to resolve the issue.