[libcxx] Test case for the experimental library visibility macros

[hamzasood]

Summary

This patch adds a test case to ensure that every library header uses the correct visibility macros.
libc++ headers should use _LIBCPP_* macros whereas libc++experimental headers should use _LIBCPPX_* macros.

This was originally part of D37182, but it's been taken out for separate review as requested.
It's dependent on the aforementioned patch; the test will fail until that patch has been applied.

test/libcxx/selftest/experimental_visibility.sh.cpp

+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// RUN: check_experimental_visibility "%libcxx_src_root/include"
+

utils/check_experimental_visibility.py

+#!/usr/bin/env python
+#===----------------------------------------------------------------------===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is dual licensed under the MIT and the University of Illinois Open
+# Source Licenses. See LICENSE.TXT for details.
+#
+#===----------------------------------------------------------------------===##
+
+# USAGE: check_experimental_visibility <libcpp-include-dir>
+# This script checks if each header in the given include dir use the correct
+# visibility macros. Experimental headers should use _LIBCPPX macros whereas
+# non-experimental headers should use the regular _LIBCPP macros.
+
+import itertools
+import os
+import sys
+
+visibility_macros = [
+    "HIDDEN",
+    "FUNC_VIS",
+    "EXTERN_VIS",
+    "OVERRIDABLE_FUNC_VIS",
+    "INLINE_VISIBILITY",
+    "ALWAYS_INLINE",
+    "TYPE_VIS",
+    "TEMPLATE_VIS",
+    "ENUM_VIS",
+    "EXTERN_TEMPLATE_TYPE_VIS",
+    "CLASS_TEMPLATE_INSTANTIATION_VIS",
+    "METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS",
+    "EXTERN_TEMPLATE_INLINE_VISIBILITY",
+    "EXCEPTION_ABI",
+]
+
+regular_visibility_macros      = ["_LIBCPP_{}".format(m)  for m in visibility_macros]
+experimental_visibility_macros = ["_LIBCPPX_{}".format(m) for m in visibility_macros]
+
+def main():
+    if len(sys.argv) != 2:
+        sys.stderr.write("Expected only one argument: the libcxx include path\n")
+        return 1
+
+    include_dir = sys.argv[1]
+    if not os.path.isdir(include_dir):
+        sys.stderr.write("Given include path isn't a directory\n")
+        return 1
+
+    # [(rel_file_path, line_number)]
+    invalid_regular_files = []
+    invalid_experimental_files = []
+
+    files_to_check = itertools.chain.from_iterable((
+        ((dir, fname) for fname in filenames if fname != "__config")
+        for (dir, _, filenames) in os.walk(include_dir)
+    ))
+    for (dir, fname) in files_to_check:
+        parent_path = os.path.relpath(dir, include_dir)
+
+        header_path = os.path.join(parent_path, fname) if parent_path != '.' else fname
+        experimental = os.path.split(header_path)[0] == "experimental"
+
+        # List of macros that we shouldn't see in this file.
+        problem_macros = regular_visibility_macros if experimental \
+                         else experimental_visibility_macros
+
+        with open(os.path.join(dir, fname), 'r') as f:
+            problem_lines = (i for (i, line) in enumerate(f, 1)
+                             if any(m in line for m in problem_macros))
+            (invalid_experimental_files if experimental else invalid_regular_files) \
+                .extend((header_path, l) for l in problem_lines)
+
+    if not invalid_regular_files and not invalid_experimental_files:
+        # No problems found
+        return 0
+
+    if invalid_regular_files:
+        sys.stderr.write(
+            "Found usage of experimental visibility macros in non-experimental files.\n"
+            "These should be changed to the corresponding _LIBCPP macros.\n")
+        for (path, line_num) in invalid_regular_files:
+            sys.stderr.write("  <{}>:{:d}\n".format(path, line_num))
+        if invalid_experimental_files:
+            sys.stderr.write("\n\n")
+
+    if invalid_experimental_files:
+        sys.stderr.write(
+            "Found usage of non-experimental visibility macros in experimental files.\n"
+            "These should be changed to the corresponding _LIBCPPX macros\n")
+        for (path, line_num) in invalid_experimental_files:
+            sys.stderr.write("  <{}>:{:d}\n".format(path, line_num))
+
+    return 1
+
+if __name__ == '__main__':
+    sys.exit(main())
+

utils/libcxx/test/config.py

         not_py = os.path.join(self.libcxx_src_root, 'utils', 'not.py')
         not_str = '%s %s ' % (pipes.quote(sys.executable), pipes.quote(not_py))
         sub.append(('not ', not_str))
+        # Configure check_experimental_visibility program substitutions
+        check_experimental_vis_py = os.path.join(self.libcxx_src_root,
+                                                 'utils',
+                                                 'check_experimental_visibility.py')
+        check_experimental_vis_str = '%s %s' % (pipes.quote(sys.executable),
+                                                pipes.quote(check_experimental_vis_py))
+        sub.append(('check_experimental_visibility', check_experimental_vis_str))
 
     def can_use_deployment(self):
         # Check if the host is on an Apple platform using clang.