gn build: Give cmake sync script an opt-in --write flag

[pcc]

LGTM

llvm/utils/gn/build/sync_source_lists_from_cmake.py

34

Should this also refuse to operate if it sees a # NOSORT comment? I think the only instance of that is in clang/lib/Headers, though -- maybe we can remove that comment now that we have a mechanism for automatic updates?

[thakis]

Thanks!

llvm/utils/gn/build/sync_source_lists_from_cmake.py

34

Good point. Made this balk on NOSORT for now.

[thakis]

Oh, also gn format honors -q only as of yesterday, before that it ignored the flag silently. Run llvm/utils/gn/get.py to download a new gn binary that supports it if you find the "Wrote formatted...." output from gn annoying.

llvm/utils/gn/build/sync_source_lists_from_cmake.py

 #!/usr/bin/env python
 
 """Helps to keep BUILD.gn files in sync with the corresponding CMakeLists.txt.
 
 For each BUILD.gn file in the tree, checks if the list of cpp files in
 it is identical to the list of cpp files in the corresponding CMakeLists.txt
 file, and prints the difference if not.
 
 Also checks that each CMakeLists.txt file below unittests/ folders that define
 binaries have corresponding BUILD.gn files.
+
+If --write is passed, tries to write modified .gn files and adds one git
+commit for each cmake commit this merges. If an error is reported, the state
+of HEAD is unspecified; run `git reset --hard origin/master` if this happens.
 """
 
 from __future__ import print_function
 
 from collections import defaultdict
 import os
 import re
 import subprocess
 import sys
 
 
-def sync_source_lists():
+def patch_gn_file(gn_file, add, remove):
+    with open(gn_file) as f:
+      gn_contents = f.read()
+
+    srcs_tok = 'sources = ['
+    tokloc = gn_contents.find(srcs_tok)
+
+    if tokloc == -1: raise ValueError(gn_file + ': Failed to find source list')
+    if gn_contents.find(srcs_tok, tokloc + 1) != -1:
+        raise ValueError(gn_file + ': Multiple source lists')
+
+    tokloc += len(srcs_tok)
+    for a in add:
+        gn_contents = (gn_contents[:tokloc] + ('"%s",' % a) +
+                       gn_contents[tokloc:])
+    for r in remove:
+        gn_contents = gn_contents.replace('"%s",' % r, '')
+    with open(gn_file, 'w') as f:
+      f.write(gn_contents)
+
+    # Run `gn format`.
+    gn = os.path.join(os.path.dirname(__file__), '..', 'gn.py')
+    subprocess.check_call([sys.executable, gn, 'format', '-q', gn_file])
+
+
+def sync_source_lists(write):
     # Use shell=True on Windows in case git is a bat file.
+    git_want_shell = os.name == 'nt'
     gn_files = subprocess.check_output(['git', 'ls-files', '*BUILD.gn'],
-                                       shell=os.name == 'nt').splitlines()
+                                       shell=git_want_shell).splitlines()
 
     # Matches e.g. |   "foo.cpp",|, captures |foo| in group 1.
     gn_cpp_re = re.compile(r'^\s*"([^"]+\.(?:cpp|c|h|S))",$', re.MULTILINE)
     # Matches e.g. |   foo.cpp|, captures |foo| in group 1.
     cmake_cpp_re = re.compile(r'^\s*([A-Za-z_0-9./-]+\.(?:cpp|c|h|S))$',
                               re.MULTILINE)
 
     changes_by_rev = defaultdict(lambda: defaultdict(lambda: defaultdict(list)))
 
     def find_gitrev(touched_line, in_file):
         return subprocess.check_output(
             ['git', 'log', '--format=%h', '-1', '-S' + touched_line, in_file],
-            shell=os.name == 'nt').rstrip()
+            shell=git_want_shell).rstrip()
     def svnrev_from_gitrev(gitrev):
         git_llvm = os.path.join(
             os.path.dirname(__file__), '..', '..', 'git-svn', 'git-llvm')
         return int(subprocess.check_output(
             [sys.executable, git_llvm, 'svn-lookup', gitrev],
-            shell=os.name == 'nt').rstrip().lstrip('r'))
+            ).rstrip().lstrip('r'))
 
     # Collect changes to gn files, grouped by revision.
     for gn_file in gn_files:
         # The CMakeLists.txt for llvm/utils/gn/secondary/foo/BUILD.gn is
         # at foo/CMakeLists.txt.
         strip_prefix = 'llvm/utils/gn/secondary/'
         if not gn_file.startswith(strip_prefix):
             continue
for gn_file in gn_files:
         def by_rev(files, key):
             for f in files:
                 svnrev = svnrev_from_gitrev(find_gitrev(f, cmake_file))
                 changes_by_rev[svnrev][gn_file][key].append(f)
         by_rev(sorted(cmake_cpp - gn_cpp), 'add')
         by_rev(sorted(gn_cpp - cmake_cpp), 'remove')
 
     # Output necessary changes grouped by revision.
-    for svnrev in sorted(changes_by_rev.keys()):
+    for svnrev in sorted(changes_by_rev):
         print('gn build: Merge r{0} -- https://reviews.llvm.org/rL{0}'
             .format(svnrev))
         for gn_file, data in sorted(changes_by_rev[svnrev].items()):
+            add = data.get('add', [])
+            remove = data.get('remove', [])
+            if write:
+                patch_gn_file(gn_file, add, remove)
+                subprocess.check_call(['git', 'add', gn_file],
+                                      shell=git_want_shell)
+            else:
                 print('  ' + gn_file)
-            add = data.get('add')
                 if add:
-                print('    add:\n' + '\n'.join('    "%s",' % a for a in add))
-            remove = data.get('remove')
+                    print('   add:\n' + '\n'.join('    "%s",' % a for a in add))
                 if remove:
-                print('    remove:\n    ' + '\n    '.join(remove))
+                    print('   remove:\n    ' + '\n    '.join(remove))
                 print()
+        if write:
+            subprocess.check_call(
+                ['git', 'commit', '-m', 'gn build: Merge r%d' % svnrev],
+                shell=git_want_shell)
+        else:
             print()
 
     return bool(changes_by_rev)
 
 
 def sync_unittests():
     # Matches e.g. |add_llvm_unittest_with_input_files|.
     unittest_re = re.compile(r'^add_\S+_unittest', re.MULTILINE)
 
for c in checked:
             if not os.path.exists(gn_file):
                 changed = True
                 print('missing GN file %s for unittest CMake file %s' %
                       (gn_file, cmake_file))
     return changed
 
 
 def main():
-    src = sync_source_lists()
+    src = sync_source_lists(len(sys.argv) > 1 and sys.argv[1] == '--write')
     tests = sync_unittests()
     if src or tests:
         sys.exit(1)
 
 
 
 if __name__ == '__main__':
     main()