1# Copyright 2015 the V8 project authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5# Autocompletion config for YouCompleteMe in V8.
6#
7# USAGE:
8#
9#   1. Install YCM [https://github.com/Valloric/YouCompleteMe]
10#          (Googlers should check out [go/ycm])
11#
12#   2. Profit
13#
14#
15# Usage notes:
16#
17#   * You must use ninja & clang to build V8.
18#
19#   * You must have run gyp_v8 and built V8 recently.
20#
21#
22# Hacking notes:
23#
24#   * The purpose of this script is to construct an accurate enough command line
25#     for YCM to pass to clang so it can build and extract the symbols.
26#
27#   * Right now, we only pull the -I and -D flags. That seems to be sufficient
28#     for everything I've used it for.
29#
30#   * That whole ninja & clang thing? We could support other configs if someone
31#     were willing to write the correct commands and a parser.
32#
33#   * This has only been tested on gTrusty.
34
35
36import os
37import os.path
38import subprocess
39import sys
40
41
42# Flags from YCM's default config.
43flags = [
44'-DUSE_CLANG_COMPLETER',
45'-std=gnu++11',
46'-x',
47'c++',
48]
49
50
51def PathExists(*args):
52  return os.path.exists(os.path.join(*args))
53
54
55def FindV8SrcFromFilename(filename):
56  """Searches for the root of the V8 checkout.
57
58  Simply checks parent directories until it finds .gclient and v8/.
59
60  Args:
61    filename: (String) Path to source file being edited.
62
63  Returns:
64    (String) Path of 'v8/', or None if unable to find.
65  """
66  curdir = os.path.normpath(os.path.dirname(filename))
67  while not (PathExists(curdir, 'v8') and PathExists(curdir, 'v8', 'DEPS')
68             and (PathExists(curdir, '.gclient')
69                  or PathExists(curdir, 'v8', '.git'))):
70    nextdir = os.path.normpath(os.path.join(curdir, '..'))
71    if nextdir == curdir:
72      return None
73    curdir = nextdir
74  return os.path.join(curdir, 'v8')
75
76
77def GetClangCommandFromNinjaForFilename(v8_root, filename):
78  """Returns the command line to build |filename|.
79
80  Asks ninja how it would build the source file. If the specified file is a
81  header, tries to find its companion source file first.
82
83  Args:
84    v8_root: (String) Path to v8/.
85    filename: (String) Path to source file being edited.
86
87  Returns:
88    (List of Strings) Command line arguments for clang.
89  """
90  if not v8_root:
91    return []
92
93  # Generally, everyone benefits from including V8's root, because all of
94  # V8's includes are relative to that.
95  v8_flags = ['-I' + os.path.join(v8_root)]
96
97  # Version of Clang used to compile V8 can be newer then version of
98  # libclang that YCM uses for completion. So it's possible that YCM's libclang
99  # doesn't know about some used warning options, which causes compilation
100  # warnings (and errors, because of '-Werror');
101  v8_flags.append('-Wno-unknown-warning-option')
102
103  # Header files can't be built. Instead, try to match a header file to its
104  # corresponding source file.
105  if filename.endswith('.h'):
106    alternates = ['.cc', '.cpp']
107    for alt_extension in alternates:
108      alt_name = filename[:-2] + alt_extension
109      if os.path.exists(alt_name):
110        filename = alt_name
111        break
112    else:
113      if filename.endswith('-inl.h'):
114        for alt_extension in alternates:
115          alt_name = filename[:-6] + alt_extension
116          if os.path.exists(alt_name):
117            filename = alt_name
118            break;
119        else:
120          # If this is a standalone -inl.h file with no source, the best we can
121          # do is try to use the default flags.
122          return v8_flags
123      else:
124        # If this is a standalone .h file with no source, the best we can do is
125        # try to use the default flags.
126        return v8_flags
127
128  sys.path.append(os.path.join(v8_root, 'tools', 'ninja'))
129  from ninja_output import GetNinjaOutputDirectory
130  out_dir = os.path.realpath(GetNinjaOutputDirectory(v8_root))
131
132  # Ninja needs the path to the source file relative to the output build
133  # directory.
134  rel_filename = os.path.relpath(os.path.realpath(filename), out_dir)
135
136  # Ask ninja how it would build our source file.
137  p = subprocess.Popen(['ninja', '-v', '-C', out_dir, '-t',
138                        'commands', rel_filename + '^'],
139                       stdout=subprocess.PIPE)
140  stdout, stderr = p.communicate()
141  if p.returncode:
142    return v8_flags
143
144  # Ninja might execute several commands to build something. We want the last
145  # clang command.
146  clang_line = None
147  for line in reversed(stdout.split('\n')):
148    if 'clang' in line:
149      clang_line = line
150      break
151  else:
152    return v8_flags
153
154  # Parse flags that are important for YCM's purposes.
155  for flag in clang_line.split(' '):
156    if flag.startswith('-I'):
157      # Relative paths need to be resolved, because they're relative to the
158      # output dir, not the source.
159      if flag[2] == '/':
160        v8_flags.append(flag)
161      else:
162        abs_path = os.path.normpath(os.path.join(out_dir, flag[2:]))
163        v8_flags.append('-I' + abs_path)
164    elif flag.startswith('-std'):
165      v8_flags.append(flag)
166    elif flag.startswith('-') and flag[1] in 'DWFfmO':
167      if flag == '-Wno-deprecated-register' or flag == '-Wno-header-guard':
168        # These flags causes libclang (3.3) to crash. Remove it until things
169        # are fixed.
170        continue
171      v8_flags.append(flag)
172
173  return v8_flags
174
175
176def FlagsForFile(filename):
177  """This is the main entry point for YCM. Its interface is fixed.
178
179  Args:
180    filename: (String) Path to source file being edited.
181
182  Returns:
183    (Dictionary)
184      'flags': (List of Strings) Command line flags.
185      'do_cache': (Boolean) True if the result should be cached.
186  """
187  v8_root = FindV8SrcFromFilename(filename)
188  v8_flags = GetClangCommandFromNinjaForFilename(v8_root, filename)
189  final_flags = flags + v8_flags
190  return {
191    'flags': final_flags,
192    'do_cache': True
193  }
194