Linux: use generated shim headers for system mesa.

ui/gl/generate_bindings.py

Index: ui/gl/generate_bindings.py
diff --git a/ui/gl/generate_bindings.py b/ui/gl/generate_bindings.py
index f90797c26d7e175ec95407c376a4a28536a066e5..96e297d345d9744f89fffbda01a4b4819c05bb41 100755
--- a/ui/gl/generate_bindings.py
+++ b/ui/gl/generate_bindings.py
@@ -5,6 +5,7 @@
 
 """code generator for GL/GLES extension wrangler."""
 
+import optparse
 import os
 import collections
 import re
@@ -1140,21 +1141,32 @@ GLX_FUNCTIONS = [
       'int32* denominator' },
 ]
 
+BUNDLED_HEADER_PATHS = [
+    '../../third_party/mesa/MesaLib/include',
+    '../../third_party/khronos',
+]
+
+SYSTEM_HEADER_PATHS = [
+    '/usr/include',
+]
+
 FUNCTION_SETS = [
-  [GL_FUNCTIONS, 'gl', ['../../third_party/mesa/MesaLib/include/GL/glext.h',
-    '../../third_party/khronos/GLES2/gl2ext.h'], []],
+  [GL_FUNCTIONS, 'gl', [
+      'GL/glext.h',
+      'GLES2/gl2ext.h',
+      # Files below are Chromium-specific and shipped with Chromium sources.
+      'GLES2/gl2chromium.h',
+      'GLES2/gl2extchromium.h'
+  ], []],
   [OSMESA_FUNCTIONS, 'osmesa', [], []],
-  [EGL_FUNCTIONS, 'egl', ['../../third_party/khronos/EGL/eglext.h'],
+  [EGL_FUNCTIONS, 'egl', ['EGL/eglext.h'],
     [
       'EGL_ANGLE_d3d_share_handle_client_buffer',
       'EGL_ANGLE_surface_d3d_texture_2d_share_handle',
     ],
   ],
-  [WGL_FUNCTIONS, 'wgl', [
-    '../../third_party/mesa/MesaLib/include/GL/wglext.h'], []],
-  [GLX_FUNCTIONS, 'glx', [
-    '../../third_party/mesa/MesaLib/include/GL/glx.h',
-    '../../third_party/mesa/MesaLib/include/GL/glxext.h'], []],
+  [WGL_FUNCTIONS, 'wgl', ['GL/wglext.h'], []],
+  [GLX_FUNCTIONS, 'glx', ['GL/glx.h', 'GL/glxext.h'], []],
 ]
 
 def GenerateHeader(file, functions, set_name, used_extension_functions):
@@ -1585,7 +1597,7 @@ def ParseExtensionFunctionsFromHeader(header_file):
     Map of extension name => functions.
   """
   extension_start = re.compile(r'#define ([A-Z]+_[A-Z]+_[a-zA-Z]\w+) 1')
-  extension_function = re.compile(r'.+\s+([a-z]+\w+)\s*\(.+\);')
+  extension_function = re.compile(r'.+\s+([a-z]+\w+)\s*\(')
   typedef = re.compile(r'typedef .*')
   macro_start = re.compile(r'^#(if|ifdef|ifndef).*')
   macro_end = re.compile(r'^#endif.*')
@@ -1696,15 +1708,51 @@ def GetUsedExtensionFunctions(functions, extension_headers, extra_extensions):
   return used_extension_functions
 
 
+def ResolveHeader(header, use_system_mesa):

[greggman, 2013/01/07 20:23:33]

All the changes in this file seem like adding a burden to every other platform
just so Linux and use system headers.

Is there a way to make this work without editing this file?

[Paweł Hajdan Jr., 2013/01/07 21:20:05]

No. This file is executed during the build process, and would otherwise refer to
the bundled headers instead of system headers (and the bundled headers may not
even exist at that time since they can be removed to ensure they are not used).

There might be some other approach to be used in modifying this file though. I'm
open to suggestions.

Note that such burden is often overestimated by people, seriously. You do not
need to test or support the use_system code paths. I do understand the concerns
about that though.

[greggman, 2013/01/07 21:32:22]

It's not just a burden. The code you added is the only code in that entire file
that's platform specific. In order to edit that file I have to understand what
it's doing. I shouldn't need to understand anything about use_system_mesa. the
word shouldn't even appear in this file.

One suggestion would be to find a way to remove the "../../third_party/khronos"
and "../third_party/mesa" from this file and update gl.gyp so it still compiles
and uses stuff from third_party/khronos and third_party/mesa by having the
correct include paths.

Then. In, in a separate CL, update gl.gyp so it can instead go through your shim
for the system mesa

How's that sound?

+  if use_system_mesa == 1:
+    paths = SYSTEM_HEADER_PATHS
+  else:
+    paths = BUNDLED_HEADER_PATHS
+
+  # Always use a path for Chromium-specific extensions. They are extracted
+  # to separate files.
+  paths.append('../../gpu')
+
+  root = os.path.abspath(os.path.dirname(__file__))
+
+  for path in paths:
+    result = os.path.join(path, header)
+    if not os.path.isabs(path):
+      result = os.path.relpath(os.path.join(root, result), os.getcwd())
+    if os.path.exists(result):
+      return result
+
+  raise Exception('Header %s not found.' % header)
+
+
 def main(argv):
   """This is the main function."""
 
-  if len(argv) >= 1:
-    dir = argv[0]
+  parser = optparse.OptionParser()
+  parser.add_option('--inputs', action='store_true')
+  parser.add_option('--use-system-mesa', type=int, default=0)
+
+  options, args = parser.parse_args(argv)
+
+  if options.inputs:
+    for [_, _, headers, _] in FUNCTION_SETS:
+      for header in headers:
+        print ResolveHeader(header, options.use_system_mesa)
+    return 0
+
+  if len(args) >= 1:
+    dir = args[0]
   else:
     dir = '.'
 
   for [functions, set_name, extension_headers, extensions] in FUNCTION_SETS:
+    extension_headers = [ResolveHeader(h, options.use_system_mesa)
+                         for h in extension_headers]
     used_extension_functions = GetUsedExtensionFunctions(
         functions, extension_headers, extensions)