New build flag system, convert Google Now flag
This generates headers with build flags rather than forcing them all to be global. It includes an accessor wrapper so that references to the flags will fail if the proper header is not included.
Converts Google Now to use this and remove the global google now define and grit define.
Adds support for grit define values of "true" and "false" for ease of integration with GN (they are mapped to the corresponding Python "True" and "False").
Adds dependencies from the main gyp targets to the new generated feature define target. Since GYP only does hard dependencies one level, this should reduce the chance that somebody adds more of these cases and forces to add a dependency.
Reland of https://codereview.chromium.org/1475513006/
Reland of https://codereview.chromium.org/1458653002/
TBR=mark@chromium.org
Review URL: https://codereview.chromium.org/1469383005
Cr-Commit-Position: refs/heads/master@{#361854}
CrOS-Libchrome-Original-Commit: 06c2ba3165d8b02364bf818d5028a7cb4fe48ac0
diff --git a/build/buildflag.h b/build/buildflag.h
new file mode 100644
index 0000000..283f5bc
--- /dev/null
+++ b/build/buildflag.h
@@ -0,0 +1,47 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BUILD_BUILDFLAG_H_
+#define BUILD_BUILDFLAG_H_
+
+// These macros un-mangle the names of the build flags in a way that looks
+// natural, and gives errors if the flag is not defined. Normally in the
+// preprocessor it's easy to make mistakes that interpret "you haven't done
+// the setup to know what the flag is" as "flag is off". Normally you would
+// include the generated header rather than include this file directly.
+//
+// This is for use with generated headers. See build/build_header.gni.
+
+// This dance of two macros does a concatenation of two preprocessor args using
+// ## doubly indirectly because using ## directly prevents macros in that
+// parameter from being expanded.
+#define BUILDFLAG_CAT_INDIRECT(a, b) a ## b
+#define BUILDFLAG_CAT(a, b) BUILDFLAG_CAT_INDIRECT(a, b)
+
+// Accessor for build flags.
+//
+// To test for a value, if the build file specifies:
+//
+// ENABLE_FOO=true
+//
+// Then you would check at build-time in source code with:
+//
+// #include "foo_flags.h" // The header the build file specified.
+//
+// #if BUILDFLAG(ENABLE_FOO)
+// ...
+// #endif
+//
+// There will no #define called ENABLE_FOO so if you accidentally test for
+// whether that is defined, it will always be negative. You can also use
+// the value in expressions:
+//
+// const char kSpamServerName[] = BUILDFLAG(SPAM_SERVER_NAME);
+//
+// Because the flag is accessed as a preprocessor macro with (), an error
+// will be thrown if the proper header defining the internal flag value has
+// not been included.
+#define BUILDFLAG(flag) (BUILDFLAG_CAT(BUILDFLAG_INTERNAL_, flag)())
+
+#endif // BUILD_BUILDFLAG_H_
diff --git a/build/gypi_to_gn.py b/build/gypi_to_gn.py
index a107f94..6de1a63 100644
--- a/build/gypi_to_gn.py
+++ b/build/gypi_to_gn.py
@@ -96,10 +96,12 @@
if 'target_conditions' in file_data:
del file_data['target_conditions']
- # Strip targets in the toplevel, since some files define these and we can't
- # slurp them in.
+ # Strip targets and includes in the toplevel, since some files define these
+ # and we can't slurp them in.
if 'targets' in file_data:
del file_data['targets']
+ if 'includes' in file_data:
+ del file_data['includes']
return file_data
diff --git a/build/write_buildflag_header.py b/build/write_buildflag_header.py
new file mode 100755
index 0000000..d46cfc8
--- /dev/null
+++ b/build/write_buildflag_header.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# This writes headers for build flags. See buildflag_header.gni for usage of
+# this system as a whole.
+#
+# The parameters are passed in a response file so we don't have to worry
+# about command line lengths. The name of the response file is passed on the
+# command line.
+#
+# The format of the response file is:
+# [--flags <list of one or more flag values>]
+
+import optparse
+import os
+import shlex
+import sys
+
+
+class Options:
+ def __init__(self, output, rulename, header_guard, flags):
+ self.output = output
+ self.rulename = rulename
+ self.header_guard = header_guard
+ self.flags = flags
+
+
+def GetOptions():
+ parser = optparse.OptionParser()
+ parser.add_option('--output', help="Output header name inside --gen-dir.")
+ parser.add_option('--rulename',
+ help="Helpful name of build rule for including in the " +
+ "comment at the top of the file.")
+ parser.add_option('--gen-dir',
+ help="Path to root of generated file directory tree.")
+ parser.add_option('--definitions',
+ help="Name of the response file containing the flags.")
+ cmdline_options, cmdline_flags = parser.parse_args()
+
+ # Compute header guard by replacing some chars with _ and upper-casing.
+ header_guard = cmdline_options.output.upper()
+ header_guard = \
+ header_guard.replace('/', '_').replace('\\', '_').replace('.', '_')
+ header_guard += '_'
+
+ # The actual output file is inside the gen dir.
+ output = os.path.join(cmdline_options.gen_dir, cmdline_options.output)
+
+ # Definition file in GYP is newline separated, in GN they are shell formatted.
+ # shlex can parse both of these.
+ with open(cmdline_options.definitions, 'r') as def_file:
+ defs = shlex.split(def_file.read())
+ flags_index = defs.index('--flags')
+
+ # Everything after --flags are flags. true/false are remapped to 1/0,
+ # everything else is passed through.
+ flags = []
+ for flag in defs[flags_index + 1 :]:
+ equals_index = flag.index('=')
+ key = flag[:equals_index]
+ value = flag[equals_index + 1:]
+
+ # Canonicalize and validate the value.
+ if value == 'true':
+ value = '1'
+ elif value == 'false':
+ value = '0'
+ flags.append((key, str(value)))
+
+ return Options(output=output,
+ rulename=cmdline_options.rulename,
+ header_guard=header_guard,
+ flags=flags)
+
+
+def WriteHeader(options):
+ with open(options.output, 'w') as output_file:
+ output_file.write("// Generated by build/write_buildflag_header.py\n")
+ if options.rulename:
+ output_file.write('// From "' + options.rulename + '"\n')
+
+ output_file.write('\n#ifndef %s\n' % options.header_guard)
+ output_file.write('#define %s\n\n' % options.header_guard)
+ output_file.write('#include "build/buildflag.h"\n\n')
+
+ for pair in options.flags:
+ output_file.write('#define BUILDFLAG_INTERNAL_%s() (%s)\n' % pair)
+
+ output_file.write('\n#endif // %s\n' % options.header_guard)
+
+
+options = GetOptions()
+WriteHeader(options)