Add support for QT_GN_VERSION

Change-Id: If5ac705f3a4292da915d1f36526ef1fbed3868e6
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

2 files changed, 24 insertions, 2 deletions

diff --git a/gn/build/gen.py b/gn/build/gen.py
index 724d94c45c1..38d4ec253f4 100755
--- a/gn/build/gen.py
+++ b/gn/build/gen.py
@@ -139,6 +139,8 @@ def main(argv):
                     help='The path to ar.')
   parser.add_option('--isysroot',
                     help='The path to the macOS SDK sysroot to be used.')
+  parser.add_option('--qt-version',
+                    help="The qt version gn is compiled for.")
   options, args = parser.parse_args(argv)
 
   if args:
@@ -156,6 +158,9 @@ def main(argv):
   if not options.no_last_commit_position:
     GenerateLastCommitPosition(host,
                                os.path.join(out_dir, 'last_commit_position.h'))
+  if options.qt_version:
+      generate_qt_version_header(options.qt_version, os.path.join(out_dir, 'qt_version.h'))
+
   WriteGNNinja(os.path.join(out_dir, 'build.ninja'), platform, host, options)
   return 0
 
@@ -843,5 +848,22 @@ def windows_target_build_arch():
     if platform.machine().lower() in ['x86_64', 'amd64']: return 'x64'
     return 'x86'
 
+def generate_qt_version_header(qtVersion,header):
+  contents = '''// Generated by build/gen.py.
+
+#ifndef QT_GN_VERSION
+#define QT_GN_VERSION "%s"
+#endif
+''' % (qtVersion)
+
+  old_contents = ''
+  if os.path.isfile(header):
+    with open(header, 'r') as f:
+      old_contents = f.read()
+
+  if old_contents != contents:
+    with open(header, 'w') as f:
+      f.write(contents)
+
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))
diff --git a/gn/src/gn/gn_main.cc b/gn/src/gn/gn_main.cc
index 3d260a3c46f..ae54a2aecfd 100644
--- a/gn/src/gn/gn_main.cc
+++ b/gn/src/gn/gn_main.cc
@@ -16,7 +16,7 @@
 #include "util/msg_loop.h"
 #include "util/sys_info.h"
 
-// #include "last_commit_position.h"
+#include "qt_version.h"
 
 namespace {
 
@@ -49,7 +49,7 @@ int main(int argc, char** argv) {
     command = commands::kHelp;
   } else if (cmdline.HasSwitch(switches::kVersion)) {
     // Make "--version" print the version and exit.
-//     OutputString(std::string(LAST_COMMIT_POSITION) + "\n");
+    OutputString(std::string(QT_GN_VERSION) +"\n");
     exit(0);
   } else if (args.empty()) {
     // No command, print error and exit.