Add support for generating the QtCreator projects from GN.

tools/gn/command_gen.cc

Index: tools/gn/command_gen.cc
diff --git a/tools/gn/command_gen.cc b/tools/gn/command_gen.cc
index 74a5d90cfd3495b0530a6e679796b53b62b431a1..670a0c65ea49820c4db513ea3b9d77a74b8b9193 100644
--- a/tools/gn/command_gen.cc
+++ b/tools/gn/command_gen.cc
@@ -13,6 +13,7 @@
 #include "tools/gn/eclipse_writer.h"
 #include "tools/gn/ninja_target_writer.h"
 #include "tools/gn/ninja_writer.h"
+#include "tools/gn/qt_creator_writer.h"
 #include "tools/gn/runtime_deps.h"
 #include "tools/gn/scheduler.h"
 #include "tools/gn/setup.h"
@@ -30,6 +31,7 @@ const char kSwitchCheck[] = "check";
 const char kSwitchFilters[] = "filters";
 const char kSwitchIde[] = "ide";
 const char kSwitchIdeValueEclipse[] = "eclipse";
+const char kSwitchIdeValueQtCreator[] = "qtcreator";
 const char kSwitchIdeValueVs[] = "vs";
 const char kSwitchIdeValueVs2013[] = "vs2013";
 const char kSwitchIdeValueVs2015[] = "vs2015";
@@ -206,6 +208,18 @@ bool RunIdeWriter(const std::string& ide,
                    "ms\n");
     }
     return res;
+  } else if (ide == kSwitchIdeValueQtCreator) {
+    std::string root_target;
+    if (command_line->HasSwitch(kSwitchRootTarget))
+      root_target = command_line->GetSwitchValueASCII(kSwitchRootTarget);
+    bool res = QtCreatorWriter::RunAndWriteFile(build_settings, builder, err,
+                                                root_target);
+    if (res && !command_line->HasSwitch(switches::kQuiet)) {
+      OutputString("Generating QtCreator projects took " +
+                   base::Int64ToString(timer.Elapsed().InMilliseconds()) +
+                   "ms\n");
+    }
+    return res;
   }
 
   *err = Err(Location(), "Unknown IDE: " + ide);
@@ -244,6 +258,7 @@ const char kGen_Help[] =
     "      \"vs2013\" - Visual Studio 2013 project/solution files.\n"
     "      \"vs2015\" - Visual Studio 2015 project/solution files.\n"
     "      \"xcode\" - Xcode workspace/solution files.\n"
+    "      \"qtcreator\" - QtCreator project files.\n"
     "\n"
     "  --filters=<path_prefixes>\n"
     "      Semicolon-separated list of label patterns used to limit the set\n"
@@ -269,9 +284,9 @@ const char kGen_Help[] =
     "      using goma for example.\n"
     "\n"
     "  --root-target=<target_name>\n"
-    "      Name of the target corresponding to \"All\" target in Xcode. If\n"
-    "      unset, \"All\" invokes ninja without any target thus build all the\n"
-    "      targets.\n"
+    "      Name of the target corresponding to \"All\" target in Xcode\n"

[Dirk Pranke, 2016/05/13 01:50:23]

You didn't create a separate "QtCreator Flags" section like I suggested. LGTM if
you do that as well (I'm assuming you just forgot), but if you think that's the
wrong thing to do, I'd like to know your thoughts.

[Krzysztof Olczyk, 2016/05/13 10:32:14]

Yes, I totally agree. I apologize - somehow, I haven't read the initial part of
your comment.
Done now.

+    "      or QtCreator. If unset, \"All\" invokes ninja without any target\n"
+    "      and builds everything.\n"
     "\n"
     "Eclipse IDE Support\n"
     "\n"