AutoGen: Use depfiles for the XXX_autogen ninja targets

The XXX_autogen targets are implemented as utility commands, which
means they always run, even if there weren't any changes.

For the Ninja generator and Qt >= 5.15 we're taking a different
approach: This commit adds custom commands that create
XXX_autogen/timestamp files. Those custom commands have a depfile
assigned that is generated from the depfiles that were created by moc.

The XXX_autogen targets merely wrap the XXX_autogen/timestamp custom
commands.

Fixes: #18749

1 files changed, 2 insertions, 0 deletions

diff --git a/Source/cmQtAutoGenInitializer.h b/Source/cmQtAutoGenInitializer.h
index 8cedf14..48ec1a0 100644
--- a/Source/cmQtAutoGenInitializer.h
+++ b/Source/cmQtAutoGenInitializer.h
@@ -191,6 +191,8 @@ private:
     bool DependOrigin = false;
     std::set<std::string> DependFiles;
     std::set<cmTarget*> DependTargets;
+    std::string DepFile;
+    std::string DepFileRuleName;
     // Sources to process
     std::unordered_map<cmSourceFile*, MUFileHandle> Headers;
     std::unordered_map<cmSourceFile*, MUFileHandle> Sources;