Automoc: Don't create automoc targets if Qt is not used (#13999)

Commit 79568f95 (automoc: Add source file to target early to set the
linker language, 2013-02-20) changed automoc initialization to a two
step process. In the first step, the generated source file was added
to the target, which allows the link language to be determined.

However, this bypassed the check for the availability of Qt itself.
At build-time the automoc file could not be generated because the moc
tool was not available to create it.

The solution is to only add the automoc file to the target if Qt is
found.

6 files changed, 40 insertions, 15 deletions

diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index f2defbb..2fae7d0 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -1086,8 +1086,10 @@ void cmGlobalGenerator::CreateAutomocTargets()
         if(target.GetPropertyAsBool("AUTOMOC") && !target.IsImported())
           {
           cmQtAutomoc automoc;
-          automoc.InitializeMocSourceFile(&target);
-          automocs.push_back(std::make_pair(automoc, &target));
+          if(automoc.InitializeMocSourceFile(&target))
+            {
+            automocs.push_back(std::make_pair(automoc, &target));
+            }
           }
         }
       }
diff --git a/Source/cmQtAutomoc.cxx b/Source/cmQtAutomoc.cxx
index 10ce641..5730c8c 100644
--- a/Source/cmQtAutomoc.cxx
+++ b/Source/cmQtAutomoc.cxx
@@ -119,10 +119,21 @@ cmQtAutomoc::cmQtAutomoc()
     }
 }
 
-void cmQtAutomoc::InitializeMocSourceFile(cmTarget* target)
+bool cmQtAutomoc::InitializeMocSourceFile(cmTarget* target)
 {
+  cmMakefile* makefile = target->GetMakefile();
+  // don't do anything if there is no Qt4 or Qt5Core (which contains moc):
+  std::string qtMajorVersion = makefile->GetSafeDefinition("QT_VERSION_MAJOR");
+  if (qtMajorVersion == "")
+    {
+    qtMajorVersion = makefile->GetSafeDefinition("Qt5Core_VERSION_MAJOR");
+    }
+  if (qtMajorVersion != "4" && qtMajorVersion != "5")
+    {
+    return false;
+    }
+
   std::string automocTargetName = target->GetName();
-  cmMakefile *makefile = target->GetMakefile();
   automocTargetName += "_automoc";
   std::string mocCppFile = makefile->GetCurrentOutputDirectory();
   mocCppFile += "/";
@@ -134,6 +145,7 @@ void cmQtAutomoc::InitializeMocSourceFile(cmTarget* target)
                            mocCppFile.c_str(), false);
 
   target->AddSourceFile(mocCppSource);
+  return true;
 }
 
 void cmQtAutomoc::SetupAutomocTarget(cmTarget* target)
@@ -141,16 +153,6 @@ void cmQtAutomoc::SetupAutomocTarget(cmTarget* target)
   cmMakefile* makefile = target->GetMakefile();
   cmLocalGenerator* localGen = makefile->GetLocalGenerator();
   const char* targetName = target->GetName();
-  // don't do anything if there is no Qt4 or Qt5Core (which contains moc):
-  std::string qtMajorVersion = makefile->GetSafeDefinition("QT_VERSION_MAJOR");
-  if (qtMajorVersion == "")
-    {
-    qtMajorVersion = makefile->GetSafeDefinition("Qt5Core_VERSION_MAJOR");
-    }
-  if (qtMajorVersion != "4" && qtMajorVersion != "5")
-    {
-    return;
-    }
 
   bool relaxedMode = makefile->IsOn("CMAKE_AUTOMOC_RELAXED_MODE");
 
diff --git a/Source/cmQtAutomoc.h b/Source/cmQtAutomoc.h
index 962e254..01b68fc 100644
--- a/Source/cmQtAutomoc.h
+++ b/Source/cmQtAutomoc.h
@@ -23,7 +23,7 @@ public:
   cmQtAutomoc();
   bool Run(const char* targetDirectory);
 
-  void InitializeMocSourceFile(cmTarget* target);
+  bool InitializeMocSourceFile(cmTarget* target);
   void SetupAutomocTarget(cmTarget* target);
 
 private:
diff --git a/Tests/CMakeLists.txt b/Tests/CMakeLists.txt
index f8e4afd..30f733c 100644
--- a/Tests/CMakeLists.txt
+++ b/Tests/CMakeLists.txt
@@ -970,6 +970,16 @@ ${CMake_BINARY_DIR}/bin/cmake -DVERSION=master -P ${CMake_SOURCE_DIR}/Utilities/
     )
   list(APPEND TEST_BUILD_DIRS "${CMake_BINARY_DIR}/Tests/Environment")
 
+  add_test(QtAutomocNoQt  ${CMAKE_CTEST_COMMAND}
+    --build-and-test
+    "${CMake_SOURCE_DIR}/Tests/QtAutomocNoQt"
+    "${CMake_BINARY_DIR}/Tests/QtAutomocNoQt"
+    ${build_generator_args}
+    --build-project QtAutomocNoQt
+    --build-options -DCMAKE_BUILD_TYPE=\${CTEST_CONFIGURATION_TYPE}
+    )
+  list(APPEND TEST_BUILD_DIRS "${CMake_BINARY_DIR}/Tests/QtAutomocNoQt")
+
   if(QT4_WORKS AND QT_QTGUI_FOUND)
     add_test(QtAutomoc ${CMAKE_CTEST_COMMAND}
       --build-and-test
diff --git a/Tests/QtAutomocNoQt/CMakeLists.txt b/Tests/QtAutomocNoQt/CMakeLists.txt
new file mode 100644
index 0000000..b26e471
--- /dev/null
+++ b/Tests/QtAutomocNoQt/CMakeLists.txt
@@ -0,0 +1,7 @@
+cmake_minimum_required(VERSION 2.8)
+
+project(QtAutomocNoQt)
+
+set(CMAKE_AUTOMOC ON)
+
+add_executable(hello main.c)
diff --git a/Tests/QtAutomocNoQt/main.c b/Tests/QtAutomocNoQt/main.c
new file mode 100644
index 0000000..8488f4e
--- /dev/null
+++ b/Tests/QtAutomocNoQt/main.c
@@ -0,0 +1,4 @@
+int main(void)
+{
+  return 0;
+}