From a223a3b65f518f59a73967f0087b0d67842d9f0d Mon Sep 17 00:00:00 2001
From: Stephen Kelly <steveire@gmail.com>
Date: Mon, 11 Mar 2013 23:26:38 +0100
Subject: [PATCH] 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.
---
 Source/cmGlobalGenerator.cxx       |  6 ++++--
 Source/cmQtAutomoc.cxx             | 26 ++++++++++++++------------
 Source/cmQtAutomoc.h               |  2 +-
 Tests/CMakeLists.txt               | 10 ++++++++++
 Tests/QtAutomocNoQt/CMakeLists.txt |  7 +++++++
 Tests/QtAutomocNoQt/main.c         |  4 ++++
 6 files changed, 40 insertions(+), 15 deletions(-)
 create mode 100644 Tests/QtAutomocNoQt/CMakeLists.txt
 create mode 100644 Tests/QtAutomocNoQt/main.c

diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index f2defbb4d..2fae7d05b 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 10ce6416d..5730c8c9d 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 962e25496..01b68fc54 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 f8e4afd62..30f733cb6 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 000000000..b26e47117
--- /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 000000000..8488f4e58
--- /dev/null
+++ b/Tests/QtAutomocNoQt/main.c
@@ -0,0 +1,4 @@
+int main(void)
+{
+  return 0;
+}