AUTOMOC: Skip PCH when all sources files skip the PCH file too

Fixes: #23464

2 files changed, 33 insertions, 0 deletions

diff --git a/Tests/RunCMake/Ninja/QtAutoMocSkipPch.cmake b/Tests/RunCMake/Ninja/QtAutoMocSkipPch.cmake
new file mode 100644
index 0000000..059b917
--- /dev/null
+++ b/Tests/RunCMake/Ninja/QtAutoMocSkipPch.cmake
@@ -0,0 +1,17 @@
+enable_language(CXX)
+
+set(QtX Qt${with_qt_version})
+
+find_package(${QtX} REQUIRED COMPONENTS Core)
+
+set(CMAKE_AUTOMOC ON)
+
+add_library(simple_lib SHARED simple_lib.cpp)
+add_executable(app_with_qt app.cpp app_qt.cpp)
+
+target_link_libraries(app_with_qt PRIVATE simple_lib ${QtX}::Core)
+
+set_source_files_properties(app.cpp app_qt.cpp
+    PROPERTIES SKIP_PRECOMPILE_HEADERS ON)
+
+target_precompile_headers(app_with_qt PRIVATE [["QObject"]])
diff --git a/Tests/RunCMake/Ninja/RunCMakeTest.cmake b/Tests/RunCMake/Ninja/RunCMakeTest.cmake
index 2a5b556..9f078e6 100644
--- a/Tests/RunCMake/Ninja/RunCMakeTest.cmake
+++ b/Tests/RunCMake/Ninja/RunCMakeTest.cmake
@@ -357,6 +357,22 @@ function(run_QtAutoMocDeps)
     run_ninja("${RunCMake_TEST_BINARY_DIR}")
   endif()
 endfunction()
+
+function(run_QtAutoMocSkipPch)
+  set(QtX Qt${CMake_TEST_Qt_version})
+  if(CMake_TEST_${QtX}Core_Version VERSION_GREATER_EQUAL 5.15.0)
+    set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/QtAutoMocSkipPch-build)
+    run_cmake_with_options(QtAutoMocSkipPch
+      "-Dwith_qt_version=${CMake_TEST_Qt_version}"
+      "-D${QtX}_DIR=${${QtX}_DIR}"
+      "-D${QtX}Core_DIR=${${QtX}Core_DIR}"
+      "-DCMAKE_PREFIX_PATH:STRING=${CMAKE_PREFIX_PATH}"
+    )
+    # Build the project.
+    run_ninja("${RunCMake_TEST_BINARY_DIR}")
+  endif()
+endfunction()
 if(CMake_TEST_Qt_version)
   run_QtAutoMocDeps()
+  run_QtAutoMocSkipPch()
 endif()