Add initial support for CMake "Ninja Multi-Config" generator

This allows doing debug_and_release builds with Ninja on all
platforms.
The "Ninja Multi-Config generator" is available starting with CMake
3.17.

Desired configurations can be set via CMAKE_CONFIGURATION_TYPES.
Possible values: "Release, Debug, RelWithDebInfo, MinRelSize".
For example -DCMAKE_CONFIGURATION_TYPES="Release;Debug".

The first configuration is the 'default' configuration which is
built when calling ninja with no arguments.

To build all targets of a certain configuration use "ninja all:Release"
or "ninja all:Debug".

To build all targets in all configurations use "ninja all:all".

Note that the first configuration influences which configuration of
tools will be used when building the libraries for all configurations.
In simple terms, when configured with
-DCMAKE_CONFIGURATION_TYPES="Release;Debug" the release version of moc
is used by AUTOMOC.
When configured with -DCMAKE_CONFIGURATION_TYPES="Debug;Release"
the debug version of moc is used by AUTOMOC.

Framework builds and Ninja Multi-Config don't currently work together
due to multiple bugs in CMake, which ends up generating an invalid ninja
file with duplicate rules. There are also issues with placement of the
debug artifacts.

This will be handled in a follow up patch after CMake is fixed.

Task-number: QTBUG-76899
Change-Id: If224adc0b71b7d1d6606738101536146aa866cd7
Reviewed-by: Qt CMake Build Bot
Reviewed-by: Leander Beernaert <leander.beernaert@qt.io>
Reviewed-by: Cristian Adam <cristian.adam@qt.io>

1 files changed, 11 insertions, 1 deletions

diff --git a/src/tools/cmake_automoc_parser/main.cpp b/src/tools/cmake_automoc_parser/main.cpp
index 456b06b072..60eb4b2977 100644
--- a/src/tools/cmake_automoc_parser/main.cpp
+++ b/src/tools/cmake_automoc_parser/main.cpp
@@ -264,6 +264,12 @@ int main(int argc, char **argv)
     cmakeAutogenIncludeDirOption.setValueName(QStringLiteral("CMake AutoGen include directory"));
     parser.addOption(cmakeAutogenIncludeDirOption);
 
+    QCommandLineOption isMultiConfigOption(
+            QStringLiteral("cmake-multi-config"));
+    isMultiConfigOption.setDescription(
+            QStringLiteral("Set this option when using CMake with a multi-config generator"));
+    parser.addOption(isMultiConfigOption);
+
     QStringList arguments = QCoreApplication::arguments();
     parser.process(arguments);
 
@@ -354,13 +360,17 @@ int main(int argc, char **argv)
     }
 
     // 2) Process headers
+    const bool isMultiConfig = parser.isSet(isMultiConfigOption);
     for (auto mapIt = autoGenHeaders.begin(); mapIt != autoGenHeaders.end(); ++mapIt) {
         auto it = parseCacheEntries.find(mapIt.key());
         if (it == parseCacheEntries.end()) {
             continue;
         }
+        const QString pathPrefix = !isMultiConfig
+            ? QStringLiteral("../")
+            : QString();
         const QString jsonPath =
-                dir.filePath(QLatin1String("../") + mapIt.value() + QLatin1String(".json"));
+                dir.filePath(pathPrefix + mapIt.value() + QLatin1String(".json"));
         jsonFileList.push_back(jsonPath);
     }