[Build] Add precompiled headers for Qt-backed executables (#7235)

* [Build] Add precompiled headers for Qt-backed executables

Reparsing QtCore/QtGui/QtWidgets/QtNetwork in ~460 client translation
units is the dominant compilation cost. Precompile the two common layers:
- qtcore_pch.h (Qt Core only; safe even for headless Servatrice)
- qtwidgets_pch.h (adds Gui/Widgets/Network; used by Cockatrice and Oracle)

target_precompile_headers() requires CMake 3.16, now the project minimum.
Estimated 30-50% faster client rebuilds.

* [Build] Format qtwidgets precompiled header

clang-format include regrouping and a missing trailing newline.

* [Build] Add PCH-aware ccache sloppiness config; format cmake/pch headers

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

.ci/compile.sh

@@ -149,6 +149,9 @@ if [[ $MAKE_TEST ]]; then
 fi
 if [[ $USE_CCACHE ]]; then
   flags+=("-DUSE_CCACHE=1")
+  # PCH-aware caching is required or ccache refuses to cache any TU that
+  # consumes a precompiled header, silently recompiling everything on every run.
+  ccache --set-config sloppiness=pch_defines,time_macros
   if [[ $CCACHE_SIZE ]]; then
     # note, this setting persists after running the script
     ccache --max-size "$CCACHE_SIZE"

CMakeLists.txt

@@ -44,6 +44,10 @@ if(USE_CCACHE)
   if(CCACHE_PROGRAM)
     # Support Unix Makefiles and Ninja
     set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE_PROGRAM}")
+    # PCH-aware caching, matching .ci/compile.sh: without this ccache refuses
+    # to cache any TU that consumes a precompiled header, so every PCH-backed
+    # target recompiles from scratch on each build.
+    execute_process(COMMAND ${CCACHE_PROGRAM} --set-config sloppiness=pch_defines,time_macros)
     message(STATUS "Found CCache ${CCACHE_PROGRAM}")
   endif()
 endif()

cmake/pch/qtcore_pch.h

@@ -0,0 +1,24 @@
+/** @file qtcore_pch.h
+ *  @brief Precompiled header for all Qt targets (Qt Core only).
+ *
+ * Safe for every target that links Qt Core, including the headless
+ * Servatrice binary. Keep this header free of any widget/gui types.
+ */
+
+#include <QBasicTimer>
+#include <QByteArray>
+#include <QDateTime>
+#include <QDebug>
+#include <QFile>
+#include <QHash>
+#include <QList>
+#include <QLoggingCategory>
+#include <QMap>
+#include <QMetaObject>
+#include <QObject>
+#include <QRandomGenerator>
+#include <QSharedPointer>
+#include <QString>
+#include <QStringList>
+#include <QTimer>
+#include <QVariant>

cmake/pch/qtwidgets_pch.h

@@ -0,0 +1,30 @@
+/** @file qtwidgets_pch.h
+ *  @brief Precompiled header for GUI targets (Cockatrice client, Oracle).
+ *
+ * Includes the Qt Core precompiled header plus the heavy Gui, Widgets and
+ * Network layers that virtually every client translation unit re-parses.
+ * Do not use on Servatrice (headless, QT_DONT_USE_QTGUI).
+ */
+
+#include "qtcore_pch.h"
+
+#include <QAction>
+#include <QApplication>
+#include <QFrame>
+#include <QGraphicsItem>
+#include <QGraphicsScene>
+#include <QGraphicsView>
+#include <QImage>
+#include <QLabel>
+#include <QLayout>
+#include <QMainWindow>
+#include <QMenu>
+#include <QNetworkAccessManager>
+#include <QNetworkReply>
+#include <QPainter>
+#include <QPushButton>
+#include <QScrollArea>
+#include <QTabWidget>
+#include <QToolBar>
+#include <QTreeWidget>
+#include <QWidget>

cockatrice/CMakeLists.txt

@@ -516,6 +516,8 @@ qt6_add_executable(
   MANUAL_FINALIZATION
 )
 
+target_precompile_headers(cockatrice PRIVATE "${CMAKE_SOURCE_DIR}/cmake/pch/qtwidgets_pch.h")
+
 qt6_add_shaders(
   cockatrice
   "onboarding_shaders"

format.sh

@@ -18,6 +18,7 @@ include=("cockatrice/src" \
 libcockatrice_* \
 "oracle/src" \
 "servatrice/src" \
+"cmake/pch" \
 "tests")
 exclude=("libcockatrice_rng/libcockatrice/rng/sfmt/" \
 "libcockatrice_utility/libcockatrice/utility/peglib.h" \

oracle/CMakeLists.txt

@@ -112,6 +112,8 @@ qt6_add_executable(
   MANUAL_FINALIZATION
 )
 
+target_precompile_headers(oracle PRIVATE "${CMAKE_SOURCE_DIR}/cmake/pch/qtwidgets_pch.h")
+
 # ------------------------
 # Link libraries
 # ------------------------

servatrice/CMakeLists.txt

@@ -95,6 +95,8 @@ set(DESKTOPDIR
 # Build servatrice binary and link it
 add_executable(servatrice MACOSX_BUNDLE ${servatrice_MOC_SRCS} ${servatrice_RESOURCES_RCC} ${servatrice_SOURCES})
 
+target_precompile_headers(servatrice PRIVATE "${CMAKE_SOURCE_DIR}/cmake/pch/qtcore_pch.h")
+
 if(CMAKE_HOST_SYSTEM MATCHES "FreeBSD")
   target_link_libraries(
     servatrice libcockatrice_deck_list libcockatrice_network_server_remote Threads::Threads ${SERVATRICE_QT_MODULES}