From 41f7cd2411c6500bd6a07be63f3adb1c0eb890a7 Mon Sep 17 00:00:00 2001
From: Manuel Nickschas <sputnick@quassel-irc.org>
Date: Sat, 16 Jun 2018 21:58:51 +0200
Subject: [PATCH] cmake: Enable ccache by default, if available

Check for the existence of the ccache binary, and enable ccache
support if available. This avoids the need for hacks using PATH
or the CXX variable to make ccache work.

The automatic detection can be disabled by passing -DUSE_CCACHE=OFF
to CMake (may be useful for distributors having their own ccache
infrastructure in place).

Reorder things in the top-level CMakeLists.txt a bit, because ccache
should be enabled before calling project() (which checks compiler
settings).
---
 CMakeLists.txt                     | 40 ++++++++++++++++++++++++------
 INSTALL                            |  6 +++++
 cmake/QuasselCompileSettings.cmake |  9 -------
 3 files changed, 38 insertions(+), 17 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5668fcf0..a59ab825 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,26 +6,49 @@
 # General setup
 #####################################################################
 
-project(QuasselIRC)
-
 # Versions
 set(QUASSEL_MAJOR  0)
 set(QUASSEL_MINOR 13)
 set(QUASSEL_PATCH  0)
 set(QUASSEL_VERSION_STRING "0.13-pre")
 
-# Output CMake version and build type for debug reasons
+# Build type
+if (CMAKE_CONFIGURATION_TYPES)
+    set(CMAKE_CONFIGURATION_TYPES Release RelWithDebInfo Debug Debugfull Profile)
+    set(CMAKE_CONFIGURATION_TYPES "${CMAKE_CONFIGURATION_TYPES}" CACHE STRING "These are the configuration types we support" FORCE)
+endif()
+
+if(NOT CMAKE_BUILD_TYPE)
+    set(CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "Choose the type of build, options are: Release RelWithDebInfo Debug Debugfull Profile None" FORCE)
+endif()
+
+# Output CMake and Quassel versions as well as build type for debug reasons
+message(STATUS "Building Quassel ${QUASSEL_VERSION_STRING}...")
 message(STATUS "Using CMake ${CMAKE_VERSION}")
 message(STATUS "CMake build type: ${CMAKE_BUILD_TYPE}")
 
-# Tell CMake about or own modules
-set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake)
+# Support ccache if found
+# This should happen before calling project(), so compiler settings are validated.
+option(USE_CCACHE "Enable support for ccache if available" ON)
+if (USE_CCACHE)
+    message(STATUS "Checking for ccache")
+    find_program(CCACHE_PROGRAM ccache)
+    if (CCACHE_PROGRAM)
+        set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE_PROGRAM}")
+        message(STATUS "Checking for ccache - enabled")
+    else()
+        message(STATUS "Checking for ccache - not found")
+    endif()
+endif()
+
+# Set up project
+project(Quassel C CXX)
 
 # General conveniences
 set(CMAKE_AUTOMOC ON)
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 
-# Include various CMake modules...
+# Include various CMake modules
 include(CMakePushCheckState)
 include(CheckFunctionExists)
 include(CheckIncludeFile)
@@ -33,7 +56,8 @@ include(CheckCXXSourceCompiles)
 include(CMakeDependentOption)
 include(FeatureSummary)
 
-# ... and our own stuff
+# Tell CMake about or own modules
+set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake)
 include(QuasselCompileSettings)
 include(QuasselMacros)
 
@@ -41,7 +65,7 @@ include(QuasselMacros)
 # Options and variables that can be set on the command line
 #####################################################################
 
-# First, choose a Qt version. We support USE_QT5 and USE_QT4; if neither is set, Qt5 will be used
+# Choose a Qt version. We support USE_QT5 and USE_QT4; if neither is set, Qt5 will be used
 option(USE_QT5 "Enable support for Qt5" OFF)
 if (USE_QT5) # takes precedence
     set(USE_QT4 OFF)
diff --git a/INSTALL b/INSTALL
index 1ad90c36..a7a1bd99 100644
--- a/INSTALL
+++ b/INSTALL
@@ -74,6 +74,12 @@ options here:
 -DWANT_(CORE|QTCLIENT|MONO)=(ON|OFF)
     Choose which Quassel binaries to build.
 
+-DUSE_CCACHE=ON
+    Enable ccache if the ccache binary is available. This avoids the need for
+    hacks using PATH or the CXX variable to make ccache work.
+    Distributors may want to disable automatic detection if they have their
+    own caching mechanism set up.
+
 -DUSE_QT4=ON
     Build against the deprecated Qt4 instead of the default Qt5. Note that you
     should empty your build directory when switching between Qt versions,
diff --git a/cmake/QuasselCompileSettings.cmake b/cmake/QuasselCompileSettings.cmake
index b499a18f..67cfd643 100644
--- a/cmake/QuasselCompileSettings.cmake
+++ b/cmake/QuasselCompileSettings.cmake
@@ -7,15 +7,6 @@
 
 include(CheckCXXCompilerFlag)
 
-if (CMAKE_CONFIGURATION_TYPES)
-    set(CMAKE_CONFIGURATION_TYPES Release RelWithDebInfo Debug Debugfull Profile)
-    set(CMAKE_CONFIGURATION_TYPES "${CMAKE_CONFIGURATION_TYPES}" CACHE STRING "These are the configuration types we support" FORCE)
-endif()
-
-if(NOT CMAKE_BUILD_TYPE)
-    set(CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "Choose the type of build, options are: None Debug Release RelWithDebInfo Debug Debugfull Profile" FORCE)
-endif()
-
 # Qt debug flags
 set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS_DEBUG QT_DEBUG)
 set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS_DEBUGFULL QT_DEBUG)
-- 
2.20.1