From b13454eeb43137b0fed03b91688448d3a9c4ed8a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Wolfram=20R=C3=B6sler?= <wolfram@roesler-ac.de>
Date: Sun, 9 Jun 2019 22:10:58 +0200
Subject: [PATCH] Compile with Compiler Cache (ccache) if it's installed

Install with `sudo apt install ccache`.

Makes building a huge lot faster, especially when switching branches.
Nothing happens if ccache is not installed.

Example: (measured on my laptop)

```
$ ccache -C # clear the cache
$ rm -fr build
$ cd build
$ cmake -DWITH_XC_ALL=ON -DCMAKE_BUILD_TYPE=Release ..
$ time make -j4
...
real	5m8,817s
user	16m47,107s
sys	1m38,808s

$ rm -fr ../build/*
$ cmake -DWITH_XC_ALL=ON -DCMAKE_BUILD_TYPE=Release ..
$ time make -j4
...
real	0m32,571s
user	1m0,253s
sys	0m24,069s
```
---
 CMakeLists.txt | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ca8b0774..22646098 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -27,6 +27,13 @@ string(TOLOWER "${CMAKE_BUILD_TYPE}" CMAKE_BUILD_TYPE_LOWER)
 
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
 
+# Use the Compiler Cache (ccache) if it is installed
+# (install with: sudo apt get ccache)
+find_program (CCACHE_FOUND ccache)
+if (CCACHE_FOUND)
+    set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ccache)
+endif (CCACHE_FOUND)
+
 # Support Visual Studio Code
 include(CMakeToolsHelpers OPTIONAL)