Cannot build with ccache & clang - cmake issue?

[Milian Wolff]

Hey all,

is anyone else using ccache in combination with clang to build KF5? A few days 
ago it worked for me, so maybe something in cmake git broke (we do use cmake 
git for KF5, right?). In order to use ccache with clang, I export the 
following:

export CXX=ccache /usr/bin/clang++ -Qunused-arguments
export CC=ccache /usr/bin/clang -Qunused-arguments

This worked for quite some time for me and I build KDE4 apps happily with it. 
Trying to build KF5 today yielded:

# kdesrc-build running: 'make'
# from directory: /home/milian/projects/kf5/build/extragear/utils/kdesrc-build
-- The C compiler identification is unknown
-- The CXX compiler identification is unknown
-- Check for working C compiler: /usr/bin/ccache
-- Check for working C compiler: /usr/bin/ccache -- broken
CMake Error at 
/home/milian/projects/compiled/kf5/share/cmake-3.0/Modules/CMakeTestCCompiler.cmake:61 
(message):
  The C compiler "/usr/bin/ccache" is not able to compile a simple test 
program
  It fails with the following output:
<snip>
  Building C object
  CMakeFiles/cmTryCompileExec3325854589.dir/testCCompiler.c.o

  /usr/bin/ccache -o
  CMakeFiles/cmTryCompileExec3325854589.dir/testCCompiler.c.o -c
  /home/milian/projects/kf5/build/extragear/utils/kdesrc-
build/CMakeFiles/CMakeTmp/testCCompiler.c


  /usr/bin/ccache: invalid option -- 'o'
<snip>

Of course this will fail. Why is it ignoring the other values set int CC/CXX? 
Can someone tell me how to configure CMake git to use clang & ccache in 
another way?

Thanks
-- 
Milian Wolff
mail at milianw.de
http://milianw.de