#298 Support buildng via compiler cache (ccache)

[f0rt]

Debian's Gitlab continous integration (CI) pipeline uses the compiler cache.

ccache depends on the CCACHE_DIR environment variable. As a consequence scons would need to propagate this environment variable. A possible patch could look like the following:

--- a/SConstruct
+++ b/SConstruct
@@ -201,6 +201,9 @@
 opts.Update(defenv)
 Help(opts.GenerateHelpText(defenv))

+for key in(filter(lambda key: key in os.environ, ['CCACHE_DIR'])):
+   defenv['ENV'][key] = os.environ[key]
+
 if defenv['TARGET_ARCH'] != 'x86':
    defenv['UNICODE'] = True

[Amir Szekely]

Let's do something simpler like:

if 'CCACHE_DIR' in os.environ:
  defenv['ENV']['CCACHE_DIR'] = os.environ['CCACHE_DIR']

[f0rt]

I agree. I would appreciate if you could integrate your code.

[Amir Szekely]

Have you tried something like scons CC="CCACHE_DIR=/tmp/whatever ccache"? Seems to work for me in a very limited test.

[f0rt]

Your proposal to propagate the CCACHE_DIR environment variable via the command line argument CC="CACHE_DIR=/tmp/whatever ccache" seems to work.

I assume the same has to be done for CXX and for the cross compilers (i686-w64-mingw32-gcc, i686-w64-mingw32-g++).

This feels more like a workaround than a solution.

main.c

int main(int argc, char *argv[]) { return 42; }

SConstruct

defenv = DefaultEnvironment()
Export('defenv')

opts = Variables()
opts.Add(('CC', 'Override C compiler', None))
opts.Update(defenv)

defenv.Program('main.c')
print(defenv.Dump())

Test setting of ${CCACHE_DIR} environment variable

scons CC='CCACHE_DIR=/tmp/ccache; echo $${CCACHE_DIR}'

scons: Building targets ...
CCACHE_DIR=/tmp/ccache; echo ${CCACHE_DIR} -o main.o -c main.c
/tmp/ccache -o main.o -c main.c
CCACHE_DIR=/tmp/ccache; echo ${CCACHE_DIR} -o main main.o
/tmp/ccache -o main main.o
scons: done building targets.

[Amir Szekely]

SCons doesn't have built-in support for ccache, so it's all workarounds unless there is a proper tool definition. Don't you already need to override CC and CXX with ccache anyway?

If we add a tool like the ones in SCons/Tools, then it would be an even simpler scons TOOLS=ccache.

[f0rt]

Thanks a lot for your explanation. I am going to give the idea of overriding CC adn CXX more thought.

Currently there is no need to override CC and CXX.

scons picks up the installed GNU C and C++ compiler (symbolic link named as the respective compiler pointing to the ccache executable).

For example the following command line is used to build the makensis compiler

scons APPEND_CCFLAGS="-Wdate-time -D_FORTIFY_SOURCE=2 -g -O2 -fdebug-prefix-map=/builds/debian/nsis/debian/output/nsis-3.06.1=. -fstack-protector-strong -Wformat -Werror=format-security" APPEND_LINKFLAGS="-Wl,-z,relro -Wl,-z,now"  VERSION=3.06.1-1+salsaci VER_MAJOR=3 VER_MINOR=06 VER_REVISION=1 PREFIX=/usr PREFIX_CONF=/etc CHMDOCS=0 STRIP_CP=no  UNICODE=yes SKIPPLUGINS=all SKIPSTUBS=all SKIPUTILS='Library/RegTool,MakeLangId,Makensisw,NSIS Menu,UIs,SubStart,zip2exe' SKIPDOC=COPYING makensis

and scons is invoked for cross compiling of stubs, plugins and utilities such as:

scons  VERSION=3.06.1-1+salsaci VER_MAJOR=3 VER_MINOR=06 VER_REVISION=1 PREFIX=/usr PREFIX_CONF=/etc CHMDOCS=0 STRIP_CP=no  UNICODE=yes SKIPUTILS=',MakeLangId,Makensisw,NSIS Menu,SubStart,VPatch/Source/GenPat,zip2exe' SKIPDOC=COPYING PREFIX_PLUGINAPI_INC=/usr/i686-w64-mingw32/include/ PREFIX_PLUGINAPI_LIB=/usr/i686-w64-mingw32/lib/ XGCC_W32_PREFIX=i686-w64-mingw32- TARGET_ARCH=x86 stubs plugins util