scons: Whitelist useful environment variables

Scons normally removes all environment variables that aren't
whitelisted from the build environment. This messes up things like
ccache, distcc, and the clang static analyzer. This changeset adds the
DISTCC_, CCACHE_, and CCC_ prefixes to the environment variable
whitelist.

diff --git a/SConstruct b/SConstruct
index a51acb15961d69ac847b8981fc94b0c07ecc88bd..22b63f02f9911f9ba42a647777bbf844c924b827 100755 (executable)
--- a/SConstruct
+++ b/SConstruct
@@ -183,9 +183,17 @@ use_vars = set([ 'AS', 'AR', 'CC', 'CXX', 'HOME', 'LD_LIBRARY_PATH',
                  'LIBRARY_PATH', 'PATH', 'PKG_CONFIG_PATH', 'PYTHONPATH',
                  'RANLIB', 'SWIG' ])
 
+use_prefixes = [
+    "M5",           # M5 configuration (e.g., path to kernels)
+    "DISTCC_",      # distcc (distributed compiler wrapper) configuration
+    "CCACHE_",      # ccache (caching compiler wrapper) configuration
+    "CCC_",         # clang static analyzer configuration
+    ]
+
 use_env = {}
 for key,val in os.environ.iteritems():
-    if key in use_vars or key.startswith("M5"):
+    if key in use_vars or \
+            any([key.startswith(prefix) for prefix in use_prefixes]):
         use_env[key] = val
 
 main = Environment(ENV=use_env)