Test if ccache is interfering with our life, and disable its habit of trying to compile already pre-processed versions of code if so.
In particular, clang has different semantic warnings based on if the warning arose from a macro or not. By trying to build preprocessed versions of code, we get more errors than we should. ccache allows us to disable this feature, opting instead to compile the original version instead of its preprocessed version. This makes ccache much slower for cache misses, but at least it becomes usable with QEMU/clang. Thanks to Peter Eisentraut for his writeup on the issue: http://peter.eisentraut.org/blog/2014/12/01/ccache-and-clang-part-3/ Signed-off-by: John Snow <js...@redhat.com> --- configure | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/configure b/configure index fbcbf50..75219a9 100755 --- a/configure +++ b/configure @@ -4172,6 +4172,33 @@ if compile_prog "" "" ; then getauxval=yes fi +######################################## +# check if ccache is interfering with +# semantic analysis of macros + +ccache=no +cat > $TMPC << EOF +static const int Z = 1; +#define fn() ({ Z; }) +#define TAUT(X) ((X) == Z) +#define PAREN(X, Y) (X == Y) +#define ID(X) (X) +int main(int argc, char *argv[]) +{ + int x = 0, y = 0; + x = ID(x); + x = fn(); + fn(); + if (PAREN(x, y)) return 0; + if (TAUT(Z)) return 0; + return 0; +} +EOF + +if ! compile_object; then + ccache=yes +fi + ########################################## # End of CC checks # After here, no more $cc or $ld runs @@ -5462,6 +5489,10 @@ if test "$numa" = "yes"; then echo "CONFIG_NUMA=y" >> $config_host_mak fi +if test "$ccache" = "yes"; then + echo "export CCACHE_CPP2=y" >> $config_host_mak +fi + # build tree in object directory in case the source is not in the current directory DIRS="tests tests/tcg tests/tcg/cris tests/tcg/lm32 tests/libqos tests/qapi-schema tests/tcg/xtensa tests/qemu-iotests" DIRS="$DIRS fsdev" -- 2.1.0
