The existing test whether "-lm" needs to be included or not is insufficient as it reports false negative on Fedora20/ppc64. This happens because sin(0.0) is a constant value which compiler can safely throw away and therefore there is no need to add "-lm". As the result, qemu-nbd/qemu-io/qemu-img tools cannot compile.
This adds a global variable and uses it in the test to prevent from optimization. Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> --- Changes: v2: * previous s/sin/log/ replacement removed, a global variable is used instead --- configure | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/configure b/configure index 23ecb37..6dd44a9 100755 --- a/configure +++ b/configure @@ -3453,7 +3453,7 @@ fi # Do we need libm cat > $TMPC << EOF #include <math.h> -int main(void) { return isnan(sin(0.0)); } +double x; int main(void) {return isnan(sin(x));} EOF if compile_prog "" "" ; then : -- 2.0.0