Fail if __FAST_MATH__ is defined.

diff --git a/config.h.in b/config.h.in
index af1b010aa9111c8475a75dc6def5572d3f480215..bf696d3df5d35274fd38698d2a17f8c7423a5a92 100644 (file)
--- a/config.h.in
+++ b/config.h.in
@@ -2,6 +2,12 @@
 # error "glibc cannot be compiled without optimization"
 #endif
 
+/* Another evil option when it comes to compiling the C library is
+ *    --ffast-math since it alters the ABI.  */
+#ifdef __FAST_MATH__
+# error "glibc must not be compiled with --fast-math"
+#endif
+
 /* Define if using GNU ld, with support for weak symbols in a.out,
    and for symbol set and warning messages extensions in a.out and ELF.
    This implies HAVE_WEAK_SYMBOLS; set by --with-gnu-ld.  */