(-lm check): If $GCC, append -fno-builtin to $CC for just this test.

1 files changed, 7 insertions, 1 deletions

diff --git a/configure.in b/configure.in
index 617fbe6a690..790ecec8f4e 100644
--- a/configure.in
+++ b/configure.in
@@ -1369,7 +1369,13 @@ AC_FUNC_ALLOCA
 
 # fmod, logb, and frexp are found in -lm on most systems.
 # On HPUX 9.01, -lm does not contain logb, so check for sqrt.
-AC_CHECK_LIB(m, sqrt(0.0) + t)
+old_CC="$CC"
+# GCC's implicit prototype for its built-in `sqrt' function conflicts
+# with autoconf's call, so disable the built-in function.
+test x$GCC = xyes && CC="$CC -fno-builtin"
+AC_CHECK_LIB(m, sqrt)
+CC="$old_CC"
+
 AC_CHECK_FUNCS(gettimeofday gethostname dup2 rename closedir mkdir rmdir \
 random lrand48 bcopy bcmp logb frexp fmod ftime res_init setsid \
 strerror fpathconf select mktime eaccess getpagesize tzset)