https://bugs.gentoo.org/879653
--- a/configure.in
+++ b/configure.in
@@ -194,7 +194,7 @@ test -n "$LDFLAGS" && MYLDFLAGS="$LDFLAGS $MYLDFLAGS"
 AC_C_BIGENDIAN(MYCPPFLAGS="$MYCPPFLAGS -D_MYBIGEND")
 
 printf 'checking for useless warnings... '
-if printf 'main() {}' | $CC -xc \
+if printf 'int main(void) {}' | $CC -xc \
   -Wno-unused-but-set-variable -Wno-unused-but-set-parameter -o config.tmp - >config.tmp 2>&1
 then
   MYCFLAGS="$MYCFLAGS -Wno-unused-but-set-variable -Wno-unused-but-set-parameter"