configure: Make epoll_create1 test work around SPARC glibc bug
Work around a SPARC glibc bug which caused the epoll_create1 configure
test to wrongly claim that the function was present. Some versions of
SPARC glibc provided the function in the library but didn't declare
it in the include file; the result is that gcc warns about an implicit
declaration but a link succeeds. So we reference the function as a
value rather than a function call to induce a compile time error
if the declaration was not present.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/configure b/configure
index de44bac..2bbbbf5 100755
--- a/configure
+++ b/configure
@@ -2225,7 +2225,15 @@
int main(void)
{
- epoll_create1(0);
+ /* Note that we use epoll_create1 as a value, not as
+ * a function being called. This is necessary so that on
+ * old SPARC glibc versions where the function was present in
+ * the library but not declared in the header file we will
+ * fail the configure check. (Otherwise we will get a compiler
+ * warning but not an error, and will proceed to fail the
+ * qemu compile where we compile with -Werror.)
+ */
+ epoll_create1;
return 0;
}
EOF
