[Qemu-devel] [RFC v2 1/9] configure: test if _Generic works as expected

[Eduardo Habkost]

Test if _Generic works as expected, and set HAVE_C11_GENERIC
config variable if it does.

Signed-off-by: Eduardo Habkost <address@hidden>
---
 configure | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/configure b/configure
index d1ce33bc79..b29bce0b53 100755
--- a/configure
+++ b/configure
@@ -1548,6 +1548,22 @@ EOF
   fi
 fi
 
+# Ensure we support _Generic, and that it takes type qualifiers into account
+have_c11_generic=
+cat > $TMPC << EOF
+const int *p;
+typedef typeof(_Generic(p,
+                        const int *: (int *)0,
+                        int *: 0,
+                        default: 0)) T;
+T foo;
+int x(void);
+int x(void) { return *foo; }
+EOF
+if do_cc $QEMU_CFLAGS -Werror -c -o $TMPO $TMPC;then
+  have_c11_generic=yes
+fi
+
 # Workaround for http://gcc.gnu.org/PR55489.  Happens with -fPIE/-fPIC and
 # large functions that use global variables.  The bug is in all releases of
 # GCC, but it became particularly acute in 4.6.x and 4.7.x.  It is fixed in
@@ -5751,6 +5767,10 @@ if test "$have_sysmacros" = "yes" ; then
   echo "CONFIG_SYSMACROS=y" >> $config_host_mak
 fi
 
+if test "$have_c11_generic" = "yes" ; then
+  echo "HAVE_C11_GENERIC=y" >> $config_host_mak
+fi
+
 # Hold two types of flag:
 #   CONFIG_THREAD_SETNAME_BYTHREAD  - we've got a way of setting the name on
 #                                     a thread we have a handle to
-- 
2.11.0.259.g40922b1