[libvirt] [PATCH v2 15/42] m4: disable gcc8 -Wcast-function-type warnings from -Wextra

[Daniel P. Berrangé]

The -Wextra flag bundle gained a new warning -Wcast-function-type.
This complains if you cast between two function prototypes where
the number of parameters or their data types are not compatible.
Unfortunately we need such "bad" function casts for our event
callbacks. It is possible to silence the warning by first casting
to the generic "void (*)(void)" function prototype, but that is
rather ugly to add throughout libvirt code.

Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
---
 m4/virt-compile-warnings.m4 | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/m4/virt-compile-warnings.m4 b/m4/virt-compile-warnings.m4
index 918764d362..fc185aef38 100644
--- a/m4/virt-compile-warnings.m4
+++ b/m4/virt-compile-warnings.m4
@@ -175,6 +175,8 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[
     # with gl_MANYWARN_COMPLEMENT
     # So we have -W enabled, and then have to explicitly turn off...
     wantwarn="$wantwarn -Wno-sign-compare"
+    # We do "bad" function casts all the time for event callbacks
+    wantwarn="$wantwarn -Wno-cast-function-type"
 
     # GNULIB expects this to be part of -Wc++-compat, but we turn
     # that one off, so we need to manually enable this again
-- 
2.14.3