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

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(a)redhat.com&gt; --- 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