Re: [PATCH] coverity: provide Coverity-friendly MIN_CONST and MAX_CONST

[Eric Blake]

On 6/29/20 10:16 AM, Paolo Bonzini wrote:
> Coverity's parser chokes on __builtin_choose_expr inside a constant
> expression.  Since it is used only to raise compilation errors for
> non-constant arguments, we can just assume there are no such errors
> in the Coverity runs, and define MIN_CONST and MAX_CONST to the
> "classic" ternary-operator-based definitions of minimum and maximum.
>
> Reported-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   include/qemu/osdep.h | 17 ++++++++++++-----
>   1 file changed, 12 insertions(+), 5 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

I wrote a variant in the meantime, and in comparing the two, the only 
major difference was that I added a line:

    Fixes: CID 1429992, CID 1429995, CID 1429997, CID 1429999

in the commit message, as well as a comment in osdep.h:

diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 0d26a1b9bd07..98bc7156fa9b 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -250,7 +250,8 @@ extern int daemon(int, int);
  * Note that neither form is usable as an #if condition; if you truly
  * need to write conditional code that depends on a minimum or maximum
  * determined by the pre-processor instead of the compiler, you'll
- * have to open-code it.
+ * have to open-code it.  Sadly, Coverity is severely confused by the
+ * constant variants, so we have to dumb things down there.
  */
 #undef MIN
 #define MIN(a, b)                                       \


I'm fine whether or not we include that.

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org