Re: [libvirt] [PATCH] util: warn when passing a non-pointer to VIR_FREE

On 04/22/2011 12:21 PM, Christophe Fergeau wrote: That evaluates ptr twice. We can do better, by exploiting that the ternary operator can be used to determine the type of an expression without evaluating it. Gcc allows 1?(void*)expr:pointer (the resulting type is void*), but hates 1?(void*)expr:int (promoting to int provokes a warning): cc1: warnings being treated as errors remote.c: In function 'remoteDispatchListNetworks': remote.c:3684:70: error: pointer/integer type mismatch in conditional expression So how about: diff --git i/src/util/memory.h w/src/util/memory.h index 66b4c42..d77a295 100644 --- i/src/util/memory.h +++ w/src/util/memory.h @@ -1,7 +1,7 @@ /* * memory.c: safer memory allocation * - * Copyright (C) 2010 Red Hat, Inc. + * Copyright (C) 2010-2011 Red Hat, Inc. * Copyright (C) 2008 Daniel P. Berrange * * This library is free software; you can redistribute it and/or @@ -197,7 +197,11 @@ void virFree(void *ptrptr) ATTRIBUTE_NONNULL(1); * Free the memory stored in 'ptr' and update to point * to NULL. */ -# define VIR_FREE(ptr) virFree(&(ptr)) +/* The ternary ensures that ptr is a pointer and not an integer type, + * while evaluating ptr only once. For now, we intentionally cast + * away const, since a number of callers safely pass const char *. + */ +# define VIR_FREE(ptr) virFree((void *) (1 ? (const void *) &(ptr) : (ptr))) # if TEST_OOM -- Eric Blake eblake(a)redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org