On 1/4/19 10:00 AM, Eric Blake wrote:
We might as well take advantage of gcc's extensions for a safer MIN()/MAX() macro.
Signed-off-by: Eric Blake <eblake@redhat.com> ---
RFC because we could also try to fall back to older gcc's typeof(a)_a=(a) when the newer __auto_type _a=(a) is not present, and because I don't know how to properly probe for __auto_type and/or typeof support in clang (I know that clang added __auto_type in 2015, per https://reviews.llvm.org/D12686); I also don't know if we have officially stated that we require gcc/clang (because of attribute((cleanup)), which really cannot be emulated without extensions), or if we still try to allow compilation with other compilers; if we have, I don't know if we have declared a minimum compiler version that we demand (qemu has recently demanded gcc 4.8 or clang 3.4 [branded 5.1 on Apple]).
Also RFC because: In file included from util/virlog.c:46: util/virutil.h:43:22: error: braced-group within expression allowed only inside a function # define MAX(a, b) ({ \ ^ util/virlog.c:899:29: note: in expansion of macro 'MAX' # define JOURNAL_BUF_SIZE (MAX(INT_BUFSIZE_BOUND(int), sizeof(uint64_t))) ^~~ util/virlog.c:904:18: note: in expansion of macro 'JOURNAL_BUF_SIZE' char (*bufs)[JOURNAL_BUF_SIZE], (*bufs_end)[JOURNAL_BUF_SIZE]; ^~~~~~~~~~~~~~~~ util/virutil.h:43:22: error: braced-group within expression allowed only inside a function # define MAX(a, b) ({ \ ^ util/virlog.c:899:29: note: in expansion of macro 'MAX' # define JOURNAL_BUF_SIZE (MAX(INT_BUFSIZE_BOUND(int), sizeof(uint64_t))) ^~~ util/virlog.c:904:49: note: in expansion of macro 'JOURNAL_BUF_SIZE' char (*bufs)[JOURNAL_BUF_SIZE], (*bufs_end)[JOURNAL_BUF_SIZE]; ^~~~~~~~~~~~~~~~ -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org