Re: [PATCH v3] git-compat-util.h: implement a different ARRAY_SIZE macro for for safely deriving the size of array
- From
Jeff King <peff@peff.net>
- Date
- Apr 30, 2015, 18:19 UTC
- Message-ID
- <20150430181901.GA23431@peff.net>
- In-Reply-To
- <xmqq4mnx1or9.fsf@gitster.dls.corp.google.com>
On Thu, Apr 30, 2015 at 10:59:06AM -0700, Junio C Hamano wrote:
Show 28 quoted lines
> Junio C Hamano <gitster@pobox.com> writes: > > > Jeff King <peff@peff.net> writes: > > > >> ISTR that you compile with "-std=c89". typeof was added in c99, I think > >> (and was a GNU extension before that). I wonder if that is fooling the > >> gcc version-check. > > > > Yeah, I think that is very likely. > > Yes. One workaround is to explicitly say that we accept the GNU > extension in the source, perhaps. > > git-compat-util.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/git-compat-util.h b/git-compat-util.h > index f1f8f23..7fad5aa 100644 > --- a/git-compat-util.h > +++ b/git-compat-util.h > @@ -62,8 +62,8 @@ > # if GIT_GNUC_PREREQ(3, 1) > /* &arr[0] degrades to a pointer: a different type from an array */ > # define BARF_UNLESS_AN_ARRAY(arr) \ > - BUILD_ASSERT_OR_ZERO(!__builtin_types_compatible_p(typeof(arr), \ > - typeof(&(arr)[0]))) > + BUILD_ASSERT_OR_ZERO(!__builtin_types_compatible_p(__typeof__(arr), \ > + __typeof__(&(arr)[0])))
That seems like a reasonable fix, provided that other gcc-compatible compilers implement the GNU-compatible name. I just tried with clang 3.5, and it seems to work fine.
And I was wrong about "typeof". It is not in C99 at all. So I think it is really a matter of whether you are in the default "-std=gnu89" mode or not, as to whether the compiler imports the "typeof" keyword, or if it must be hidden in the compiler-reserved area (starting with "__").
-Peff