On Wed, Nov 01, 2017 at 05:59:54PM -0600, Martin Sebor wrote: > On 10/30/2017 06:20 AM, Antons Suspans wrote: > > Why is -Wold-style-definition off by default and not implied by -Wall, > > -Wextra? The following code might be a marginal example, which is > > compiled without warning about missing prototype and unchecked args > > (gcc-5.3.0 -Wall -Wextra ex.c). > > I recently wondered the same thing. Functions without a prototype > have been deprecated since C99. As the C committee is starting to > work on C2X it will consider removing (a subset of) deprecated features. > I think it would make sense to include the option in -Wall now, well > ahead of C2X being finalized (it arguably should been done years ago). > If you'd like to see such a change I suggest opening a request in Bugzilla. Thank you for your reply and information! I was pondering this and, frankly, I am not sure I fully understand the situation, and how gcc warnings are balanced between the standard, the existent C code, and good practices (for instance, I'd expect C11 6.7.6.3p3 to be fatal). I have posted a request to include -Wstrict-prototypes in -Wextra: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82922 The following options (and their antecedents) seemed related: 1. -Wimplicit-function-declaration (-Wimplicit | -Wall | -std=c99 | -std=gnu99 or later) 2. -Wimplicit-int (-Wimplicit | -Wall | -std=c99 | -std=gnu99 or later) 3. -Wmissing-parameter-type (-Wextra) 4. -Wold-style-declaration (-Wextra) 5. -Wold-style-definition 6. -Wstrict-prototypes 7. -Wmissing-declarations 8. -Wmissing-prototypes #1 and #2 are both imposed since C99, and #3 is taken over by #2 since C99. #7 and #8 are good for header discipline but don't seem crucial. My concern was calling unprototyped functions and I think it is completely covered by #1 + #6 (#5 cases hit #6 too). Perhaps #6 (i.e. -Wstrict-prototypes) is not deserving a place along #1 in -Wall until the standard changes accordingly, but maybe it is indeed viable in -Wextra (#4 is there). Antons P.S. Martin, please excuse me for the duplicate message.
