On Oct 21, 2014, at 12:07 PM, Andrew Morton <[email protected]> wrote:
> On Sat, 18 Oct 2014 17:39:10 -0700 [email protected] (Eric W. Biederman) > wrote: > >> Jeff Kirsher <[email protected]> writes: >> >>> From: Mark Rustad <[email protected]> >>> >>> Resolve missing-field-initializers warnings in W=2 builds by >>> using designated initialization. >> >> ick. No. >> >> That gcc warning makes no sense. In this case heeding it makes the code >> significantly uglier and significantly more confusing. >> > > Yeah, it's not pretty. > >>> --- a/kernel/sysctl.c >>> +++ b/kernel/sysctl.c >>> @@ -257,7 +257,7 @@ static struct ctl_table sysctl_base_table[] = { >>> .mode = 0555, >>> .child = dev_table, >>> }, >>> - { } >>> + { .procname = NULL } >>> }; > > We use { } to mean "all zero" in 12 squillion places. Do they all warn > or is there something special about this site? Well, about 6 squillion of them are { }, a GCC extension, and the other 6 squillion are { 0 }. Both forms generate the warning. There is nothing special about this site. I just was resolving warnings in order to find some that had some significance. A flood of 125,000 warnings is too awful to look at. I got it down to around 1,500 and did find a few hazards and sent patches to address them, which have been accepted in one form or another. I had sent patches to add diagnostic control macros to allow a warning to be turned off for a range of code. I would have liked to use them to provide something like a ZERO_ENTRY macro that would have looked something like this: #define ZERO_ENTRY DIAG_PUSH DIAG_IGNORE(missing-field-initializers) { 0 } DIAG_POP which would have provided a standard way to get a zero entry that would have avoided the warnings. Borislav was quite opposed to the notion of diagnostic control macros. I rather like the notion as long as their use is tightly controlled. I'm sure that we both feel that there should be a form that the compiler does not generate this warning for as a preferred solution. The designated initialization is at best a 3rd-best solution, though naming the field used to identify the end of the table is not a bad thing either. I do like enabling lots of additional warnings to find problems in code, but when it results in such a flood of messages it is not a very useful approach, hence my tendency to want to address them somehow, so that meaningful ones can be noticed. -- Mark Rustad, Networking Division, Intel Corporation
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