[cfe-dev] Enabling strong enum extensions under C

[Saleem Abdulrasool via cfe-dev]

On Fri, Feb 19, 2016 at 1:17 PM, Martin J. O'Riordan via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> I have the same kind of dilemma - I really like having a "strictly
> conforming" option because I love Standards, but realistically I need them
> to be supplemented by a relaxed mode that permits extensions.
>
> What I think would be the right thing for Clang, would be for '-std=XXX'
> to enforce the ISO definition of XXX, but to be able to supplement it with
> an additional option or options that enabled the extensions or relaxed the
> ISO rules (warnings of divergence are still good).  Normally when I use
> '-std=XXX', I also find I have to use at least ' -U__STRICT_ANSI__' because
> the extended or non-Standard behaviour is what I often want; and sometimes
> other additional options.  But having '-std=XXX' mean exactly the ISO
> definition is really useful, and cool.
>
> Ironically, having '-std=XXX' be really strict about ISO compliance is
> almost certainly the wrong thing for my code; for example it means enabling
> exceptions which are simply too expensive for embedded; but I would still
> like to tell the compiler to enforce strict ISO conformance rules - unless
> I have supplemented it with options to relax particular constraints.
> Sometimes we use '-std=XXX' to select a dialect (e.g. C++11 versus C++14),
> but then have to supplement it by a bunch of other options that tune it to
> our actual non-Standard needs.  But I still need warnings and error
> messages, they tell me where I need to be very specific about what and why
> I am doing something that strays outside the ISO interpretation.
>
> An alternative would to be to add something like '-fstrict-iso' to make
> '-std=XXX' be strict, but my own feeling is that strict should be the
> default, and relaxed should be the deliberately selected alternative.
>

It seems that there is some interest in keeping the default be standards
conforming.  It would be nice to get a consensus on this issue so that we
can move forward.


>         MartinO
>
> -----Original Message-----
> From: cfe-dev [mailto:cfe-dev-bounces at lists.llvm.org] On Behalf Of Joerg
> Sonnenberger via cfe-dev
> Sent: 19 February 2016 15:20
> To: cfe-dev at lists.llvm.org
> Subject: Re: [cfe-dev] Enabling strong enum extensions under C
>
> On Tue, Feb 16, 2016 at 09:46:27AM -0500, Nico Weber via cfe-dev wrote:
> > Personally, I'd like if -std=c11 would give you C11 without extensions.
>
> Speaking with OS developer hat, it is not practical to disable all
> extensions like the protected versions of keywords or attributes.
>
> Joerg
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-- 
Saleem Abdulrasool
compnerd (at) compnerd (dot) org
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