[PATCH] D32435: clang-cl: Add support for /permissive-

[David Majnemer via cfe-commits]

On Mon, Apr 24, 2017 at 11:56 AM, Nico Weber <thakis at chromium.org> wrote:

> "Opting into the conforming mode, /permissive-, during the series of VS
> 2017 update is a commitment to keeping your code base clean and to fixing
> non-conforming constructs we fix conformance issues in Visual C++." [...]
> "By contrast /permissive- offers a useful conformance mode where input C++
> code is interpreted according to ISO C++ rules but also allows conforming
> extensions necessary to compile C++ on targets supported by Visual C++."
>
> I guess the second quote agrees with your interpretation.
>
> We already diag most of the things they already mention. The one thing we
> don't diag by default is Wmicrosoft-enum-forward-reference since that's
> only an Extension and not an ExtWarn. We don't expose -pedantic from
> clang-cl, so this seemed like a somewhat natural mapping to me.
>
> Should /permissive- map to -Wmicrosoft instead and turn on the parts of
> -Wmicrosoft that are Extensions?
>

Did you mean on or off? I think that their intent is that things like
__declspec remain OK. They want to diagnose non-conforming extensions like
crazy template stuff, bogus typedef syntax, bad main function definitions,
etc.


> Should we just ignore /permissive- and possibly make some of our
> -Wmicrosoft Extensions ExtWarns instead?
>
> On Mon, Apr 24, 2017 at 2:10 PM, David Majnemer <david.majnemer at gmail.com>
> wrote:
>
>> -pedantic means "Issue all the warnings demanded by strict ISO C and ISO
>> C++; reject all programs that use forbidden extensions, and some other
>> programs that do not follow ISO C and ISO C++."
>> I believe it is more akin to -fno-ms-compatibility as it disables
>> compatibility hacks.
>>
>> On Mon, Apr 24, 2017 at 11:02 AM, Nico Weber <thakis at chromium.org> wrote:
>>
>>> It does sound pretty similar to me from the blog post. I think this is a
>>> decent place to start from.
>>>
>>> On Apr 24, 2017 11:55 AM, "David Majnemer via Phabricator via
>>> cfe-commits" <cfe-commits at lists.llvm.org> wrote:
>>>
>>>> majnemer requested changes to this revision.
>>>> majnemer added a comment.
>>>> This revision now requires changes to proceed.
>>>>
>>>> I don't think this is correct. GDR (of Microsoft) says the behavior is
>>>> different: https://www.reddit.com/r/cpp/comm
>>>> <https://www.reddit.com/r/cpp/comments/5dh7j5/visual_c_introduces_permissive_for_conformance/da5fxjj/>
>>>>               LOG(INFO) << "n_window_index: " << n_window_index;
>>>> ents/5dh7j5/visual_c_introduces_permissive_for_conformance/da5fxjj/
>>>> <https://www.reddit.com/r/cpp/comments/5dh7j5/visual_c_introduces_permissive_for_conformance/da5fxjj/>
>>>>
>>>>
>>>> https://reviews.llvm.org/D32435
>>>>
>>>>
>>>>
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>>>
>>
>
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