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

[Nico Weber via cfe-commits]

On Mon, Apr 24, 2017 at 10:00 PM, David Majnemer <david.majnemer at gmail.com>
wrote:

>
>
> 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?
>

On.


> I think that their intent is that things like __declspec remain OK.
>

Nothing in -Wmicrosoft warns on __declspec.


> They want to diagnose non-conforming extensions like crazy template stuff,
> bogus typedef syntax, bad main function definitions, etc.
>

Right. The only thing it currently makes cl warn on that clang-cl doesn't
warn on by default is Wmicrosoft-enum-forward-reference, which is an
Extension warning, not an ExtWarn. So mapping /permissive- to -Wmicrosoft
would make clang-cl diagnose forward-declared enums like it does with 2017
cl.


>
>
>> 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
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> cfe-commits mailing list
>>>>> cfe-commits at lists.llvm.org
>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>>>>>
>>>>
>>>
>>
>
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