[PATCH] PR17337 - Retain previous linkage of friend function declarations

[Richard Smith]

On Tue, Sep 24, 2013 at 9:14 AM, Alp Toker <alp at nuanti.com> wrote:

>  gcc and MSVC both intentionally* retain the language linkage, and they
> accept both test cases in the PR.
>
> I already explained in PR17337 why this special handling is important, and
> it becomes more so in the face of nested language linkage specifications:
>
>   http://llvm.org/bugs/show_bug.cgi?id=17337
>
> The previous release of clang correctly accepted the code, just like every
> other C++ compiler, up until checking was added in r171139 / r181163 so
> this is a recent rejects-valid regression.
>

If you can explain, with references to the standard, why you think we
should inherit the language linkage, then I'll agree. As far as I can see,
other compilers are getting this wrong. EDG rejects the code, just like we
do. g++ and MSVC are known to have weak implementations of the language
linkage rules.

clang r171139 states "The language linkage of redeclarations must match.
> GCC was already reporting an error for this."
>
> If you don't feel comfortable reviewing this patch could you give others a
> chance to take a look instead of marking the PR Invalid?
>
> * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41020
>
>
>
>
>
> On 24/09/2013 14:43, Richard Smith wrote:
>
> On Tue, Sep 24, 2013 at 3:00 AM, Alp Toker <alp at nuanti.com> wrote:
>
>> The previous language linkage needs to be retained as described in
>> [class.friend]p3 otherwise valid friend redeclarations differing only in
>> lexical linkage are rejected.
>>
>
>  [class.friend]p3 says the previous linkage (internal/external/no
> linkage) is retained, not the previous language linkage. Our current
> behavior appears to be correct here.
>
>
>> Fixes PR17337.
>>
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