[PATCH] Remove dead code (check for impossible condition) in Sema::ActOnFriendFunctionDecl

[Stephen Lin]

Thank you, I've already verified that no tests are affected, so this
is good to be picked up.

On Wed, Mar 20, 2013 at 1:06 AM, John McCall <rjmccall at apple.com> wrote:
> On Mar 18, 2013, at 10:56 AM, Stephen Lin <swlin at post.harvard.edu> wrote:
>> I found code in Sema::ActOnFriendFunctionDecl() which I am almost sure
>> is dead and would like to remove it.
>>
>> The code in question is the following check:
>>
>>    if (!Previous.empty() && DC->Equals(CurContext))
>>      Diag(DS.getFriendSpecLoc(),
>>           getLangOpts().CPlusPlus11 ?
>>             diag::warn_cxx98_compat_friend_is_member :
>>             diag::err_friend_is_member);
>>
>> which happens immediately after this loop:
>>
>>    DC = CurContext;
>>    while (true) {
>>      while (DC->isRecord() || DC->isTransparentContext())
>>        DC = DC->getParent();
>>
>>      LookupQualifiedName(Previous, DC);
>>
>>      // TODO: decide what we think about using declarations.
>>      if (isLocal || !Previous.empty())
>>        break;
>>
>>      if (isTemplateId) {
>>        if (isa<TranslationUnitDecl>(DC)) break;
>>      } else {
>>        if (DC->isFileContext()) break;
>>      }
>>      DC = DC->getParent();
>>    }
>>
>> There doesn't seem to be any possibility that DC->Equals(CurContext)
>> after this loop, since friends can only be declared in records; in any
>> case the error given only makes sense in a record context anyway. (The
>> same check is also present in another branch, but that one is OK since
>> it involves qualified names.)
>>
>> Please let me know if I am correct and if this is OK to be patched.
>
> I agree with your analysis.  Assuming that it doesn't change any test cases,
> feel free to take it out.
>
> John.