[PATCH RFA] cgraph: flatten and same_body aliases [PR96078]

[Jason Merrill]

On 2/16/21 1:52 PM, Jeff Law wrote:
> 
> 
> On 2/11/21 10:18 PM, Jason Merrill via Gcc-patches wrote:
>> The patch for PR92372 made us start warning about a flatten attribute on an
>> alias.  But in the case of C++ 'tor base/complete variants, the user didn't
>> create the alias, so we shouldn't warn.
>>
>> I could also remove the attribute in maybe_clone_body, but here seems a bit
>> better.
>>
>> Tested x86_64-pc-linux-gnu.  OK for trunk?
>>
>> gcc/ChangeLog:
>>
>> 	PR c++/96078
>> 	* cgraph.c (cgraph_node::create_same_body_alias): Remove flatten
>> 	attribute from alias.
>>
>> gcc/testsuite/ChangeLog:
>>
>> 	PR c++/96078
>> 	* g++.dg/ext/attr-flatten1.C: New test.
> But shouldn't we validate that we've got a C++ ctor/dtor rather than
> blindly removing the attribute from all aliases?  ISTM like the patch
> as-is would always suppress warnings when we create a same-body alias
> regardless of why we created a same-body alias.

Fair enough.  How about this approach, instead?  If the target also has 
attribute flatten, we're getting the desired effect even though the 
called symbol is an alias.
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