Re: [PATCH RFA] -Wdangling-pointer: fix MEM_REF handling [PR109514]

[Jason Merrill <jason@redhat.com>]

On 4/14/23 21:22, Jeff Law wrote:
> 
> 
> On 4/14/23 17:42, Jason Merrill via Gcc-patches wrote:
>> Tested x86_64-pc-linux-gnu, ok for trunk?
>>
>> -- 8< --
>>
>> Here we hit the MEM_REF case, with its arg an ADDR_EXPR, but had no 
>> handling
>> for that and wrongly assumed it would be a reference to a local variable.
>> This patch overhauls the logic for deciding whether the target is 
>> something
>> to warn about so that we only warn if we specifically recognize the 
>> target
>> as non-local.  None of the existing tests regress as a result.
>>
>>     PR c++/109514
>>
>> gcc/ChangeLog:
>>
>>     * gimple-ssa-warn-access.cc (pass_waccess::check_dangling_stores):
>>     Overhaul lhs_ref.ref analysis.
>>
>> gcc/testsuite/ChangeLog:
>>
>>     * g++.dg/warn/Wdangling-pointer-6.C: New test.
> One might ask if we have a (MEM_REF (ADDR_REF ...)) why we didn't 
> simplify that by removing the MEM_REF and ADDR_REF wrappers.

FYI in this case the type of the MEM_REF is the type of a member of a 
member of a member of the variable.

> But on 
> the assumption there's a good reason to have such nodes, OK for the trunk.
> 
> jeff
>