Re: [RFC PATCH] c++, gimplify: Implement C++26 P2795R5 - Erroneous behavior for uninitialized reads [PR114457]

[Qing Zhao]

> On Sep 18, 2025, at 17:42, Jason Merrill <ja...@redhat.com> wrote:
> 
> On 9/18/25 10:52 PM, Qing Zhao wrote:
>>> On Sep 17, 2025, at 12:08, Jakub Jelinek <ja...@redhat.com> wrote:
>>> 
>>> Hi!
>>> 
>>> -ftrivial-auto-var-init= also calls .DEFERRED_INIT for temporaries
>>> if they have VOID_TYPE_P TARGET_EXPR_INITIAL (otherwise they are expanded
>>> as INIT_EXPR of the TARGET_EXPR_SLOT and TARGET_EXPR_INITIAL and so
>>> everything is initialized; trying to emit .DEFERRED_INIT in such a case
>>> breaks a lot of stuff because e.g. const vars turned into static but
>>> not static when .DEFERRED_INIT is done will try to write into .rodata).
>> A little confused with the above. Do you mean that not all temporaries are 
>> initialized to zero, only
>> the temporaries that have VOID_TYPE_P TARGET_EXPR_INITIAL are initialized to 
>> zero?
> 
> Temporaries with non-void INITIAL are initialized to that value, so there's 
> no need to also initialize them to zero.

Okay, I see.
thanks.
Qing
> 
> Jason