Date: Mon, 22 May 2023 10:10:22 -0700
On Monday, 22 May 2023 04:22:18 PDT Edward Catmur via Std-Proposals wrote:
> Anyway, the point (nowadays) is optimization - the compiler can assume that
> opaque code does not modify a const object (or subobject).
Actually, it's the opposite. Compilers assume that const objects can be
modified through const_cast all the time...
Note how they all reload from memory: https://gcc.godbolt.org/z/YEnzMr8xP.
Even if the member itself is const: https://gcc.godbolt.org/z/xs7xhE5os
I've been meaning to ask for a [[really_const]] attribute for a while.
> Anyway, the point (nowadays) is optimization - the compiler can assume that
> opaque code does not modify a const object (or subobject).
Actually, it's the opposite. Compilers assume that const objects can be
modified through const_cast all the time...
Note how they all reload from memory: https://gcc.godbolt.org/z/YEnzMr8xP.
Even if the member itself is const: https://gcc.godbolt.org/z/xs7xhE5os
I've been meaning to ask for a [[really_const]] attribute for a while.
-- Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org Software Architect - Intel DCAI Cloud Engineering
Received on 2023-05-22 17:10:30