Re: cc1plus: note: source object is likely at address zero

On Thu, 5 Mar 2026 at 13:34, Andrew C Aitchison via Gcc-help
<[email protected]> wrote:
> That godbolt link uses options
>         -stdc=c++23 -O1 -Wall
> but I get the same output with
>         -std=c++11 -Og -Wstringop-overread
> but with "-O0" or with no -O option at all the warning disappears.

That's expected, the warning is based on data flow analysis that
happens during optimization. If you disable all the optimization
passes, you don't get those warnings.

This is documented: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html

"The effectiveness of some warnings depends on optimizations also
being enabled. For example, -Wsuggest-final-types is more effective
with link-time optimization. Some other warnings may not be issued at
all unless optimization is enabled. While optimization in general
improves the efficacy of warnings about control and data-flow
problems, in some cases it may also cause false positives. "