Re: jsonapi: scary new warnings with LTO enabled

Jacob Champion <jacob(dot)champion(at)enterprisedb(dot)com> writes:
> On Wed, Apr 16, 2025 at 4:04 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Looking through all of the callers of freeJsonLexContext, quite
>> a lot of them use local JsonLexContext structs, and probably some
>> of them are more performance-critical than these. So that raises
>> the question of why are we seeing warnings for only these call
>> sites?

> Yeah, I had the same question...

After making another pass through the callers of freeJsonLexContext,
I observe that the warnings appear in callers that use a local
variable *and* contain goto statements. So I'm betting that the
presence of goto's causes the LTO optimizer to pull in its horns
quite a bit and thereby fail to detect the flag correlation.

>> Maybe there is a more elegant way to suppress them.

> Can we brute-force ignore this particular warning site with a #pragma
> (suggested in [1])?

That's surely not elegant :-(. However, I don't especially want to
rewrite away the goto's in these callers ...

regards, tom lane