On Monday, 10 March 2025 15:59:20 Pacific Daylight Time Tom Honermann via Std-
Proposals wrote:
> > When you build it again it is technically a new build time, right?
>
> How is that different from the status quo given the existence of
> __TIME__, __DATE__, and __FILE__ (for relocatable builds)?

(reproducible)

It isn't. That's why I'm arguing that, if we are to have this feature —which I
oppose— then it should be implemented using a preprocessor token so the
behaviour is exactly the same as that of __TIME__:

If any of the source files or headers that your build tool tracks has changed,
it will start a new compilation. This will cause the preprocessed output to be
different, which means the cache lookup will be a miss, and leading the cache
tool to execute the actual compiler, thus giving you a new object file and a
new binary.

I do note you can already do this with command-line options:
  -DUNIXTIME=$(date +%s)

But this is harder to find and fix for reproducibility than a compiler feature.
So if there is sufficient interest in this feature, I would prefer it be in the
compiler.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Principal Engineer - Intel DCAI Platform & System Engineering