Hi, and thank you for responding!

To your question, Rhidian, my idea was to remove the function call at compile-time and throw an error if the function is non-void or not ignored with std::ignore.
But the idea of decorating the function with something like "[[ ... ]]" could be used for a multitude of purpose, and cannot be a template-syntax or a reflection. Call it a "Decorator"?
And that sounds like a pretty big thing that would/should cover a lot more than simply removing a function call.

Your case of runtime-decision making, Pavel, is something I had not thought of. It sounds really cool, but I was only thinking about compile-time.

Tiago:
I can't think out of my head what other uses there would be. Probably someone out there needs something like this for something, but that sounds like a big if.
So probably not worth the trouble, no.

Just read Rainer Deyke's no. email, which pretty much settles it with a convincing argument, as I was writing this.

Thank you for entertaining this idea.
Best,
Alexander

Fra: Pavel Vazharov <freakpv@gmail.com>
Sendt: 28. oktober 2026 10:10
Til: std-proposals@lists.isocpp.org <std-proposals@lists.isocpp.org>
Cc: Alexander Christensen <alex_c007@hotmail.com>
Emne: Re: [std-proposals] Modularized logging library - prevent parameter evaluation before calling
 
Hi,
 
In my ideal world, I could define my logging function like this:
[[ConditionalDiscard = IsShipping()]]
template<typename... Ts>
void LogWarn(std::string_view fmt, Ts&&... args) { /* ... */ }

I assume the function IsShipping() to be constexpr.
And the effect would be a function call completely stripped 

What about the other cases where the decision for logging based on the log level is taken at runtime?
For example, I've worked with systems where the logging level for a given sub-system of the application (or the whole application) can be changed at runtime and this helps collect more information about specific production issues. 
However, we still wanted lazy evaluation of the parameters because these logs are still disabled 99% of the time.
We used macros for our logging systems. At least I don't know a better alternative for this.

Regards,
Pavel.