On Tuesday, January 13, 2026, Thiago Macieira wrote:
>
>
> Then:
>
> if (auto x = SomeFunction) return !x;
>



I'm assuming you meant SomeFunction().

SomeFunction could return an Lvalue, a PRvalue, or an Xvalue, for example:

    mutex SomeFunction(void);
    mutex &SomeFunction(void);
    mutex &&SomeFunction(void);

This is why we need:

    decltype(SomeFunction) x = SomeFunction();
    if ( x ) return !x;

And so the problem is that you need to type out the expression twice, give
the variable a non-clashing name, and mention the variable's name twice as
well.

Much easier to mention the function only once and to not mention the
variable at all.