[naikrovek]

Function calls have an overhead, and if the function is only used once it makes no sense to break it out.

It also makes no sense to have a rule on the maximum number of lines for a function. These rules are often created by people who don't write software that needs to have high performance.

[TravHatesMe]

The compiler does a lot of optimizing, including inlining function calls so that they do not have overhead. My opinion is to favour readable and maintainable code. If there is a performance issue, then profile it, measure and then optimize. No need to prematurely optimize at the cost of code quality.

[kryptiskt]

A function that is called once will always be inlined. Trust the compiler.

[MauranKilom]

> A function that is called once will always be inlined.

That is objectively false. Even though I agree with the spirit. For starters, unoptimized builds won't have that. Second, exceptions tend to inhibit inlining. Compare https://godbolt.org/z/c8Jayf with https://godbolt.org/z/Uoo2YA. Third, it's easy enough to push one of the heuristics used for inlining high enough in the wrong direction (e.g. function size). I recommend the clang optimizer view on godbolt.

Also note that it can be hard for a compiler to prove that a function is not used outside the current translation unit (although anonymous namespaces help with that). Number of calls is only one of the heuristics for inlining though anyway.

[naikrovek]

All languages? No.

Compilers are plenty stupid, and have not earned blind trust.