What Does It Mean For a C++ Function To Be Inline?

Question

See title: what does it mean for a C++ function to be inline?

Answer 1

@OldMan

The compilers only inline non marked as inline functions ONLY if you request it to do so.

Only if by "request" you mean "turn on optimizations".

Its correct only on the effcts nto the casuse.

It's correct in both.

Inline do not generate any extra info that the linker may use. Compiel 2 object files and check. It allow multiple definitions exaclty because the symbols are not exported! Not because that is its goal!

What do you mean, "the symbols are not exported"? inline functions are not static. Their names are visible; they have external linkage. To quote from the C++ Standard:

void h(); inline void h(); // external linkage

inline void l(); void l(); // external linkage

The multiple definitions thing is very much the goal. It's mandatory:

An inline function shall be defined in every translation unit in which it is used and shall have exactly the same definition in every case (3.2). [Note: a call to the inline function may be encountered before its definition appears in the translation unit. ] If a function with external linkage is declared inline in one translation unit, it shall be declared inline in all translation units in which it appears; no diagnostic is required. An inline function with external linkage shall have the same address in all translation units.