Inline function linkage

by

When the function in the header is not inline, then multiple definitions of this function (e.g. in multiple translation units) is a violation of ODR rules.

Inline functions by default have external linkage. Hence, as a consequence of ODR rules (given below), such multiple definitions (e.g. in multiple translation units) are Okay:

$3.2/5- “There can be more than one
definition of a class type (Clause 9),
enumeration type (7.2), inline
function with external linkage
(7.1.2), class template (Clause 14),
non-static function template (14.5.6),
static data member of a class template
(14.5.1.3), member function of a class
template (14.5.1.1), or template
specialization for which some template
parameters are not specified (14.7,
14.5.5) in a program provided that each definition appears in a different
translation unit, and provided the
definitions satisfy the following
requirements. Given such an entity
named D defined in more than one
translation unit, then

— each definition of D shall consist
of the same sequence of tokens; and […]

How the linker treats inline functions is a pretty much implementation level detail. Suffice it to know that the implementation accepts such mulitple defintions within the limitations of ODR rules

Note that if the function declaration in header is changed to ‘static inline….’, then the inline function explicitly has internal linkage and each translation unit has it’s own copy of the static inline function.

More Related Contents:

  1. C++ inline member function in .cpp file
  2. Is there still a use for inline? [duplicate]
  3. Calling function in string.h file without object
  4. New to programming: How to call a structure’s variables in a function and then update them? (C++) [closed]
  5. Compilation error: expected constructor, destructor, or type conversion before ‘;’ token [closed]
  6. Return array in a function
  7. Using generic std::function objects with member functions in one class
  8. C++ callback using class member
  9. How to make a .lib file when have a .dll file and a header file
  10. C++ return array from function [duplicate]
  11. Why doesn’t C++ support functions returning arrays?
  12. Should I use an exception specifier in C++?
  13. When to Overload the Comma Operator?
  14. Why can’t we pass arrays to function by value?
  15. ‘foo’ was not declared in this scope c++
  16. Stack overflow caused by recursive function
  17. C++ inlining class methods causes undefined reference
  18. Function pointer vs Function reference
  19. std::bind a bound function
  20. How Non-Member Functions Improve Encapsulation
  21. Do class functions/variables have to be declared before being used?
  22. How will i know whether inline function is actually replaced at the place where it is called or not?
  23. how do I make a portable isnan/isinf function
  24. Function in C++ returns by value or by reference?
  25. Function to mangle/demangle functions
  26. How much overhead is there in calling a function in C++?
  27. is it possible to make function that will accept multiple data types for given argument?
  28. Get signatures of exported functions in a DLL
  29. Can I treat a specific warning as an error?
  30. Why can’t C++11 move a noncopyable functor to a std::function?

Leave a Comment