20 Library introduction [library]

It is unspecified whether any non-member functions in the C++ standard library are defined as inline.

A call to a non-member function signature described in Clauses [language.support] through [thread] and Annex [depr] shall behave as if the implementation declared no additional non-member function signatures.181

An implementation shall not declare a non-member function signature with additional default arguments.

Unless otherwise specified, calls made by functions in the standard library to non-operator, non-member functions do not use functions from another namespace which are found through argument-dependent name lookup ([basic.lookup.argdep]). [ Note: The phrase “unless otherwise specified” applies to cases such as the swappable with requirements ([swappable.requirements]). The exception for overloaded operators allows argument-dependent lookup in cases like that of ostream_­iterator​::​operator=:

Effects:

*out_stream << value;
if (delim != 0)
  *out_stream << delim;
return *this;

 — end note ]