16 Library introduction [library]

16.4 Library-wide requirements [requirements]

16.4.6 Conforming implementations [conforming]

16.4.6.9 Reentrancy [reentrancy]

Except where explicitly specified in this document, it is implementation-defined which functions in the C++ standard library may be recursively reentered.
During the execution of a standard library non-static member function F on an object, if that object is accessed through a glvalue that is not obtained, directly or indirectly, from the object parameter of F, in a manner that can conflict ([intro.races]) with any access that F is permitted to perform ([res.on.data.races]), the behavior is undefined unless otherwise specified.