No function described in Clause [input.output] except for
causes any instance of
to be called.
If any user function called from a function declared in Clause [input.output] or
as an overriding virtual function of any class declared in Clause [input.output]
the behavior is undefined.
In the classes of Clause [input.output], a template parameter with name
charT represents a member of the set of types containing char, wchar_t,
and any other implementation-defined
character types that satisfy the requirements for a character on which any of
the iostream components can be instantiated.
If one thread makes a library call a that writes a value to a stream
and, as a result, another thread reads this value from the stream through a
library call b such that this does not result in a data race, then
a's write synchronizes with