Question

The title say it all. After including <csetjmp>, longjmp and jmp_buf are in the std namespace, but setjmpis not. I verified this on MinGW4.5 and MSVC10. After looking into the <csetjmp> header, I could not figure out the reason of this choice. I was always assuming that every <cheader> file is wrapping a <header.h> in the std namespace.

Am I wrong ? What’s the rationale behind the setjmp special case ? Please enlighten me !

_{Note : I’m aware of the issues of misusing setjmp/longjmp in C++.}

Answer 1

setjmp can be implemented as a macro, so the C++ standard has this to say in 17.6.1.2 [headers]:

Names which are defined as macros in C shall be defined as macros in
the C++ standard library, even if C grants license for implementation
as functions. [ Note: The names defined as macros in C include the
following: assert, offsetof, setjmp, va_arg, va_end, and
va_start. —end note ]

In other words, it’s a macro.