[Bug preprocessor/59357] no documentation of #pragma once

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59357

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
It is documented in the next page:
http://gcc.gnu.org/onlinedocs/cpp/Alternatives-to-Wrapper-_0023ifndef.html#Alternatives-to-Wrapper-_0023ifndef

Another way to prevent a header file from being included more than once is with
the ‘#pragma once’ directive. If ‘#pragma once’ is seen when scanning a header
file, that file will never be read again, no matter what.

‘#pragma once’ does not have the problems that ‘#import’ does, but it is not
recognized by all preprocessors, so you cannot rely on it in a portable
program.