The option `-traditional' disables certain keywords; `-ansi'
disables certain others. This causes trouble when you want to use GNU C
extensions, or ANSI C features, in a general-purpose header file that
should be usable by all programs, including ANSI C programs and traditional
ones. The keywords asm, typeof and inline cannot be
used since they won't work in a program compiled with `-ansi', while
the keywords const, volatile, signed, typeof
and inline won't work in a program compiled with
`-traditional'.
The way to solve these problems is to put `__' at the beginning and
end of each problematical keyword. For example, use __asm__
instead of asm, __const__ instead of const, and
__inline__ instead of inline.
Other C compilers won't accept these alternative keywords; if you want to compile with another compiler, you can define the alternate keywords as macros to replace them with the customary keywords. It looks like this:
#ifndef __GNUC__ #define __asm__ asm #endif
`-pedantic' causes warnings for many GNU C extensions. You can
prevent such warnings within one expression by writing
__extension__ before the expression. __extension__ has no
effect aside from this.