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The option `-traditional' disables certain keywords;
`-ansi' and the various `-std' options disable certain
others. This causes trouble when you want to use GNU C extensions, or
ISO C features, in a general-purpose header file that should be usable
by all programs, including ISO C programs and traditional ones. The
inline cannot be used
since they won't work in a program compiled with `-ansi'
inline can be used in a program compiled with
`-std=c99'), while the keywords
inline won't work in a program
compiled with `-traditional'. The ISO C99 keyword
restrict is only available when `-std=gnu99' (which will
eventually be the default) or `-std=c99' (or the equivalent
`-std=iso9899:1999') is used.
The way to solve these problems is to put `__' at the beginning and
end of each problematical keyword. For example, use
__const__ instead of
__inline__ instead of
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' and other options cause warnings for many GNU C extensions.
prevent such warnings within one expression by writing
__extension__ before the expression.
__extension__ has no
effect aside from this.