5.7.3 Options for Controlling the C Dialect

The options tabulated below define the type of C dialect used by the compiler and are discussed in the sections that follow.

Table 5-8. C Dialect Control Options
Option	Definition
`-ansi`	Support all (and only) ANSI-standard C programs.
`-aux-info filename`	Generates function prototypes from a C module, placing the output in a file with the specified name.
`-f[no-]freestanding`	Asserts that the project will be built for a freestanding (as opposed to a hosted) environment.
`-f[no-]asm`	Restricts the recognition of certain keywords, freeing them to be used as identifiers.
`-fno-builtin` `-fno-builtin-function`	Don’t recognize built-in functions that do not begin with `__builtin_` as prefix.
`-f[no-]unsigned-char` `-f[no-]signed-char`	Changes the signedness of a plain `char` type.
`-f[no-]signed-bitfields` `-f[no-]unsigned-bitfields`	Changes the signedness of a plain int bit-field. By default, such a bit field is signed.