15.1.6 GNU cc Extensions

The GNU cc compiler has several useful extensions, which are documented in the GNU cc manual. A program which must be portable to other C compilers must naturally avoid these extensions; the `-pedantic' option may be used to warn about any accidental use of an extension.

However, the GNU cc compiler is itself highly portable, and it runs on all modern Unix platforms as well as on Windows. Depending upon your portability requirements, you may be able to simply assume that GNU cc is available, in which case your program may use extensions when they are useful. Note that some extensions are inherently non-portable, such as inline assembler code, or using attributes to specify a particular section for a function or a global variable.