GNU GCC

Modules
	Variable Attributes
	Function Attributes
	Built-in Functions

Macros
#define	ALIGN_OF(x)   __alignof__(x)
#define	ATTR_SECTION(sec_name)   __attribute__ (( section(#sec_name) ))
	Normally, the compiler places the objects it generates in sections like data or bss & function in text. Sometimes, however, you need additional sections, or you need certain particular variables to appear in special sections, for example to map to special hardware. The section attribute specifies that a variable (or function) lives in a particular section.
#define	ATTR_ERROR(Message)   __attribute__ ((error(Message)))
	If this attribute is used on a function declaration and a call to such a function is not eliminated through dead code elimination or other optimizations, an error that includes message is diagnosed. This is useful for compile-time checking.
#define	ATTR_WARNING(Message)   __attribute__ ((warning(Message)))
	If this attribute is used on a function declaration and a call to such a function is not eliminated through dead code elimination or other optimizations, a warning that includes message is diagnosed. This is useful for compile-time checking.

Detailed Description