TASKING VX-toolset for ARM User Guide

C++ Language2.3. GNU ExtensionsThe C++ compiler can be configured to support the GNU C++ mode (command line option --g++). In thismode, many extensions provided by the GNU C++ compiler are accepted. The following extensions areprovided in GNU C++ mode.• Extended designators are accepted• Compound literals are accepted.• Non-standard anonymous unions are accepted• The typeof operator is supported. This operator can take an expression or a type (like the sizeofoperator, but parentheses are always required) and expands to the type of the given entity. It can beused wherever a typedef name is allowedtypeof(2*2.3) d; // Declares a "double"typeof(int) i; // Declares an "int"This can be useful in macro and template definitions.• The __extension__ keyword is accepted preceding declarations and certain expressions. It has noeffect on the meaning of a program.__extension__ __inline__ int f(int a) {return a > 0 ? a/2 : f(__extension__ 1-a);}• In all GNU C modes and in GNU C++ modes with gnu_version < 30400, the type modifiers signed,unsigned, long and short can be used with typedef types if the specifier is valid with the underlyingtype of the typedef in ANSI C. E.g.:typedef int I;unsigned I *pui; // OK in GNU C++ mode;// same as "unsigned int *pui"• If the command line option --long-long is specified, the extensions for the long long and unsignedlong long types are enabled.• Zero-length array types (specified by [0]) are supported. These are complete types of size zero.• C99-style flexible array members are accepted. In addition, the last field of a class type have a classtype whose last field is a flexible array member. In GNU C++ mode, flexible array members are treatedexactly like zero-length arrays, and can therefore appear anywhere in the class type.• The C99 _Pragma operator is supported.• The gcc built-in and facilities (__builtin_va_list, __builtin_va_arg, ...) areaccepted.• The sizeof operator is applicable to void and to function types and evaluates to the value one.41