General GCC Support Notes

See GNU GCC for the list of supported GCC-based compilers.
You can use a custom GCC compiler build that is based on one of the the supported GCC compilers. However, heavily modified GCC-based compilers or non-standard compiler extensions may not be supported.
To use a GCC-based compiler, ensure that the directory that contains the GCC executable is included in the $PATH environment variable.

Unsupported Compiler Extensions for GCC Compilers

The following sections specifies the GCC compiler extensions that are not supported by C/C++test. The limitations apply to the supported GCC-based compilers, as well as custom GCC compiler builds. See http://gcc.gnu.org/onlinedocs for more information about GNU compiler extensions.

GCC 5.x

Unsupported Features

Arrays of Variable Length as Arguments to Functions
void tester (int len, char data[len][len]) { }
Complex Numbers
Nested Functions

Virtual Function With Overridden Return Type

class A
{
	public:
		virtual void* a();
};
class B:
	public A
{
	public:
		virtual B* a(); // Return type changed from void* to (compatible) B*.
			// It is ok in GCC but EDG will complain
};

Java Extensions (like extern "Java", java attributes)
Offsetof extension

Restricting Pointer Aliasing for Member functions

class T
{
	public:
		void fn();
};
void T::fn () __restrict__ // EDG won't compile this
{
}

Incompatibilities

Function Attributes

void fatal () __attribute__ ((noreturn));
void fatal () { }
typedef void voidfn ();
volatile voidfn fatal; // EDG: declaration is incompatible with
// "void fatal()"

Friend Declarations

class A;
namespace N {
	class B {
		friend class A; // In GCC it refers to N::A (which has not been
			// declared yet), but EDG refers to ::A
		int _private;
};
	class A {
		void foo()
		{
			B b;
			b._private = 0; // EDG inaccessible field.
		}
	};
}

GCC 6.x

Same as for GCC 5.x.