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GCC_Support
GCC_Support
General GCC Support Notes

C/C++test supports the following distributions of the GCC compiler:

...

To use any of these supported distributions, the directory containing the GCC executable must be included in the $PATH environment variable.

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Tip

...

.

Unsupported Compiler Extensions for GCC Compilers

...

These limitations also apply to appropriate versions of GCC-based cross-compilers listed in Supported Compilers, other GCC-based cross-compilers, and custom GCC compiler builds.

GCC 2.95.x

Unsupported Features

  • Arrays of Variable Length as Arguments to Functions

    Code Block
    void tester (int len, char data[len][len])
{
}

    Complex Numbers

  • Nested Functions
  • Named Return Values

  • Virtual Functions With Overridden Return Types

    Code Block
    class A
{
	public:
		virtual void* a();
};
class B:
	public A
{
	public:
		virtual B* a(); // Return type changed from void* to
			(compatible) B*.
};

Incompatibilities

  • Function Attributes

    Code Block
    void fatal () __attribute__ ((noreturn));
void fatal () { }
typedef void voidfn ();
volatile voidfn fatal;
  "void fatal()"

  • Member Access Checking

    Code Block
    class A
{
	public:
		void pub_func();
	protected:
		void prot_func();
};
class B : public A
{
	public:
		void foo()
		{
			&A::prot_func;
		}
};

GCC 3.2.x

Unsupported Features

  • Arrays of Variable Length as Arguments to Functions

    Code Block
    void tester (int len, char data[len][len])
{
}
  • Complex Numbers
  • Nested Functions
  • Named Return Values

  • Virtual Functions With Overridden Return Types

    Code Block
    class A
{
	public:
		virtual void* a();
};
class B:
	public A
{
	public:
		virtual B* a(); // Return type changed from void* to
			(compatible) B*.
};
  • Java Extensions (like extern "Java", java attributes)

  • Restricting Pointer Aliasing for Member Functions

    Code Block
    class T
{
	public:
		void fn();
};
void T::fn () __restrict__
{
}

Incompatibilities

  • Function Attributes

    Code Block
    void fatal () __attribute__ ((noreturn));
void fatal () { }
typedef void voidfn ();
volatile voidfn fatal;
 "void fatal()"

  • Member Access Checking

    Code Block
     class A
{
	public:
		void pub_func();
	protected:
		void prot_func();
};
class B : public A
{
	public:
		void foo()
		{
			&A::prot_func;
		}
};

  • Attributes After Declarator

    Code Block
    class X
{
	public:
		X(int) {}
};
X x(1) __attribute__((aligned (16)));

GCC 3.3.x

Unsupported Features

  • Arrays of Variable Length as Arguments to Functions

    Code Block
     void tester (int len, char data[len][len])
{
}
  • Complex Numbers
  • Nested Functions
  • Named Return Values

  • Virtual Functions With Overridden Return Types

    Code Block
     class A
{
	public:
		virtual void* a();
};
class B:
	public A
{
	public:
		virtual B* a(); // Return type changed from void* to
			(compatible) B*.
};
  • Java Extensions (like extern "Java", java attributes)

  • Restricting Pointer Aliasing for Member Functions

    Code Block
     class T
{
	public:
		void fn();
};
void T::fn () __restrict__
{
}

Incompatibilities

  • Function Attributes

    Code Block
    void fatal () __attribute__ ((noreturn));
void fatal () { }
typedef void voidfn ();
volatile voidfn fatal;

  • Member Access Checking

    Code Block
    class A
{
public:
void pub_func();
protected:
void prot_func();
};
class B : public A
{
public:
void foo()
{
&A::prot_func;
}
};

  • Attributes After Declarator

    Code Block
    class X
{
public:
X(int) {}
};
X x(1) __attribute__((aligned (16)));

...

.

...

Unsupported Features

  • Arrays of Variable Length as Arguments to Functions

    Code Block
    void tester (int len, char data[len][len])
{
}
  • Complex Numbers
  • Nested Functions
  • Named Return Values

  • Virtual Functions With Overridden Return Types

    Code Block
    class A
{
	public:
		virtual void* a();
};
class B:
	public A
{
	public:
		virtual B* a(); // Return type changed from void* to
			(compatible) B*.
};
  • Java Extensions (like extern "Java", java attributes)

  • Restricting Pointer Aliasing for Member Functions

    Code Block
    class T
{
	public:
		void fn();
};
void T::fn () __restrict__
{
}

Incompatibilities

Function Attributes

...

GCC 4.0.x

Unsupported Features

  • Arrays of Variable Length as Arguments to Functions

    Code Block
    void tester (int len, char data[len][len])
{
}
  • Complex Numbers
  • Nested Functions

  • Virtual Function With Overridden Return Type

    Code Block
    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

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

Incompatibilities

  • Function Attributes

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

  • Friend Declarations

    Code Block
    class A;
namespace N {
	class B {
		friend class A; // In GCC 4.0+ it refer to N::A (which has not been
			// declared yet) But EDG and older GCCs refer to ::A
		int _private;
};
	class A {
		void foo()
		{
			B b;
			b._private = 0; // EDG inaccessible field.
		}
	};
}

...