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General GCC Support Notes

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

  • Windows
    • GCC 2.95.x.
    • GCC  3.2.x.
    • GCC  3.3.x.
    • GCC  3.4.x.
    • GCC 4.0.x
    • GCC 4.1.x
    • GCC 4.2.x
    • GCC 4.3.x
    • GCC 4.4.x
    • GCC 4.5.x
    • GCC 4.6.x
    • GCC 4.7.x
    • GCC 4.8.x (x86 and x86-64)
    • GCC 4.9.x (x86 and x86-64)
    • GCC 5.x (x86 and x86-64)
    • GCC 6.x (x86 and x86-64)
  • Linux
    • GCC 2.9.x
    • GCC 3.2.x
    • GCC 3.3.x (x86 and x86-64)
    • GCC 3.4.x (x86 and x86-64)
    • GCC 4.0.x (x86 and x86-64)
    • GCC 4.1.x (x86 and x86-64)
    • GCC 4.2.x (x86 and x86-64)
    • GCC 4.3.x (x86 and x86-64)
    • GCC 4.4.x (x86 and x86-64)
    • GCC 4.5.x (x86 and x86-64)
    • GCC 4.6.x (x86 and x86-64)
    • GCC 4.7.x (x86 and x86-64)
    • GCC 4.8.x (x86 and x86-64)
    • GCC 4.9.x (x86 and x86-64)
    • GCC 5.x (x86 and x86-64)
    • GCC 6.x (x86 and x86-64)
  • GCC-based cross-compilers listed in Embedded Platforms and Cross-Compilers
  • Other GCC-based cross-compilers and custom GCC compiler builds based on GCC compiler versions listed above. Heavily modified GCC-based compilers, as well as their non-standard extensions, may not be supported.

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


Tip

In some versions of CygwinTM (for Windows), it is possible to have GCC 2.95.x and GCC 3.x installed at the same time. This is because there are two differently-named executables for GCC 2.95.x and GCC 3.x, so both of them can be located on the $PATH and both will be detected by C++test.

Unsupported Compiler Extensions for GCC Compilers

The following sections detail the GCC compiler extensions that C++test does not currently support. http://gcc.gnu.org/onlinedocs was used as the source of information on GNU compiler extensions.

These limitations also apply to appropriate versions of GCC-based cross-compilers listed in  Embedded Platforms and Cross-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

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

    Complex Numbers

  • Nested Functions
  • Named Return Values
  • Virtual Functions With Overridden Return Types

    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

    void fatal () __attribute__ ((noreturn));
    void fatal () { }
    typedef void voidfn ();
    volatile voidfn fatal;
      "void fatal()"
  • Member Access Checking

    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

    void tester (int len, char data[len][len])
    {
    }
  • Complex Numbers
  • Nested Functions
  • Named Return Values
  • Virtual Functions With Overridden Return Types

    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

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

Incompatibilities

  • Function Attributes

    void fatal () __attribute__ ((noreturn));
    void fatal () { }
    typedef void voidfn ();
    volatile voidfn fatal;
     "void fatal()"
  • Member Access Checking

     class A
    {
    	public:
    		void pub_func();
    	protected:
    		void prot_func();
    };
    class B : public A
    {
    	public:
    		void foo()
    		{
    			&A::prot_func;
    		}
    };
  • Attributes After Declarator

    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

     void tester (int len, char data[len][len])
    {
    }
  • Complex Numbers
  • Nested Functions
  • Named Return Values
  • Virtual Functions With Overridden Return Types

     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

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

Incompatibilities

  • Function Attributes

    void fatal () __attribute__ ((noreturn));
    void fatal () { }
    typedef void voidfn ();
    volatile voidfn fatal;
  • Member Access Checking

    class A
    {
    public:
    void pub_func();
    protected:
    void prot_func();
    };
    class B : public A
    {
    public:
    void foo()
    {
    &A::prot_func;
    }
    };
  • Attributes After Declarator

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

GCC 3.4.x

Unsupported Features

  • Arrays of Variable Length as Arguments to Functions

    void tester (int len, char data[len][len])
    {
    }
  • Complex Numbers
  • Nested Functions
  • Named Return Values
  • Virtual Functions With Overridden Return Types

    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

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

Incompatibilities

  • Function Attributes

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

GCC 4.0.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 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.
    		}
    	};
    }

GCC 4.1.x

Same as for GCC 4.0.x.

GCC 4.2.x

Same as for GCC 4.0.x.

GCC 4.3.x

Same as for GCC 4.0.x

GCC 4.4.x

Same as for GCC 4.0.x

GCC 4.5.x

Same as for GCC 4.0.x

GCC 4.6.x

Same as for GCC 4.0.x

GCC 4.7.x

Same as for GCC 4.0.x

GCC 4.8.x

Same as for GCC 4.0.x

GCC 4.9.x

Same as for GCC 4.0.x

GCC 5.x

Same as for GCC 4.0.x.

GCC 6.x

Same as for GCC 4.0.x

Missing C++17 features:

N4295 Folding expressions

P0036R0 Unary Folds and Empty Parameter Packs

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