General GCC Support Notes

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

• Windows
  • 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)
  • GCC 7.x (x86 and x86-64)
• Linux
  • 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 7.x (x86 and x86-64)
• GCC-based cross-compilers listed in 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.

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 Compilers, other GCC-based cross-compilers, and custom GCC compiler builds.

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

GCC 7.x

Same as for GCC 4.0.x

Missing C++17 features:

• N4295 Folding expressions
• P0036R0 Unary Folds and Empty Parameter Packs
• P0017R1 Extension to aggregate initialization
• P0091R4 Template argument deduction for class templates
• P0127R2 Declaring non-type template parameters with auto
• P0135R1 Guaranteed copy elision
• P0136R1 Rewording inheriting constructors (core issue 1941 et al)
• P0145R3 Refining Expression Evaluation Order for Idiomatic C++
• P0195R2 Pack expansions in using-declarations
• P0522R0 DR 150, Matching of template template arguments