gcc_extensions

Controls the acceptance of GNU C language extensions.

  #pragma gcc_extensions on | off | reset  

If you enable this pragma, the compiler accepts GNU C extensions in C source code. This includes the following non-ANSI C extensions:

• Initialization of automatic struct or array variables with non- const values. The following listing provides an example.
  Listing: Example of Array Initialization with a Non-const Value

  int foo(int arg)
  
  {
  
  
  
      int arr[2] = { arg, arg+1 };
  
  
  
  }

• sizeof(void)==1
• sizeof(function-type)==1
• Limited support for GCC statements and declarations within expressions. The following listing provides an example.
  Listing: Example of GCC Statements and Declarations Within Expressions

  #pragma gcc_extensions on
  
  #define POW2(n) ({ int i,r; for(r=1,i=n; i>0; --i) r<<=1; r;})
  
  
  
  int main()
  
  
  
  {
  
  
  
      return POW2(4);
  
  
  
  }

  This feature only works for expressions in function bodies.

• Macro redefinitions without a previous #undef.
• The GCC keyword typeof.

This pragma does not correspond to any setting in the Language panel. To check the global optimizer, use __option (gcc_extensions), described in Checking Pragma Settings. By default, this pragma is disabled.