Compiler Warning (level 4) C4201

nonstandard extension used : nameless struct/union

Under Microsoft extensions (/Ze), you can specify a structure without a declarator as members of another structure or union. These structures generate an error under ANSI compatibility (/Za).

Example

// C4201.cpp
// compile with: /W4
struct S
{
   float y;
   struct
   {
      int a, b, c;  // C4201
   };
} *p_s;

int main()
{
}