Error Message
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()
{
}