error: declaration does not declare anything [-Werror]| - c

Question

typedef struct BO2Offsets
{
struct Prestige
{
u32 offset = 0x000000;
char data[13] = { 0x00, 0x01, 0x02, 0x03, 0x04,
0x05, 0x06, 0x07, 0x08, 0x09,
0x0A, 0x0B, 0x0C
};
};
} BO2Offsets;
This is a very amateur question with what I'm sure is going to be a very simple answer, but I can't resolve the problem. I have a .h file with his corresponding .cpp file, but for some reason whenever I try to compile with gcc, I keep getting errors:
declaration does not declare anything // line 10
expected ':', ',', ';', '}' or 'attribute' before '=' token // line 5
I would like use BO2Offsets like that:
BO2Offsets BO2;
BO2.Prestige.offset;
EDIT2:
Resolved, thank's :)
typedef struct BO2Offsets BO2Offsets;
struct BO2Offsets
{
struct Prestige
{
u32 offset;
char data[13];
} prestige;
};

Answer 1

You are probably using C compiler, but the code is C++ (that too C++14). You need to change the compiler (or toolset), or change the code so that it compiles with C compiler.
EDIT: Which line? Does it say struct Prestige is not utilized?
Based on your edit:
typedef struct Prestige
{
u32 offset = 0x000000;
char data[13] = { 0x00, 0x01, 0x02, 0x03, 0x04,
0x05, 0x06, 0x07, 0x08, 0x09,
0x0A, 0x0B, 0x0C
};
} prestige; // Small letters
...
BO2Offsets BO2;
BO2.prestige.offset;
I've used small letters for the variable, so that it is clearly different from the type Prestige.