Mysterious undefined reference error

[helios]

This is what my setup looks like:

A.h

#pragma once

extern const byte_t packed_image_data[221120];
extern const std::uint16_t tile_mapping[24035];
static const size_t packed_image_data_size = 221120;
static const size_t tile_mapping_size = 24035;

B.inl

const byte_t packed_image_data[] = { /*...*/ };
const std::uint16_t tile_mapping[] = { /*...*/ };

B.cpp

#include "B.inl" 

And the errors:

1>Renderer.obj : error LNK2001: unresolved external symbol "unsigned char const * const packed_image_data" (?packed_image_data@@3QBEB)
1>Renderer.obj : error LNK2001: unresolved external symbol "unsigned short const * const tile_mapping" (?tile_mapping@@3QBGB)

I really don't understand why this isn't working. I do the exact same thing for other data arrays and it works fine. I can get it to link if I move the include directive to Renderer.cpp, but I just want to understand what I'm doing wrong. Looking at the generated .obj, I can see that the string "packed_image_data" does not appear anywhere, which would suggest the compiler has chosen not to generate a symbol for it, even though I can see the data is actually there. So I'm just stumped.

[ne555]

https://stackoverflow.com/questions/2190919/mixing-extern-and-const
in B.inl #include "A.h"

looking through `nm', in changes from `r' to `R'

object file format. If lowercase, the symbol is usually local; if uppercase, the symbol is global (external).

[helios]

It also works to use extern at the site of definition. But why is this necessary only for const globals?

[ne555]

seems that const implies static
https://stackoverflow.com/a/178259

[helios]

Ah, I see. Alright, that answers my question, thanks.