cmake: Skip superfluous PIC/PIE warning for Windows

[hebasto]

PIC/PIE is not a thing in Windows PE format. Therefore, warnings are rather making noise than providing valuable feedback.

[hebasto]

Rebased.

[theuni]

It's frustrating that CMake doesn't just know this. It's also frustrating that check_pie_supported seems to just be wrong for Windows? I wonder if we should upstream a fix/change?

FWIW, pic/pie is default on for macOS, so if we're not already getting warnings there, we probably will at some point, so we may as well include that here as well.

[fanquake]

FWIW, pic/pie is default on for macOS,

Was this also always the case for x86_64? I guess starting with arm64, it was just made impossible to disable.

[hebasto]

It's frustrating that CMake doesn't just know this. It's also frustrating that check_pie_supported seems to just be wrong for Windows? I wonder if we should upstream a fix/change?

Sorry if I understood your comment in a wrong way, but it seems that CMake does its job well. On Windows, the check_pie_supported function clearly recognizes that "PIE and NO_PIE are not supported by linker for CXX".

It was our decision to print a warning regardless of its usefulness.

If guarding the whole code block with if(NOT WIN32) looks unclear, maybe do it for message(WARNING ...) only?

[TheCharlatan]

If guarding the whole code block with if(NOT WIN32) looks unclear, maybe do it for message(WARNING ...) only?

That seems preferable to me, maybe also with a small comment explaining why?

[hebasto]

Rebased.

Addressed @TheCharlatan's comment.

[TheCharlatan]

ACK 52447c3

[theuni]

Post-merge ACK. Thanks for the explanation, @hebasto, I had indeed misunderstood.