Make GetMonData and GetBoxMonData ABI-safe

[AZero13]

Clang and LLVM hate this, so instead I am doing the manual work of using macros to do the equivalent of a default parameter in C++ to avoid work downstream.

[mrgriffin]

Do we need all these changes? Couldn't it have been more like this in include/pokemon.h?

 u32 GetMonData3(struct Pokemon *mon, s32 field, u8 *data);
-u32 GetMonData2(struct Pokemon *mon, s32 field);
 u32 GetBoxMonData3(struct BoxPokemon *boxMon, s32 field, u8 *data);
-u32 GetBoxMonData2(struct BoxPokemon *boxMon, s32 field);
+#if UBFIX
+#define GetMonData2(mon, field) GetMonData3(mon, field, NULL)
+#define GetBoxMonData2(boxMon, field) GetBoxMonData3(boMon, field, NULL)
+#else
 u32 GetMonData2(struct Pokemon *mon, s32 field);
 u32 GetBoxMonData2(struct BoxPokemon *boxMon, s32 field);
+#endif

And then just the conditional declaration of aliases in src/pokemon.c, i.e. without renaming GetMonData3/GetBoxMonData3.

Also, have you picked UBFIX because on a different (non-ARM) ABI the behavior would be undefined? I don't think it could cause problems on AArch32 unless the functions took 5+ parameters?

[mrgriffin]

How does this work? Aren't these aliasing symbols that aren't defined?

[AZero13]

How does this work? Aren't these aliasing symbols that aren't defined?

An alias does not create a wrapper function. It doesn't create new assembly code that calls the old function. It is a zero-cost linker trick.

This is for the linker.

[AZero13]

Without it the compilation will fail on not UBFIX. But because this is not UBFIX and it compiles matxhing on not ubfix anyway, it shouldn't matter.

[mrgriffin]

Right, but the GetMonData3 and GetBoxMonData3 symbols did not appear to be defined on the version of the code I was commenting on because you'd unconditionally renamed them to GetMonData and GetBoxMonData.

[AZero13]

In pokemon.h, there is a macro: #define GetMonData(...) ... which automatically adds a 3 to the end of the name if 3 arguments are passed.

In pokemon.c, I define your function as: u32 GetMonData(struct Pokemon *mon, s32 field, u8 *data)

Because I passed 3 arguments, the C preprocessor instantly rewrites your function definition to be: u32 GetMonData3(struct Pokemon *mon, s32 field, u8 *data).

When agbcc compiles the file, the symbol that gets saved into the object file is GetMonData3.

[mrgriffin]

I see! That's awful.

[AZero13]

It's the best I could do. It sucks but