Amiga C compilers are still in the stone age unfortunately.
What we need is one C/C++/asm compiler suite for all Amiga camps.
Select which Amiga API one wants to develop for (or compatible API) and the IDE should highlight incompatible API and offer to rewrite source code.
Help system linked to an online API comparison site, showing more details and example usage for different Amiga flavours.
Maybe offending APIs could be wrapped into a compatible function / class.
The same would be required for GFX/sound RTG APIs.