My favorite toolchain would be a m68k-atari-tos cross-compiler, with ELF object file format, traditional TOS executable format with DRI symbols, short ints by default, alignment on 2 bytes boundaries, 68000 only, no FPU, and no MiNT support.If this would be the case (i.e. one "primitive" library for plain TOS apps and one "advanced" library for ported stuff)... hell, why not? ;-) But yes, topis is about MPFR ;-)
Since it is out-of-topic, let's stop here ;-)