Mir: Trans Constant Operands

[nikomatsakis]

Translating constant operands in MIR is only partially implemented. We don't support it in all modes, and there are various kinds of constants that are unimplemented. See librustc_trans/trans/mir/operand.rs and librustc_trans/trans/mir/constant.rs

[nagisa]

It seems like there’s only ConstVal::Function in librustc_trans/trans/consts.rs left. Everything else seems to be implemented.

The problem is that, AFAIR, @oli-obk moved trans_constval from mir-specific code to trans::consts, but to translate ConstVal::Function you need code from trans::mir::did. So either we move trans_constval back into MIR-specific trans code, or attempt to find a place outside MIR-code for functions in mir::did.

[oli-obk]

it should be trivial to move back. I think it was only important to move it into its own function, it can reside in trans::mir without any troubles