Retrieve the result of drop elaboration

[sonmarcho]

[Nadrieril]

For context:

• Drop elaboration is well explained in the dev guide;
• It is run in the analysis->runtime MIR phase, the results of which are available only in mir_drops_elaborated_and_const_checked and optimized_mir;
• We can't run individual passes ourselves because they're not made public (but we could ask rustc devs for that). EDIT: see below.

[Nadrieril]

I discovered the -Z mir-enable-passes=val flag, which allows choosing exactly which mir passes to run! I'll have to experiment to see if we can get drops without other optimizations.

[sonmarcho]

I discovered the -Z mir-enable-passes=val flag, which allows choosing exactly which mir passes to run! I'll have to experiment to see if we can get drops without other optimizations.

This looks very promising!