rustc built by MIR overflows its stack for crates with very deep ASTs.

[eddyb]

These examples have been found on crater:

• boiler (failure)
• procinfo (failure)
• marksman_escape (failure)

These reproduce with stage2 but not stage1, unless stage0 is passed -Z orbit, which means a compiler built by MIR trans will use more stack space than old trans did.

For procinfo, there are just over 1000 frames, usually in the NodeIdAssigner, my guess is that its AST has a depth 500-700 in places (it's using nom, which might cause such extreme nesting).

cc @rust-lang/compiler

[nikomatsakis]

triage: P-high