rustc: Uses 75G of RAM and takes 1h30 on attached

[penguin42]

The code at http://www.treblig.org/daveG/play-75G.rs (attached) causes rustc to take 75G of RAM and 1.5hours to compile (before it spits a reasonable error)

It is an experiment with type unification and does contain a screwup; when I fixed the screwup it returned to taking about 2mins and about 250MB even with all my type unification fun; I've not changed the recursion limits.

75G is probably bad; I can't necessarily call it a bug but it does smell suspicious; I'm wondering if it's associated with the code that reports the 'trait bound .... is not satisfied' and providing the explanation of it.
play-75G.txt

rustc 1.17.0
binary: rustc
commit-hash: unknown
commit-date: unknown
host: x86_64-unknown-linux-gnu
release: 1.17.0
LLVM version: 3.9

[kennytm]

Could you run with newer rustc (1.18-stable, 1.19-beta or nightly) and see if it still takes more than 2 minutes?

Also, you could use rustc -Ztime-passes play-75G.rs to see at which step the compiler is stuck.

[jonas-schievink]

Happens on current nightly (but I aborted after a few minutes at >2GiB), it gets stuck after variance testing, so it's inside "wf checking" when the problem occurs.

[jonas-schievink]

Triage: Still uses way too much RAM, still inside wf checking

[Mark-Simulacrum]

This now hits the first error in ~2.5 minutes for me using somewhere around ~20-30 GB of RAM (didn't watch top too closely) at peak. It does continue to run afterwards, using increasingly more memory, but it seems like the first error is the most important part...

[tivrfoa]

The code at http://www.treblig.org/daveG/play-75G.rs (attached) causes rustc to take 75G of RAM and 1.5hours to compile (before it spits a reasonable error)

It is an experiment with type unification and does contain a screwup; when I fixed the screwup it returned to taking about 2mins and about 250MB even with all my type unification fun; I've not changed the recursion limits.

75G is probably bad; I can't necessarily call it a bug but it does smell suspicious; I'm wondering if it's associated with the code that reports the 'trait bound .... is not satisfied' and providing the explanation of it. play-75G.txt

rustc 1.17.0 binary: rustc commit-hash: unknown commit-date: unknown host: x86_64-unknown-linux-gnu release: 1.17.0 LLVM version: 3.9

It seems the link is not available anymore: http://www.treblig.org/daveG/play-75G.rs

@penguin42 , could you share the code here, please?

[penguin42]

I've put the file back at that link again; and checked it's still taking over an hour and somewhere over 20G and still going.

[penguin42]

Ah there we go, it doesn't like a .rs file, so this is .rs.txt
play-75G.rs.txt