ICE: Out of memory error when compiling small boring code

[TyOverby]

Seen on rustc 0.12.0-pre-nightly (4d4eb1023 2014-08-02 23:36:09 +0000)

When compiling my irc message parsing library rustc uses as much CPU and memory as it can before crashing due to either an out of memory exception or an "illegal instruction" (stack overflow?).

The weird thing about this is that a single change didn't introduce the bug. As I worked on it, compile times got slower and slower until my machine could no longer even build the project.

Uninterestingly, I'm not using macros or any other rust features that might have explosive properties.

[apoelstra]

Can also reproduce on my system, Linux x86_64 with rustc d34e011b + PR 16208 + PR 15763. Halting in gdb always shows rustc sitting in Task::deschedule maybe 15 levels deep, so this is not a runaway recursion..

[TyOverby]

"Restarting" the iterator types by collecting into a Vec and then iterating from there brings the compile time down from non-terminating to 11s.

[TyOverby]

Apparently one of the types of my iterators towards the end of my program when this bug was file was

core::iter::Peekable<char,core::iter::SkipWhile<'_,char,core::iter::ByRef<'_,core::iter::SkipWhile<'_,char,core::iter::SkipWhile<'_,char,core::iter::Peekable<char,core::iter::Peekable<char,core::iter::SkipWhile<'_,char,core::iter::Peekable<char,core::iter::Peekable<char,core::str::Chars<'_>>>>>>>>>>>

Since I think all the iterator methods are #[inline(always)], this might be breaking codegen pretty hilariously.

[apoelstra]

I have been seeing similar symptoms during make check when compiling src/test/bench/shootout-fasta-redux.rs -- lots of memory usage (only 2.5-3Gb this time) and a pinned CPU in Task::deschedule.

A recent PR I was watching timed out on the Mac OSX build at the same point and was unable to merge. I'm on Linux 64, and the Linux 64 tests -did- pass, so I'd guess this is just an extreme slowdown and not a runaway loop.

Edit: The compile is quick and clean without -O; with -O I see this problem.

Edit2: No, the original bug report occurs even without optimizations, and even with old rustc's which do not have the unit test bug. (I am in the process of bisecting that one now.)

[bkoropoff]

This looks very much like issue #15244

[TyOverby]

Yeah, I'd be willing to mark this as a duplicate.

[sfackler]

Closing as duplicate of #15244