Filter lifetimes from impl trait parent generics

[cramertj]

Also temporarily breaks late-bound lifetimes, since @eddyb wasn't sure what I should do about those.

[rust-highfive]

r? @pnkfelix

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[cramertj]

r? @nikomatsakis

@pnkfelix is out, I think.

[arielb1]

cc me

[cramertj]

cc @eddyb

[cramertj]

Tests are now passing locally.

[kennytm]

Failed to build librustc_data_structures at stage1.

[00:18:48]    Compiling rustc_data_structures v0.0.0 (file:///checkout/src/librustc_data_structures)
[00:18:49] error: internal compiler error: /checkout/src/librustc/ty/subst.rs:411: Region parameter out of range when substituting in region 'a (root type=None) (index=2)
[00:18:49] 
[00:18:49] note: the compiler unexpectedly panicked. this is a bug.
[00:18:49] 
[00:18:49] note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
[00:18:49] 
[00:18:49] note: rustc 1.21.0-dev (d09f53bc8 2017-08-12) running on x86_64-unknown-linux-gnu
[00:18:49] 
[00:18:49] thread 'rustc' panicked at 'Box<Any>', /checkout/src/librustc_errors/lib.rs:434:8
[00:18:49] note: Run with `RUST_BACKTRACE=1` for a backtrace.
[00:18:49] 
[00:18:49] error: Could not compile `rustc_data_structures`.

[cramertj]

Well that's certainly weird... I wonder how I got it to work locally.

[bors]

☔ The latest upstream changes (presumably #43710) made this pull request unmergeable. Please resolve the merge conflicts.

[aidanhs]

Hi @cramertj, just a friendly ping to make sure this is still on your radar! I can see there are some merge conflicts.

[arielb1]

🕸 This PR had been inactive for 2 weeks. Closing it to keep our queue clean. Feel free to reopen. 🕸