Replace ParamEnv with a new type in chalk context.

[scalexm]

I left a few FIXMEs.

r? @nikomatsakis

[tmandry]

Why doesn’t the terminology line up here anymore with chalk?

[scalexm]

Mmh at some point the terminology diverged, we use Clause in rustc for ProgramClause in chalk, and ProgramClause in rustc for ProgramClauseImplication in chalk. I agree we should somehow resolve that conflict.

[nikomatsakis]

I think the meaning of these words I would like to be using:

• "clause" is one of the "base facts" we know to be true
  • in particular, this includes clauses injected via hypothesis, e.g. the clause A in A => G.
• "program clause" is something that was given in the "input program"
  • in our case, this means the stuff we created by lowering impls and so forth

In particular, program clauses are available globally at all times, whereas clauses may only be available to some goals.

[tmandry]

I love how clean this is.

[bors]

☔ The latest upstream changes (presumably #54858) made this pull request unmergeable. Please resolve the merge conflicts.

[nikomatsakis]

r=me once rebased

[rust-highfive]

The job x86_64-gnu-llvm-5.0 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

[00:12:27]    Compiling rustc_mir v0.0.0 (/checkout/src/librustc_mir)
[00:12:27]    Compiling rustc_typeck v0.0.0 (/checkout/src/librustc_typeck)
[00:12:28]    Compiling rustc_allocator v0.0.0 (/checkout/src/librustc_allocator)
[00:13:29]    Compiling rustc_traits v0.0.0 (/checkout/src/librustc_traits)
[00:13:30] error[E0491]: in type `&'set mut std::collections::HashSet<rustc::traits::Clause<'tcx>, std::hash::BuildHasherDefault<rustc_data_structures::fx::FxHasher>>`, reference has a longer lifetime than the data it references
[00:13:30]   --> librustc_traits/lowering/environment.rs:26:5
[00:13:30]    |
[00:13:30] 26 |     round: &'set mut FxHashSet<Clause<'tcx>>,
[00:13:30]    |
[00:13:30]    |
[00:13:30] note: the pointer is valid for the lifetime 'set as defined on the struct at 24:22
[00:13:30]   --> librustc_traits/lowering/environment.rs:24:22
[00:13:30]    |
[00:13:30] 24 | struct ClauseVisitor<'set, 'a, 'tcx: 'a> {
[00:13:30]    |                      ^^^^
[00:13:30] note: but the referenced data is only valid for the lifetime 'tcx as defined on the struct at 24:32
[00:13:30]   --> librustc_traits/lowering/environment.rs:24:32
[00:13:30]    |
[00:13:30] 24 | struct ClauseVisitor<'set, 'a, 'tcx: 'a> {
[00:13:30] 
[00:13:30] error: aborting due to previous error
[00:13:30] 
[00:13:30] For more information about this error, try `rustc --explain E0491`.

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[scalexm]

@bors r=nikomatsakis

[bors]

📌 Commit 0684ead65930bd8b24f0e9779e0db3d35d17760b has been approved by nikomatsakis

[bors]

☔ The latest upstream changes (presumably #55093) made this pull request unmergeable. Please resolve the merge conflicts.

[scalexm]

@bors r=nikomatsakis

[bors]

📌 Commit 55ce7a2 has been approved by nikomatsakis

[bors]

⌛ Testing commit 55ce7a2 with merge dbab381...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: nikomatsakis
Pushing dbab381 to master...