-Ztrait-solver=next to -Znext-solver

[lcnr]

renames the feature flag to enable the new trait solver.

still want some feedback before merging: https://rust-lang.zulipchat.com/#narrow/stream/364551-t-types.2Ftrait-system-refactor/topic/renaming.20the.20feature.20flag.20to.20.60-Znew-solver.60.

The idea is to make it easier to add another option, e.g. to enable the solver in wfcheck or to optionally change its behavior to our new coinduction approach.

r? @compiler-errors

[compiler-errors]

This should probably still be flattened to an enum by argparsing

[compiler-errors]

Actually nvm, if we will have multiple bools then it will get unwieldy. Maybe consider a more clear name for the the "rest of the compiler" option? idk

[rustbot]

Could not assign reviewer from: compiler-errors.
User(s) compiler-errors are either the PR author, already assigned, or on vacation, and there are no other candidates.
Use r? to specify someone else to assign.

[compiler-errors]

r=me

[rustbot]

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

Some changes occurred in engine.rs, potentially modifying the public API of ObligationCtxt.

cc @lcnr, @compiler-errors

[lcnr]

@bors r=compiler-errors rollup=never

[bors]

📌 Commit ceb4f6b has been approved by compiler-errors

It is now in the queue for this repository.

[compiler-errors]

CI failure looks unrelated

[lcnr]

@bors r=compiler-errors rollup=never

[bors]

📌 Commit fa03289 has been approved by compiler-errors

It is now in the queue for this repository.

[bors]

⌛ Testing commit fa03289 with merge 2ecba0f...

[bors]

☀️ Test successful - checks-actions
Approved by: compiler-errors
Pushing 2ecba0f to master...

[rust-timer]

Finished benchmarking commit (2ecba0f): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.9%	[-1.0%, -0.9%]	4
Improvements ✅ (secondary)	-0.5%	[-0.8%, -0.3%]	21
All ❌✅ (primary)	-0.9%	[-1.0%, -0.9%]	4

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.8%	[0.8%, 0.8%]	1
Regressions ❌ (secondary)	4.5%	[4.5%, 4.5%]	1
Improvements ✅ (primary)	-1.7%	[-1.7%, -1.7%]	1
Improvements ✅ (secondary)	-2.2%	[-3.5%, -0.8%]	2
All ❌✅ (primary)	-0.4%	[-1.7%, 0.8%]	2

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.9%	[0.9%, 0.9%]	1
Regressions ❌ (secondary)	2.9%	[2.9%, 2.9%]	1
Improvements ✅ (primary)	-0.4%	[-0.4%, -0.4%]	1
Improvements ✅ (secondary)	-2.2%	[-2.3%, -2.0%]	2
All ❌✅ (primary)	0.2%	[-0.4%, 0.9%]	2

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 672.087s -> 673.223s (0.17%)
Artifact size: 312.43 MiB -> 312.46 MiB (0.01%)