Duplicate ~const bounds with a non-const one in effects desugaring

[fee1-dead]

This should unblock #116058.

r? @oli-obk

[compiler-errors]

So every ~const Foo bound gets desugared as Foo<host> + Foo<false>? If not, please leave a more detailed description of what this desugaring does and how it affects things like projection bounds.

[oli-obk]

This lgtm, but I'd like an explanation somewhere why we aren't just elaborating the trait bound in

rust/compiler/rustc_infer/src/traits/util.rs

Line 254 in 4fec845

ty::PredicateKind::Clause(ty::ClauseKind::Trait(data)) => {

(where we add super trait bounds). I'm sure when I tried that there were all kinds of problems with it, but maybe your design could work?

[fee1-dead]

(where we add super trait bounds). I'm sure when I tried that there were all kinds of problems with it, but maybe your design could work?

When I tried that, multiple tests fail, including project.rs, which is what this PR intends to fix

[oli-obk]

@bors r+

[bors]

📌 Commit f0f89d6 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit f0f89d6 with merge 616e379...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing 616e379 to master...

[rust-timer]

Finished benchmarking commit (616e379): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.0%	[-2.0%, -2.0%]	1
All ❌✅ (primary)	-	-	0

Cycles

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

Binary size

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

Bootstrap: 626.67s -> 626.338s (-0.05%)
Artifact size: 305.60 MiB -> 305.62 MiB (0.01%)