Emit dropck normalization errors in borrowck

[matthewjasper]

Borrowck generally assumes that any queries it runs for type checking will succeed, thinking that HIR typeck will have errored first if there was a problem. However as of #98641, dropck isn't run on HIR, so there's no direct guarantee that it doesn't error. While a type being well-formed might be expected to ensure that its fields are well-formed, this is not the case for types containing a type projection:

pub trait AuthUser {
    type Id;
}

pub trait AuthnBackend {
    type User: AuthUser;
}

pub struct AuthSession<Backend: AuthnBackend> {
    data: Option<<<Backend as AuthnBackend>::User as AuthUser>::Id>,
}

pub trait Authz: Sized {
    type AuthnBackend: AuthnBackend<User = Self>;
}

pub fn run_query<User: Authz>(auth: AuthSession<User::AuthnBackend>) {}
// ^ No User: AuthUser bound is required or inferred.

While improvements to trait solving might fix this in the future, for now we go for a pragmatic solution of emitting an error from borrowck (by rerunning dropck outside of a query) and making drop elaboration check if an error has been emitted previously before panicking for a failed normalization.

Closes #103899
Closes #135039

r? @compiler-errors (feel free to re-assign)

[compiler-errors]

@bors try @rust-timer queue

[bors]

⌛ Trying commit abfa754 with merge 40f1f75...

[bors]

☀️ Try build successful - checks-actions
Build commit: 40f1f75 (40f1f75bb4cd41066f6e5b10d25251675eacd0d7)

[rust-timer]

Finished benchmarking commit (40f1f75): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

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

Max RSS (memory usage)

Results (secondary -0.7%)

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)	-0.7%	[-0.7%, -0.7%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary 3.3%)

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)	3.3%	[3.3%, 3.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 778.8s -> 781.102s (0.30%)
Artifact size: 328.88 MiB -> 328.83 MiB (-0.02%)

[matthewjasper]

@craterbot run start=master end=try#40f1f75bb4cd41066f6e5b10d25251675eacd0d7 mode=check-only

[craterbot]

👌 Experiment pr-136539 created and queued.
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚧 Experiment pr-136539 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚧 Experiment pr-136539 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🎉 Experiment pr-136539 is completed!
📊 2 regressed and 8 fixed (579475 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the denylist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[bors]

☔ The latest upstream changes (presumably #137030) made this pull request unmergeable. Please resolve the merge conflicts.

[compiler-errors]

whoops, r=me after rebase

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[matthewjasper]

@bors r=compiler-errors

[bors]

📌 Commit 49cf00c has been approved by compiler-errors

It is now in the queue for this repository.

[bors]

⌛ Testing commit 49cf00c with merge ed49386...

[bors]

☀️ Test successful - checks-actions
Approved by: compiler-errors
Pushing ed49386 to master...

[rust-timer]

Finished benchmarking commit (ed49386): 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)

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

Cycles

Results (primary 4.3%)

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)	4.3%	[1.7%, 6.4%]	7
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	4.3%	[1.7%, 6.4%]	7

Binary size

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

Bootstrap: 773.598s -> 773.063s (-0.07%)
Artifact size: 360.32 MiB -> 362.34 MiB (0.56%)