[hir-ty] Missed RPIT in ide/src/rename.rs

[snprajwal]

I've written a tool that walks the AST and resolves all exprs, collecting the types. I've tested this on other big projects in debug mode (notably rustfmt) and it works fine. Running it on rust-analyzer itself causes it to panic on line 206 in ide/src/rename.rs with Missed RPIT in `insert_inference_vars_for_rpit` .

rust-analyzer/crates/ide/src/rename.rs

Lines 204 to 208 in dd2354c

	syntax: &SyntaxNode,
	FilePosition { file_id, offset }: FilePosition,
	) -> RenameResult<impl Iterator<Item = (FileRange, SyntaxKind, Definition)>> {
	let token = syntax.token_at_offset(offset).find(|t| matches!(t.kind(), SyntaxKind::STRING));

The error is coming from here:

rust-analyzer/crates/hir-ty/src/infer.rs

Lines 980 to 982 in dd2354c

	if let Entry::Vacant(e) = self.result.type_of_rpit.entry(id) {
	never!("Missed RPIT in `insert_inference_vars_for_rpit`");
	e.insert(TyKind::Error.intern(Interner));

Not sure how to reproduce this with a test or code action. No issues in release mode since never! doesn't show up without debug assertions.

[ShoyuVanilla]

Could you tell me what project causes that panic? Or I think that you could reproduce it by running rust-analyzer analysis-stats in that project.

[lnicola]

Sounds like it's panicking on r-a itself, but yeah, we want analysis-stats to catch it.

[ShoyuVanilla]

Sounds like it's panicking on r-a itself, but yeah, we want analysis-stats to catch it.

Ah, it sounds like that indeed 😅

[snprajwal]

$ rust-analyzer analysis-stats --parallel --only ide::rename::find_definitions crates/ide/
Database loaded:     1.60s, 525minstr, 98mb (metadata 604.73ms, 5405kinstr, 1047kb; build 365.18ms, 11minstr, 45kb)
  item trees: 1288
Item Tree Collection: 800.94ms, 6805minstr, 128mb
  crates: 58, mods: 1139, decls: 29656, bodies: 28777, adts: 2049, consts: 1718
Item Collection:     15.26s, 75ginstr, 1474mb
Body lowering:       351.25ms, 2640minstr, 80mb
Parallel Inference:  36.42s, 101kinstr, 1816mb
  exprs: 351, ??ty: 0 (0%), ?ty: 0 (0%), !ty: 0
  pats: 87, ??ty: 0 (0%), ?ty: 0 (0%), !ty: 0
Inference:           39.62ms, 245minstr, 2768b
MIR lowering:        21.27s, 97ginstr, 451mb
Mir failed bodies: 45 (0%)
Data layouts:        86.04ms, 352minstr, 19mb
Failed data layouts: 0 (0%)
Const evaluation:    51.86ms, 219minstr, 4mb
Failed const evals: 3 (0%)
Total:               74.40s, 183ginstr, 3974mb

[ShoyuVanilla]

$ rust-analyzer analysis-stats --parallel --only ide::rename::find_definitions crates/ide/
Database loaded:     1.60s, 525minstr, 98mb (metadata 604.73ms, 5405kinstr, 1047kb; build 365.18ms, 11minstr, 45kb)
  item trees: 1288
Item Tree Collection: 800.94ms, 6805minstr, 128mb
  crates: 58, mods: 1139, decls: 29656, bodies: 28777, adts: 2049, consts: 1718
Item Collection:     15.26s, 75ginstr, 1474mb
Body lowering:       351.25ms, 2640minstr, 80mb
Parallel Inference:  36.42s, 101kinstr, 1816mb
  exprs: 351, ??ty: 0 (0%), ?ty: 0 (0%), !ty: 0
  pats: 87, ??ty: 0 (0%), ?ty: 0 (0%), !ty: 0
Inference:           39.62ms, 245minstr, 2768b
MIR lowering:        21.27s, 97ginstr, 451mb
Mir failed bodies: 45 (0%)
Data layouts:        86.04ms, 352minstr, 19mb
Failed data layouts: 0 (0%)
Const evaluation:    51.86ms, 219minstr, 4mb
Failed const evals: 3 (0%)
Total:               74.40s, 183ginstr, 3974mb

Did that module panicked? The log shows nothing abnormal 🤔

[snprajwal]

So far, with a release build, there is no sign of failure. I'm trying to reproduce it with a local debug build of rust-analyzer. I'll let you know once I'm able to isolate the panic. If this doesn't work, I'll put up a proof-of-concept project where I can reproduce the exact problem.

[ShoyuVanilla]

I'll try it with a debug build, too

[snprajwal]

Here's you go: https://github.com/snprajwal/ra-rpit-failure

Just change the path variable in main.rs to point to the local repo, cargo run triggers the panic.

There is also the chance that I'm doing something incorrectly during the setup - if you do figure that out, please let me know :)