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Fix ICE with buffered lint referring to AST node deleted by everybody_loops #89500

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merged 1 commit into from
Oct 4, 2021

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FabianWolff
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Fixes #87308. Note the following comment:

// All of the buffered lints should have been emitted at this point.
// If not, that means that we somehow buffered a lint for a node id
// that was not lint-checked (perhaps it doesn't exist?). This is a bug.

As it turns out, this is not always a bug, because -Zunpretty=everybody_loops causes a lot of AST nodes to be deleted, and thus some buffered lints will refer to non-existent node ids. To fix this, my changes simply ignore buffered lints if -Zunpretty=everybody_loops is enabled, which, from my understanding, shouldn't be a big issue because it only affects pretty-printing. Of course, a more elegant solution would only ignore buffered lints that actually point at deleted node ids, but I haven't figured out an easy way of achieving this.

For the concrete example in #87308, the buffered lint is created here with the lint_node_id from here, i.e. it points at the macro expansion, which then gets deleted by ReplaceBodyWithLoop here.

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r? @petrochenkov

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@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Oct 3, 2021
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@bors r+

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bors commented Oct 4, 2021

📌 Commit a28a78f has been approved by petrochenkov

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Oct 4, 2021
Manishearth added a commit to Manishearth/rust that referenced this pull request Oct 4, 2021
…nkov

Fix ICE with buffered lint referring to AST node deleted by everybody_loops

Fixes rust-lang#87308. Note the following comment:
https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_lint/src/early.rs#L415-L417

As it turns out, this is not _always_ a bug, because `-Zunpretty=everybody_loops` causes a lot of AST nodes to be deleted, and thus some buffered lints will refer to non-existent node ids. To fix this, my changes simply ignore buffered lints if `-Zunpretty=everybody_loops` is enabled, which, from my understanding, shouldn't be a big issue because it only affects pretty-printing. Of course, a more elegant solution would only ignore buffered lints that actually point at deleted node ids, but I haven't figured out an easy way of achieving this.

For the concrete example in rust-lang#87308, the buffered lint is created [here](https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_expand/src/mbe/macro_rules.rs#L145-L151) with the `lint_node_id` from [here](https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_expand/src/mbe/macro_rules.rs#L319), i.e. it points at the macro _expansion_, which then gets deleted by `ReplaceBodyWithLoop` [here](https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_interface/src/passes.rs#L377).
Manishearth added a commit to Manishearth/rust that referenced this pull request Oct 4, 2021
…nkov

Fix ICE with buffered lint referring to AST node deleted by everybody_loops

Fixes rust-lang#87308. Note the following comment:
https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_lint/src/early.rs#L415-L417

As it turns out, this is not _always_ a bug, because `-Zunpretty=everybody_loops` causes a lot of AST nodes to be deleted, and thus some buffered lints will refer to non-existent node ids. To fix this, my changes simply ignore buffered lints if `-Zunpretty=everybody_loops` is enabled, which, from my understanding, shouldn't be a big issue because it only affects pretty-printing. Of course, a more elegant solution would only ignore buffered lints that actually point at deleted node ids, but I haven't figured out an easy way of achieving this.

For the concrete example in rust-lang#87308, the buffered lint is created [here](https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_expand/src/mbe/macro_rules.rs#L145-L151) with the `lint_node_id` from [here](https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_expand/src/mbe/macro_rules.rs#L319), i.e. it points at the macro _expansion_, which then gets deleted by `ReplaceBodyWithLoop` [here](https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_interface/src/passes.rs#L377).
bors added a commit to rust-lang-ci/rust that referenced this pull request Oct 4, 2021
…ingjubilee

Rollup of 13 pull requests

Successful merges:

 - rust-lang#83655 ([aarch64] add target feature outline-atomics)
 - rust-lang#87091 (implement advance_(back_)_by on more iterators)
 - rust-lang#88451 (Fix an ICE caused by type mismatch errors being ignored)
 - rust-lang#88452 (VecDeque: improve performance for From<[T; N]>)
 - rust-lang#89400 (Improve wording of `map_or_else` docs)
 - rust-lang#89407 (Recommend running `cargo clean` in E0514 output)
 - rust-lang#89443 (Include the length in BTree hashes)
 - rust-lang#89444 (rustdoc: use slice::contains instead of open-coding it)
 - rust-lang#89447 (Improve error message for missing angle brackets in `[_]::method`)
 - rust-lang#89453 (Consistently use 'supertrait'.)
 - rust-lang#89483 (Practice diagnostic message convention)
 - rust-lang#89500 (Fix ICE with buffered lint referring to AST node deleted by everybody_loops)
 - rust-lang#89508 (Stabilize `const_panic`)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 3d4467d into rust-lang:master Oct 4, 2021
@rustbot rustbot added this to the 1.57.0 milestone Oct 4, 2021
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ICE: hygienic-label-1.rs -Zunpretty=everybody_loops : failed to process buffered lint here (dummy = false)
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