feat(linter/plugins): implement code path analysis (CFG)

[overlookmotel]

Implement CFG (or "code path analysis" as ESLint calls it).

This is the was the last remaining gap in our API.

The implementation is pretty slow, I imagine. I've pulled in ESLint's code for the actual control flow graph construction, and copied ESLint's code for the rest.

Fitting with how we combine enter and exit nodes for leaf nodes (Identifiers etc) required skipping creating "steps" for exiting leaf nodes, which should also be a perf gain, as they're so common. But that apart, I've made no effort to optimize it. There's plenty of scope for improving it. I've added comments with some starting points for doing that, and will open an issue in the hope someone would like to pick up on that.

I also cannot for the life of me figure out how to add the CFG event handlers (onCodePathStart etc) to VisitorObject type, without breaking everything. Me and Claude went at it for about an hour, and got nowhere. So I'm just leaving that for now.

[overlookmotel]

• fix(linter/plugins): include hashbang in comments #17231
• fix(ast_tools): visit nested objects to add __proto__: NodeProto in raw transfer codegen #17230
• feat(linter/plugins): implement code path analysis (CFG) #17229 👈 (View in Graphite)
• main

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[Copilot]

Pull request overview

This PR implements Control Flow Graph (CFG) analysis, also known as "Code Path Analysis" in ESLint terminology, which was the last remaining gap in the plugin API. The implementation integrates ESLint's code path analysis functionality to support CFG event handlers like onCodePathStart, onCodePathEnd, etc., enabling plugin rules that depend on control flow information.

Key changes:

• Added CFG event handlers support to the visitor system
• Implemented CFG construction using ESLint's CodePathAnalyzer
• Extended type ID mappings to include CFG event names
• Added comprehensive test fixtures to verify CFG functionality and error handling

Reviewed changes

Copilot reviewed 19 out of 22 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
apps/oxlint/src-js/plugins/cfg.ts	New module implementing CFG construction and AST walking with CFG events
apps/oxlint/src-js/plugins/visitor.ts	Extended visitor compilation to support CFG event handlers with new VISITOR_CFG state
apps/oxlint/src-js/plugins/lint.ts	Integrated CFG walking when visitor contains CFG event listeners
apps/oxlint/src-js/plugins/selector.ts	Added filtering to exclude CFG event names from node type selectors
apps/oxlint/src-js/generated/type_ids.ts	Added CFG event names to type ID mappings
tasks/ast_tools/src/generators/estree_visit.rs	Modified codegen to include CFG event names in type ID map
apps/oxlint/test/fixtures/cfg/*	Added test fixtures to verify CFG event handling
apps/oxlint/test/fixtures/lint_visit_cfg_error/*	Added test fixtures to verify error handling and state reset
apps/oxlint/conformance/src/filter.ts	Removed CFG-dependent rules from exclusion list
pnpm-lock.yaml, apps/oxlint/package.json	Added @eslint/plugin-kit dependency for CFG types

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

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Merge activity

• Dec 21, 8:53 PM UTC: overlookmotel added this pull request to the Graphite merge queue.
• Dec 21, 9:00 PM UTC: Merged by the Graphite merge queue.