Auto-recover from corrupt Wasm builds that emit undefined env imports#4287
Auto-recover from corrupt Wasm builds that emit undefined env imports#4287Keavon wants to merge 2 commits into
env imports#4287Conversation
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Code Review
This pull request introduces automatic recovery for corrupt incremental WebAssembly builds. It adds a new sequence_then utility to run follow-up steps after a command sequence completes, and uses it to detect corrupt env imports in the generated JS glue, wiping the target directory and rebuilding if necessary. The review feedback correctly identifies a potential race condition in sequence_then where the follow_up closure (which deletes the target directory) could still execute after the sequence is killed, and suggests checking the kill flag before proceeding.
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2 issues found across 3 files
Confidence score: 2/5
- In
tools/cargo-run/src/frontend.rs, the recovery logic needs to recognize the single-quotedenvimport pattern emitted by wasm-bindgen; if it doesn’t, poisoned glue can slip past detection and the self-heal path won’t run. Add this import variant to the detector before merging so recovery is consistently triggered. - In
tools/cargo-run/src/cmd.rs,follow_upcan still run after a watcher build is cancelled unless the killed flag is checked first, which risks cleanup side effects and then skipping the recovery rebuild. Guardfollow_upbehind an early killed check before merging to avoid wiping/racing build artifacts.
Reply with feedback, questions, or to request a fix.
Re-trigger cubic
- cmd.rs: skip the follow-up when the sequence was killed, so a build the watcher superseded doesn't run the destructive heal and force the next build into an unnecessary full rebuild. - frontend.rs: also match a single-quoted `from 'env'` marker so a wasm-bindgen quote-style change can't hide poisoned glue from the detector.
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An interrupted or concurrent
cargo build --target wasm32-unknown-unknowncan leave a wasm crate's incremental codegen inconsistent, producing a.wasmwith undefined symbols that rust-lld emits asenvimports. wasm-bindgen writes these into the JS glue asimport … from "env", which Vite can't resolve, so the build succeeds but the dev server breaks, previously needing a manualcargo clean.cargo-run now checks the generated glue for the
from "env"marker after each wasm build and, when present, wipes only thewasm32-unknown-unknowntarget directory (not the shared hostdebug/buildartifacts, which other tools can hold locked on Windows) and rebuilds once. This runs on both the startup build and the watcher's rebuilds via a newsequence_then, which appends the recovery steps to the same killable sequence.Example of a poisoned scenario's terminal output after opening the localhost page in a browser: