fix(cli): NAPI_RS_FORCE_WASI only activates on 'true' or 'error' by MukundaKatta · Pull Request #3236 · napi-rs/napi-rs

MukundaKatta · 2026-04-15T07:52:28Z

Why

The generated native.js template treats process.env.NAPI_RS_FORCE_WASI as a plain truthy check. In JavaScript every non-empty string is truthy, so setting NAPI_RS_FORCE_WASI=false (intending to opt out) inadvertently triggers the WASI fallback — the same path that tries to require('./<pkg>.wasi.cjs') and fails with ENOENT for packages that don't ship a WASI binding.

Surfaced downstream in lancedb/lancedb#3267:

ENOENT: no such file or directory, open '.../@lancedb/lancedb/dist/lancedb.wasi.cjs'

The existing === 'error' branch at line 256 already shows the right pattern — this PR applies it consistently at the other four sites.

What

Extracts a single forceWasi boolean at the top of the generated script:

const forceWasi =
  process.env.NAPI_RS_FORCE_WASI === 'true' || process.env.NAPI_RS_FORCE_WASI === 'error'

and uses it at all four call sites that previously did the truthy-string check. The === 'error' branch at the bottom is preserved unchanged — it already handled its value correctly.

Behavior table

`NAPI_RS_FORCE_WASI`	Before	After
unset	native preferred; WASI only if native fails	same
`'true'`	forced WASI	forced WASI (unchanged)
`'error'`	forced WASI; throw if none	forced WASI; throw if none (unchanged)
`'false'`	forced WASI (bug)	native preferred
`'0'`	forced WASI (bug)	native preferred
anything else	forced WASI (bug)	native preferred

Scope

Template change only (cli/src/api/templates/js-binding.ts).
Downstream packages pick up the fix on their next napi build.
No existing users who set NAPI_RS_FORCE_WASI to 'true' or 'error' are affected.
No behavior change when the var is unset.

Summary by CodeRabbit

Refactor
- Improved WASI fallback loading logic to require explicit environment variable values ('true' or 'error') instead of treating any non-empty string as truthy, resulting in more predictable behavior and clearer error handling.

The generated native.js template treated process.env.NAPI_RS_FORCE_WASI as a plain truthy-string check. In JavaScript any non-empty string is truthy, including 'false' and '0', so setting NAPI_RS_FORCE_WASI=false (intending to opt out of forced WASI) inadvertently triggered the WASI fallback — the same path that tries to load <pkg>.wasi.cjs and fails with ENOENT for packages that don't ship a WASI binding. Reported by lancedb/lancedb#3267, where downstream users hit: ENOENT: no such file or directory, open '.../@lancedb/lancedb/dist/lancedb.wasi.cjs' This patch extracts a single `forceWasi` boolean at the top of the generated script (equal to 'true' or 'error') and uses it consistently at the four call sites that previously did a truthy-string check. The existing `=== 'error'` branch at the bottom is preserved unchanged — it already did the right thing. This is a template change, so the fix is picked up the next time a downstream package runs `napi build`. No behavior change for existing users who had NAPI_RS_FORCE_WASI unset or set to 'true'/'error'. Related: PR napi-rs#2919 added the 'error' tri-state; this patch completes the tri-state handling by making the other two values ('true' and everything-else) behave as documented. Signed-off-by: Mukunda Katta <[email protected]>

coderabbitai · 2026-04-15T07:52:45Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 5cd8198a-fece-4fbd-965d-a5f8d697c42b

📥 Commits

Reviewing files that changed from the base of the PR and between 0cb8eef and eb10ff2.

📒 Files selected for processing (1)

cli/src/api/templates/js-binding.ts

📝 Walkthrough

Walkthrough

The PR refines WASI-loading control flow in createCommonBinding by introducing an explicit forceWasi flag that only treats process.env.NAPI_RS_FORCE_WASI as 'true' or 'error', replacing the previous "any non-empty string is truthy" behavior. Error handling is now gated to the explicit 'error' value.

Changes

Cohort / File(s)	Summary
WASI Fallback Control Flow `cli/src/api/templates/js-binding.ts`	Introduced computed `forceWasi` flag that explicitly checks for `'true'` or `'error'` values instead of treating any non-empty string as truthy. Updated conditional logic to trigger WASI fallback on `!nativeBinding \|\| forceWasi`, and confined error-throwing behavior to explicit `'error'` value only.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

fix(cli): properly load WASM package in JS binding template #3038 — Directly modifies the same WASI-loading control flow in js-binding.ts with related environment variable and fallback condition changes.

Suggested reviewers

Brooooooklyn

Poem

🐰 A rabbit hops through env vars clear,
"True" and "error" now appear!
No guessing games with strings so vague,
The WASI fallback breaks its plague. 🌟

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main bug fix: the NAPI_RS_FORCE_WASI environment variable now only activates on explicit 'true' or 'error' values instead of treating any non-empty string as truthy.

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…e' (#3519) ## Summary Fixes the `NAPI_RS_FORCE_WASI=false` issue by upgrading `@napi-rs/cli` from `3.5.1` to `3.7.0`. Closes #3267 ## Root Cause In the `native.js` loader generated by `napi build`, the check was: ```js if (!nativeBinding || process.env.NAPI_RS_FORCE_WASI) { ``` In JavaScript, any non-empty string is truthy, so `NAPI_RS_FORCE_WASI=false` (a non-empty string) inadvertently triggered the WASI fallback path. This caused an `ENOENT` error when `lancedb.wasi.cjs` was not present. ## Fix `@napi-rs/[email protected]` ([napi-rs/napi-rs#3236](napi-rs/napi-rs#3236)) introduced a tri-state check in the template that generates `native.js`: **Before (generated by @napi-rs/[email protected]):** ```js if (!nativeBinding || process.env.NAPI_RS_FORCE_WASI) { ``` **After (generated by @napi-rs/[email protected]):** ```js const forceWasi = process.env.NAPI_RS_FORCE_WASI === 'true' || process.env.NAPI_RS_FORCE_WASI === 'error' if (!nativeBinding || forceWasi) { ``` Only the literal string `'true'` (or `'error'` for strict mode) now activates the WASI path. All other values, including `'false'`, `'0'`, or an unset variable, behave as if WASI is not forced. ## Changes - `nodejs/package.json`: bump `@napi-rs/cli` from `3.5.1` to `3.7.0` - `nodejs/package-lock.json` / `nodejs/pnpm-lock.yaml`: update lock files to match The fix is in the upstream napi-rs tool; the generated `native.js` is not committed to this repository and is produced at build time by `napi build`.

Brooooooklyn merged commit 030eb76 into napi-rs:main May 26, 2026
72 of 73 checks passed

nuthalapativarun mentioned this pull request Jun 9, 2026

fix(nodejs): treat NAPI_RS_FORCE_WASI as truthy only when set to 'true' lancedb/lancedb#3519

Merged

coderabbitai Bot mentioned this pull request Jun 11, 2026

fix(cli): emit Node 12 compatible CJS binding loader #3312

Merged

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fix(cli): NAPI_RS_FORCE_WASI only activates on 'true' or 'error'#3236

fix(cli): NAPI_RS_FORCE_WASI only activates on 'true' or 'error'#3236
Brooooooklyn merged 1 commit into
napi-rs:mainfrom
MukundaKatta:fix/napi-rs-force-wasi-truthy-string

MukundaKatta commented Apr 15, 2026 •

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MukundaKatta commented Apr 15, 2026 • edited by coderabbitai Bot Loading Uh oh! There was an error while loading. Please reload this page.

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MukundaKatta commented Apr 15, 2026 •

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