[v3, windows] Fix generate bindings failing with "Access is denied" when Vite dev server is running by leaanthony · Pull Request #5561 · wailsapp/wails

leaanthony · 2026-06-10T10:18:44Z

Description

Fixes #5515 — a regression introduced in v3.0.0-alpha.96 by #5367.

The atomic directory swap from #5367 (os.RemoveAll + os.Rename) fails on Windows when a file watcher such as Vite's dev server is running: the watcher holds an open handle on the watched bindings directory (via ReadDirectoryChangesW), so deleting it leaves the name in delete-pending state and the subsequent rename over it is rejected with Access is denied.

The fix

Bindings are still generated into a dot-prefixed sibling temp directory (invisible to chokidar during generation, as before), but the result is now installed by syncing files into the output directory instead of replacing the directory itself:

The output directory is never deleted or renamed, so Windows watcher handles are never violated — fixes [V3, Windows] generate bindings fails with "Access is denied" on Windows when Vite dev server is running (v3.0.0-alpha.96) #5515.
The directory delete+recreate cascade that caused the chokidar rename-event loop (the memory leak fixed by fix: atomic directory swap for bindings generation prevents chokidar rename loop (#3976) #5367 / Node process on Windows 11 consumes memory continuously, increasing about 3mb a second without being released #3976) still never happens, so that fix is preserved.
Unchanged files are left untouched (content-compared before replacing), so the dev server only reloads files that actually changed — strictly fewer HMR events than the directory swap, which invalidated everything.
File operations retry briefly with exponential backoff on Windows to ride out transient locks from watchers and antivirus scanners.

If the output directory doesn't exist at all, the whole tree is still moved with a single rename (fast path).

Type of change

Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

New unit tests for syncDirs covering: no pre-existing destination, update+stale-delete with unchanged files verified untouched (mtime preserved), file↔directory type mismatches, and fully identical content.
End-to-end on macOS: built wails3 and ran generate bindings -clean against v3/examples/binding twice — second run over existing output with planted stale files/dirs. Stale entries were removed, unchanged files kept their original mtimes (i.e. were not rewritten), and no temp directories were left behind.
go test ./internal/commands/ passes; go vet clean.

The Windows-with-Vite-running scenario from the issue would be good to confirm on a Windows machine, but the failing operation (rename over a watched directory) is structurally eliminated rather than retried around.

Checklist:

My code follows the general coding style of this project
I have added tests that prove my fix is effective or that my feature works
I have updated v3/UNRELEASED_CHANGELOG.md

Summary by CodeRabbit

Bug Fixes
- wails3 generate bindings no longer fails on Windows with "Access is denied" when the Vite dev server is running; bindings are now synced into the output to avoid watcher/rename issues and improve reliability.
Tests
- Added comprehensive cross-platform tests for bindings synchronization to ensure correct updates, deletions, type reconciliation, and idempotence.

…e output directory (#5515) The atomic directory swap introduced in #5367 (RemoveAll+Rename) fails on Windows with "Access is denied" when a file watcher such as Vite's dev server is running: the watcher holds an open handle on the watched bindings directory, so deleting it leaves the name in delete-pending state and the subsequent rename over it is rejected. Keep generating into the dot-prefixed temp directory (still invisible to chokidar during generation), but install the result by syncing files into the output directory instead of replacing the directory itself: - the output directory is never deleted or renamed, so Windows watcher handles are never violated (#5515) - the directory delete+recreate cascade that caused the chokidar rename-event loop still never happens (#3976) - unchanged files are left untouched, so the dev server only reloads files that actually changed File operations retry briefly with backoff on Windows to ride out transient locks from watchers and antivirus scanners. Fixes #5515

coderabbitai · 2026-06-10T10:19:01Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Run ID: 563fb06d-233c-4982-8ada-0eb6b2905d57

📥 Commits

Reviewing files that changed from the base of the PR and between 4f38b0a and 3a30f00.

📒 Files selected for processing (3)

v3/internal/commands/bindings.go
v3/internal/commands/bindings_sync.go
v3/internal/commands/bindings_sync_test.go

🚧 Files skipped from review as they are similar to previous changes (3)

v3/internal/commands/bindings.go
v3/internal/commands/bindings_sync_test.go
v3/internal/commands/bindings_sync.go

Walkthrough

This PR replaces the atomic directory swap (rename) in bindings generation with a file-by-file synchronization approach (syncDirs), adds Windows-aware retry/backoff, integrates it into GenerateBindings, adds tests, and records a changelog entry for the Windows fix.

Changes

Bindings sync implementation and integration

Layer / File(s)	Summary
File synchronization utility with retry logic `v3/internal/commands/bindings_sync.go`	`syncDirs(src, dst)` mirrors source into destination by fast-path rename when dst is absent, or by walking src to copy/replace differing entries, skipping identical regular files, resolving type mismatches, removing stale dst entries, and finally deleting src. Helpers: `replaceFile`, `sameFileContent`, and `withRetry` (Windows-only exponential backoff).
Synchronization test suite `v3/internal/commands/bindings_sync_test.go`	Test helpers `writeFiles`, `readTree`, `checkTree` and five test cases verifying: destination creation, updates+deletes+mtime preservation, file-vs-directory type mismatch reconciliation, handling destination-as-file, and identical-content no-op.
Bindings generation integration `v3/internal/commands/bindings.go`	`GenerateBindings` now generates into a dot-prefixed temp sibling and calls `syncDirs(generationDir, absPath)` instead of `RemoveAll+Rename`; also changes mkdir mode to `0o755` and updates error messaging to mention possible partial updates.
Changelog entry `v3/UNRELEASED_CHANGELOG.md`	Adds a Fixed entry describing that `wails3 generate bindings` no longer fails with "Access is denied" on Windows when Vite dev server is running (syncs generated files instead of renaming).

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related issues

[V3, Windows] generate bindings fails with "Access is denied" on Windows when Vite dev server is running (v3.0.0-alpha.96) #5515: Addresses the Windows "Access is denied" rename failure during bindings generation when Vite dev server is running.

Possibly related PRs

wailsapp/wails#5367: Related work that also writes to a dot-prefixed temp directory to avoid chokidar/Vite rename loops; this PR further replaces the final swap with file-by-file sync.

Suggested labels

size:XL, lgtm

Suggested reviewers

fbbdev

Poem

🐰 I hopped through code to mend the bind,
Swapped renames for syncs, a gentler kind.
No more "Denied!" from Windows' gate,
Vite can watch—no furious state.
Hooray, small files dance into place.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main fix: preventing generate bindings from failing with 'Access is denied' on Windows when Vite dev server is running.
Description check	✅ Passed	The description provides comprehensive context including issue reference, root cause, solution approach, testing details, and completed checklist items, addressing all key template sections.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

Create stacked PR
Commit on current branch

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch fix/5515-bindings-rename-windows

Warning

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🔧 golangci-lint (2.12.2)

level=error msg="[linters_context] typechecking error: pattern ./...: directory prefix . does not contain main module or its selected dependencies"

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Copilot

Pull request overview

This PR fixes a Windows-specific regression where wails3 generate bindings fails with “Access is denied” when the bindings directory is being watched (e.g. by Vite/chokidar). It replaces the previous “atomic directory swap” install step with a per-file sync into the existing output directory to avoid deleting/renaming a watched directory.

Changes:

Install generated bindings by syncing files into the existing output directory (instead of RemoveAll + Rename over the directory) to avoid Windows watcher handle conflicts.
Add syncDirs utility with Windows retry/backoff for transient file locks.
Add unit tests covering update/delete behavior, type mismatches, and “identical content leaves mtimes untouched”.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
v3/UNRELEASED_CHANGELOG.md	Adds a changelog entry for the Windows “Access is denied” bindings fix.
v3/internal/commands/bindings.go	Switches bindings installation step from directory swap to `syncDirs(...)`.
v3/internal/commands/bindings_sync.go	Implements directory syncing logic + Windows retry/backoff helper.
v3/internal/commands/bindings_sync_test.go	Adds unit tests for the sync behavior and mtime preservation for unchanged files.

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- Handle the output path existing as a regular file: clear it and move the generated tree into place (with test) - Fall back to remove+rename in replaceFile for destinations that os.Rename cannot replace on Windows (read-only attribute) - Retry the final temp directory removal like other file operations - Use 0o755 for created directories, consistent with the rest of the package

Bundles content from the failed alpha.99 release (tag pushed but no GitHub release created due to token misconfiguration) together with the alpha.100 cycle. Includes: - MacWebviewPreferences WKWebView extensions (#5549) - generate bindings "Access is denied" fix on Windows (#5561) - Linux frameless JS resize / scrollbar edge detection fix (#5368) - Windows updater cross-volume rename fallback (#5560)

Copilot AI review requested due to automatic review settings June 10, 2026 10:18

Copilot started reviewing on behalf of leaanthony June 10, 2026 10:18 View session

fix(v3): don't sleep after the final retry attempt in withRetry

4f38b0a

Copilot AI reviewed Jun 10, 2026

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Comment thread v3/internal/commands/bindings_sync.go

Comment thread v3/internal/commands/bindings_sync.go

Comment thread v3/internal/commands/bindings_sync.go Outdated

Comment thread v3/internal/commands/bindings_sync.go Outdated

leaanthony merged commit aceac48 into master Jun 10, 2026
119 checks passed

leaanthony deleted the fix/5515-bindings-rename-windows branch June 10, 2026 11:06

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[v3, windows] Fix generate bindings failing with "Access is denied" when Vite dev server is running#5561

[v3, windows] Fix generate bindings failing with "Access is denied" when Vite dev server is running#5561
leaanthony merged 3 commits into
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leaanthony commented Jun 10, 2026 •

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