fix: don't use sync fs api

[stormslowly]

Summary

close #12342

In ContextModule related plugins, filesystem sync APIs are called which is implemented by wrapping async fs API in block_on. And Rspack is running under a block_on already. This will trigger a panic

Solution

Using async api.
And sync fs Api should be forbidden later then?

Related links

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

[netlify]

✅ Deploy Preview for rspack canceled.

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🔨 Latest commit	a1a1fed
🔍 Latest deploy log	https://app.netlify.com/projects/rspack/deploys/692f13a3f564290008f99943

[Copilot]

Pull request overview

This PR converts synchronous filesystem operations to async in the context module resolution pipeline, preventing blocking operations in the tokio runtime. The changes ensure filesystem calls (metadata, read_dir) are properly awaited rather than using their synchronous variants, which aligns with the PR title's goal to "not sync fs api in tokio thread".

Key changes:

• Converted visit_dirs function to async with recursive directory traversal
• Changed ResolveContextModuleDependencies type signature from synchronous to async (returning BoxFuture)
• Updated all resolve_dependencies closures to return Box::pin(async move { ... }) for async execution

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
crates/rspack_core/src/context_module_factory.rs	Converted visit_dirs to async with #[async_recursion], changed fs calls from metadata_sync/read_dir_sync to their async equivalents, and wrapped resolve_dependencies closure in async block
crates/rspack_core/src/context_module.rs	Updated ResolveContextModuleDependencies type to return BoxFuture and added .await to resolve_dependencies call in build method
crates/rspack_plugin_module_replacement/src/context_replacement.rs	Wrapped resolve_dependencies closure in Box::pin(async move { ... }) to match new async signature, added Arc wrapping for captured HashMap

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[github-actions]

Rsdoctor Bundle Diff Analysis

Found 5 project(s) in monorepo.

📁 react-1k

Path: ../build-tools-performance/cases/react-1k/dist/rsdoctor-data.json

📌 Baseline Commit: 5dc9c8976b | PR: #12352

Metric	Current	Baseline	Change
📊 Total Size	822.6 KB	822.6 KB	0 B (0.0%)
📄 JavaScript	822.6 KB	822.6 KB	0 B (0.0%)
🎨 CSS	0 B	0 B	N/A
🌐 HTML	0 B	0 B	N/A
📁 Other Assets	0 B	0 B	N/A

📦 Download Diff Report: react-1k Bundle Diff

📁 react-5k

Path: ../build-tools-performance/cases/react-5k/dist/rsdoctor-data.json

📌 Baseline Commit: 5dc9c8976b | PR: #12352

Metric	Current	Baseline	Change
📊 Total Size	2.7 MB	2.7 MB	0 B (0.0%)
📄 JavaScript	2.7 MB	2.7 MB	0 B (0.0%)
🎨 CSS	21.0 B	21.0 B	0 B (0.0%)
🌐 HTML	0 B	0 B	N/A
📁 Other Assets	0 B	0 B	N/A

📦 Download Diff Report: react-5k Bundle Diff

📁 rome

Path: ../build-tools-performance/cases/rome/dist/rsdoctor-data.json

📌 Baseline Commit: 5dc9c8976b | PR: #12352

Metric	Current	Baseline	Change
📊 Total Size	984.3 KB	984.3 KB	0 B (0.0%)
📄 JavaScript	984.3 KB	984.3 KB	0 B (0.0%)
🎨 CSS	0 B	0 B	N/A
🌐 HTML	0 B	0 B	N/A
📁 Other Assets	0 B	0 B	N/A

📦 Download Diff Report: rome Bundle Diff

📁 react-10k

Path: ../build-tools-performance/cases/react-10k/dist/rsdoctor-data.json

📌 Baseline Commit: 5dc9c8976b | PR: #12352

Metric	Current	Baseline	Change
📊 Total Size	5.7 MB	5.7 MB	0 B (0.0%)
📄 JavaScript	5.7 MB	5.7 MB	0 B (0.0%)
🎨 CSS	21.0 B	21.0 B	0 B (0.0%)
🌐 HTML	0 B	0 B	N/A
📁 Other Assets	0 B	0 B	N/A

📦 Download Diff Report: react-10k Bundle Diff

📁 ui-components

Path: ../build-tools-performance/cases/ui-components/dist/rsdoctor-data.json

📌 Baseline Commit: 5dc9c8976b | PR: #12352

Metric	Current	Baseline	Change
📊 Total Size	2.1 MB	2.1 MB	0 B (0.0%)
📄 JavaScript	2.0 MB	2.0 MB	0 B (0.0%)
🎨 CSS	83.0 KB	83.0 KB	0 B (0.0%)
🌐 HTML	0 B	0 B	N/A
📁 Other Assets	0 B	0 B	N/A

📦 Download Diff Report: ui-components Bundle Diff

Generated by Rsdoctor GitHub Action

[github-actions]

📦 Binary Size-limit

Comparing a1a1fed to ci: remove legacy ecosystem CI yaml (#12352) by Wei

❌ Size increased by 2.50KB from 47.70MB to 47.71MB (⬆️0.01%)

[codspeed-hq]

CodSpeed Performance Report

Merging #12353 will not alter performance

_{Comparing fix/fs_sync_call_2 (a1a1fed) with main (5dc9c89)}

Summary

✅ 17 untouched