Skip to content

fix(dev): don't panic when an HMR rebuild hits an unresolved import#10162

Merged
graphite-app[bot] merged 1 commit into
mainfrom
07-07-fix_dev_don_t_panic_when_an_hmr_rebuild_hits_an_unresolved_import
Jul 7, 2026
Merged

fix(dev): don't panic when an HMR rebuild hits an unresolved import#10162
graphite-app[bot] merged 1 commit into
mainfrom
07-07-fix_dev_don_t_panic_when_an_hmr_rebuild_hits_an_unresolved_import

Conversation

@shulaoda

@shulaoda shulaoda commented Jul 7, 2026

Copy link
Copy Markdown
Member

Description

Fixes #10136.

In a dev (FBM) session, editing a file so that one of its imports no longer resolves crashed the whole worker thread instead of reporting the error:

thread 'rolldown-worker' panicked at crates/rolldown_common/src/types/hybrid_index_vec.rs:76:28:
HybridIndexVec::Map missing idx 2 (len=1)

Root cause

When a rebuild fails with an unresolved import, trace_import_chain_from_modules enriches the error with the import chain (added in #7625). The walk follows importers edges, which cover the whole module graph. But in a partial scan, intermediate_normal_modules.modules is the sparse HybridIndexVec::Map and only holds the modules that were re-scanned. The first step from the changed module to its unchanged importer looks up an index that is not in the map, and HybridIndexVec::get panics on missing keys.

The existing error-recovery tests did not catch this because they use syntax errors. Only a DiagnosableResolveError triggers the chain tracing.

Fix

  • Add a non-panicking HybridIndexVec::try_get. The panicking get is kept as is, so real indexing bugs still surface loudly.
  • Add a non-panicking ScanStageCache::snapshot() accessor.
  • In the chain walk, read modules that are missing from the sparse table out of the last successful build's snapshot. A slot that is present but empty (the module whose scan just failed) stays skipped, so the chain output matches full builds.
  • Also stop the walk at entries recorded in the snapshot. The per-scan entry set is empty in a partial scan, so the old check never fired there.

With the fix, the rebuild reports a normal UNRESOLVED_IMPORT diagnostic with the full import chain, and the next edit recovers via a regular HMR patch.

Test

New fixture topics/hmr/error_recovery/from_rebuild_unresolved_import. Step 0 introduces an unresolvable import (this reproduced the panic before the fix), step 1 reverts it and verifies HMR recovers.

@netlify

netlify Bot commented Jul 7, 2026

Copy link
Copy Markdown

Deploy Preview for rolldown-rs canceled.

Name Link
🔨 Latest commit 3bcaebb
🔍 Latest deploy log https://app.netlify.com/projects/rolldown-rs/deploys/6a4c62da2070ca00083a1b05

@codspeed-hq

codspeed-hq Bot commented Jul 7, 2026

Copy link
Copy Markdown

Merging this PR will not alter performance

✅ 7 untouched benchmarks
⏩ 10 skipped benchmarks1


Comparing 07-07-fix_dev_don_t_panic_when_an_hmr_rebuild_hits_an_unresolved_import (13a1036) with main (f730cac)2

Open in CodSpeed

Footnotes

  1. 10 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports.

  2. No successful run was found on main (bb19a48) during the generation of this report, so f730cac was used instead as the comparison base. There might be some changes unrelated to this pull request in this report.

shulaoda commented Jul 7, 2026

Copy link
Copy Markdown
Member Author

Merge activity

  • Jul 7, 2:20 AM UTC: The merge label 'graphite: merge-when-ready' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
  • Jul 7, 2:20 AM UTC: shulaoda added this pull request to the Graphite merge queue.
  • Jul 7, 2:26 AM UTC: Merged by the Graphite merge queue.

…10162)

### Description

Fixes #10136.

In a dev (FBM) session, editing a file so that one of its imports no longer resolves crashed the whole worker thread instead of reporting the error:

```
thread 'rolldown-worker' panicked at crates/rolldown_common/src/types/hybrid_index_vec.rs:76:28:
HybridIndexVec::Map missing idx 2 (len=1)
```

#### Root cause

When a rebuild fails with an unresolved import, `trace_import_chain_from_modules` enriches the error with the import chain (added in #7625). The walk follows `importers` edges, which cover the whole module graph. But in a partial scan, `intermediate_normal_modules.modules` is the sparse `HybridIndexVec::Map` and only holds the modules that were re-scanned. The first step from the changed module to its unchanged importer looks up an index that is not in the map, and `HybridIndexVec::get` panics on missing keys.

The existing error-recovery tests did not catch this because they use syntax errors. Only a `DiagnosableResolveError` triggers the chain tracing.

#### Fix

- Add a non-panicking `HybridIndexVec::try_get`. The panicking `get` is kept as is, so real indexing bugs still surface loudly.
- Add a non-panicking `ScanStageCache::snapshot()` accessor.
- In the chain walk, read modules that are missing from the sparse table out of the last successful build's snapshot. A slot that is present but empty (the module whose scan just failed) stays skipped, so the chain output matches full builds.
- Also stop the walk at entries recorded in the snapshot. The per-scan entry set is empty in a partial scan, so the old check never fired there.

With the fix, the rebuild reports a normal `UNRESOLVED_IMPORT` diagnostic with the full import chain, and the next edit recovers via a regular HMR patch.

#### Test

New fixture `topics/hmr/error_recovery/from_rebuild_unresolved_import`. Step 0 introduces an unresolvable import (this reproduced the panic before the fix), step 1 reverts it and verifies HMR recovers.
@graphite-app
graphite-app Bot force-pushed the 07-07-fix_dev_don_t_panic_when_an_hmr_rebuild_hits_an_unresolved_import branch from 13a1036 to 3bcaebb Compare July 7, 2026 02:22
@graphite-app
graphite-app Bot merged commit 3bcaebb into main Jul 7, 2026
34 checks passed
@graphite-app
graphite-app Bot deleted the 07-07-fix_dev_don_t_panic_when_an_hmr_rebuild_hits_an_unresolved_import branch July 7, 2026 02:26
@rolldown-guard rolldown-guard Bot mentioned this pull request Jul 8, 2026
shulaoda added a commit that referenced this pull request Jul 8, 2026
## [1.1.5] - 2026-07-08

### 🚀 Features

- detect top-level import-binding reads as execution-order sensitive (#10180) by @hyf0
- sourcemap_filenames: add a sourcemapFileNames option (#9271) by @V1OL3TF0X
- binding: record plugin hook result kind in tracing spans (#10154) by @IWANABETHATGUY
- linking: skip side-effect-free modules in per-entry reachability (#10111) by @IWANABETHATGUY
- improve error message for unresolved virtual imports (#10156) by @sapphi-red
- add descriptive metadata to plugin API (#10106) by @sapphi-red
- add `--configLoader=native` option (#10118) by @sapphi-red

### 🐛 Bug Fixes

- improve invalid annotation warnings (#10185) by @hyf0
- keep deduplicated asset filenames stable once they can be observed (#10191) by @shulaoda
- sourcemap_filenames: use public option name in pattern errors (#10188) by @IWANABETHATGUY
- sourcemap_filenames: hash prepared sourcemap content (#10178) by @hyf0
- tree-shake unused circular declarators exported via export list (#10166) by @IWANABETHATGUY
- dev: don't panic when an HMR rebuild hits an unresolved import (#10162) by @shulaoda
- propagate errors from output.globals function (#9880) by @shulaoda
- dev: revert cache mutations when a partial scan fails (#10110) by @shulaoda
- dev: update importer relationships of cached modules in incremental build (#10107) by @shulaoda
- hmr: fall back to full reload when a changed module is not registered as executed (#10132) by @shulaoda
- chunk-optimizer: follow entry facade edges in runtime placement cycle check (#10101) by @hyf0
- dev: ignore watcher events after close (#10113) by @hyf0
- emit async wrapper for TLA modules under onDemandWrapping (#10086) by @IWANABETHATGUY
- gate sideEffects:false modules' side effects on body demand (#10080) by @IWANABETHATGUY
- rolldown_plugin_vite_resolve: return empty object for `browser: false` mapped modules (#10082) by @sapphi-red
- reset the word-boundary state on newline in Hires::Boundary sourcemaps (#10025) by @shulaoda
- trim an emptied chunk's outro/intro instead of skipping past it (#10029) by @shulaoda
- test each edited chunk's own start against indent exclude ranges (#10026) by @shulaoda
- preserve sourcemap mappings for indented lines when a CJS module shares the chunk (#10074) by @hyf0

### 🚜 Refactor

- separate tree-shaking side effects from execution order sensitivity (#10168) by @hyf0
- type construct_vite_preload_call to take an ObjectPattern (#10135) by @shulaoda
- treeshake: single-source the own-export classification shared with the lazy-barrel loader (#10098) by @IWANABETHATGUY
- dev: reuse Vite's bundledDev server (#10081) by @h-a-n-a
- clippy: ban std HashMap/HashSet in favour of FxHashMap/FxHashSet (#10108) by @Boshen
- treeshake: make body demand a second module bit instead of a stmt multimap (#10097) by @IWANABETHATGUY
- seal used_symbol_refs by construction after its last writer (#10091) by @hyf0
- treeshake: replace inclusion mutual recursion with a worklist engine (#10096) by @IWANABETHATGUY
- treeshake: split include_statements.rs into focused modules (#10095) by @IWANABETHATGUY
- drop redundant is_user_defined filter on partitioned entries (#10050) by @shulaoda
- project the retained export interface out of used_symbol_refs (#10089) by @hyf0
- track used external symbols separately from used_symbol_refs (#10088) by @hyf0
- make module namespace inclusion an explicit linking metadata field (#10087) by @hyf0
- rename statement evaluation metadata (#10078) by @hyf0

### 📚 Documentation

- virtual modules user-facing id convention (#10155) by @sapphi-red
- cli: clarify disabling boolean/object flags like codeSplitting (#10153) by @IWANABETHATGUY
- chore: remove Vite+ alpha banner (#10105) by @mdong1909
- write down the used_symbol_refs contract (#10090) by @hyf0
- dev/lazy: update design and implementation (#10079) by @h-a-n-a

### ⚡ Performance

- ast_scanner: stop order-sensitivity checks once a module is flagged (#10190) by @IWANABETHATGUY
- return impl ExactSizeIterator from slice-backed accessors (#10133) by @Boshen
- binding: box dev and watcher napi futures (#10103) by @Boshen

### 🧪 Testing

- move string_wizard replace unit tests to the JS magic-string suite (#10176) by @IWANABETHATGUY
- dev: assert incremental scan state matches a fresh full build after each HMR step (#10115) by @shulaoda
- dev: restore runtime assertions of delete_file_not_used_anymore (#10112) by @shulaoda
- dev: fix flaky dev server tests in CI (#10152) by @h-a-n-a
- add regression test for #10099 (lazyBarrel drops default-import binding but keeps its property reads) (#10109) by @IWANABETHATGUY

### ⚙️ Miscellaneous Tasks

- deploy website to Void via GitHub OIDC (#10192) by @Boshen
- deps: update oxc to 0.139.0 (#10161) by @shulaoda
- deps: update test262 submodule for tests (#10160) by @rolldown-guard[bot]
- rolldown_plugin_utils: remove dead asset-url and css scaffolding (#10131) by @shulaoda
- deps: revert vite-plus to v0.2.1 (#10148) by @shulaoda
- deps: update github actions (#10141) by @renovate[bot]
- deps: update dependency rust to v1.96.1 (#10145) by @renovate[bot]
- deps: update npm packages (#10142) by @renovate[bot]
- deps: update rust crates (#10143) by @renovate[bot]
- deps: update napi to v3.10.3 (#10121) by @renovate[bot]
- rolldown_utils: remove unused time module (#10138) by @shulaoda
- remove dead CopyModulePlugin::is_active method (#10129) by @shulaoda
- remove dead LazyCompilationContext::is_lazy_module method (#10128) by @shulaoda
- remove dead BuildDiagnostic::downcast_ref method (#10127) by @shulaoda
- deps: update dependency vite-plus to v0.2.2 (#10084) by @renovate[bot]
- deps: update rust crate oxc_sourcemap to v8.1.0 (#10122) by @renovate[bot]
- deps: update crate-ci/typos action to v1.48.0 (#10124) by @renovate[bot]
- enable more clippy restriction lints (#10114) by @Boshen
- deps: update rust dependencies (#10100) by @Boshen
- deps: update oxc resolver to v11.23.0 (#10083) by @renovate[bot]

### ◀️ Revert

- Revert "chore(deps): revert vite-plus to v0.2.1" (#10157) by @h-a-n-a
- "fix(hmr): fall back to full reload when a changed module is not registered as executed (#10132)" (#10151) by @shulaoda

### ❤️ New Contributors

* @V1OL3TF0X made their first contribution in [#9271](#9271)

Co-authored-by: shulaoda <[email protected]>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

[Panic]: thread 'rolldown-worker' (11046093) panicked at crates/rolldown_common/src/types/hybrid_index_vec.rs:76:28

2 participants