Rewatch: use a single timestamp per compile pass#8428
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cknitt
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May 17, 2026
| match dependent_module.source_type { | ||
| SourceType::SourceFile(_) => { | ||
| match (module.last_compiled_cmt, module.last_compiled_cmt) { | ||
| match (module.last_compiled_cmt, module.last_compiled_cmi) { |
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rescript
@rescript/darwin-arm64
@rescript/darwin-x64
@rescript/linux-arm64
@rescript/linux-x64
@rescript/runtime
@rescript/win32-x64
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Signed-off-by: Jaap Frolich <jfrolich@gmail.com>
jfrolich
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May 17, 2026
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Fixes #8412
Summary
Fix unnecessary recompilation/touching of downstream output files in rewatch incremental builds.
The DAG scheduler introduced by #8374 buffers completed module results and then processes them in deterministic module-name order. During that result processing, each successful module previously received fresh
last_compiled_cmi/last_compiled_cmtvalues viaSystemTime::now().That made the in-memory compile timestamps depend on result processing order rather than dependency order. If a dependency was processed after one of its dependents, the next incremental build could observe:
mark_modules_with_expired_deps_dirtyinterprets that as a stale dependent and marks it dirty. In watch mode this caused unrelated downstream modules, such as app startup/root modules, to be recompiled and their generated.mjsfiles touched. Tools like Vite then saw those touched files and performed a full reload instead of fast refresh.Fix
Use a single shared
compile_timestampfor all successful modules processed in a single compile pass.This preserves the existing behavior that successful modules are marked current after the pass, including modules that were checked but short-circuited as clean, while removing artificial ordering between modules completed in the same pass.
With a single timestamp, modules processed during the same build no longer make each other look stale on the next incremental rebuild.