Intern provided namespaces to fix parallel-compilation resolution race#20021
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T-Gro wants to merge 2 commits into
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Intern provided namespaces to fix parallel-compilation resolution race#20021T-Gro wants to merge 2 commits into
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Follow-up to dotnet#19969, which interned provided *type* entities behind a lock-free CAS append + entitiesVersion design. The namespace entities on a provided type's path never got the same treatment: AddModuleOrNamespaceByMutation appended non-atomically (losing updates that race AddProvidedTypeEntity's CAS append) and the two namespace-materialization sites deduped with a non-atomic check-then-act, so two threads could each build a disjoint namespace subtree and strand the provided types interned under the orphan (spurious FS0001/FS0039). Make the namespace append atomic (shared AppendEntityByMutation CAS loop) and add GetOrInternNamespaceEntity, reusing the single providedEntitiesByMangledName intern table (one mangled name -> one entity per parent). Its factory reuses any pre-existing module/namespace of that name before creating, so a provider extending a real namespace no longer forks a duplicate. Both injection sites route through it. modulesByDemangledNameCache is now version-stamped since namespace appends can run concurrently with ModulesAndNamespacesByDemangledName reads. Fixes dotnet#20020 Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
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…o sites The provided-entity interning added for dotnet#20020 hand-rolled the ConcurrentDictionary<_, Lazy<_>> + GetOrAdd(key, fun _ -> lazy f).Value compute-once idiom that already recurs in StableNiceNameGenerator, AnonTypeGenerationTable and the FSI xmlDoc cache. Factor it into a single GetOrAddLazy extension in illib and route all four sites through it. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
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Fixes #20020
Under graph-based (parallel) type checking, the namespace entities on a
provided type's path were appended non-atomically and deduplicated with a
racy check-then-act, so concurrent linking from multiple files could build
disjoint namespace subtrees and strand provided types (spurious FS0001 /
FS0039). Namespace entities are now interned and appended with the same
lock-free CAS design already used for provided-type entities.
The compute-once
ConcurrentDictionary<_, Lazy<_>>idiom the interningrelies on is factored into a shared
GetOrAddLazyhelper and reused by theexisting name-generation and codegen caches.