Track override chain assemblies in symbol-based mode#143
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In the symbol-based analysis path, member access via an `override` only credited the override's containing assembly. The C# compiler validates the entire override chain at compile time, so any assembly that declares an overridden base member must remain a reference -- removing it produces CS0012 errors. Symbol-based RT, on `IPropertyReferenceOperation` / `IInvocationOperation` / `IEventReferenceOperation`, walked only `Member.ContainingAssembly` (= override's assembly) and never visited `Member.OverriddenProperty?.ContainingAssembly` (= base's assembly), so the consumer's reference to the base assembly was wrongly flagged RT0002 removable. Fix: add a `TrackOverriddenChain` helper that walks `OverriddenMethod` / `OverriddenProperty` / `OverriddenEvent` chains and tracks every containing assembly. Call it from the `IInvocationOperation` and `IMemberReferenceOperation` branches. Fields don't have override chains. Adds five regression tests that all fail without this change: - `UsedViaOverridePropertyAccess`: the canonical scenario - `UsedViaOverrideMethodCall`: method variant - `UsedViaOverrideEventAccess`: event variant - `UsedViaOverrideMultiLevelChain`: three-level A -> B -> C chain - `UnrelatedReferenceNotMarkedByOverride`: negative test ensuring the fix doesn't over-credit unrelated assemblies Different code path from #141 (qualifier tracking on inherited static member access) and #142 (delegate parameter / return types). Surfaced by a QuickBuild trial of the symbol-based mode. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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…145) In the symbol-based analysis path, only the immediate base type's containing assembly was credited via `TrackType(namedType.BaseType)`. The C# compiler validates the entire base-type chain plus implemented interfaces at type-check time -- CS0012 fires when *any* link's defining assembly is missing -- so any assembly along the chain must remain a reference. With `<DisableTransitiveProjectReferences>true</...>`, the chain doesn't flow transitively, so the consumer must explicitly reference grandparent assemblies. Symbol-based RT, when handling `INamedTypeSymbol`, walked only the immediate `BaseType` and direct `Interfaces`, never recursing further up. So for `Consumer : Provider` where `Provider : ProviderDependency` in another assembly, the consumer's reference to `ProviderDependency` was wrongly flagged RT0002 removable. Fix: extend `TrackType`'s `INamedTypeSymbol` branch to walk the full `BaseType` chain and `AllInterfaces` collection. `AllInterfaces` is broader than `Interfaces` (includes transitively-implemented interfaces) and mirrors what the compiler validates. A `ConcurrentDictionary<ISymbol, byte>` keyed via `SymbolEqualityComparer.Default` gates the chain walk to break self-referential cycles such as `int -> AllInterfaces[IComparable<int>] -> typeArg int -> ...` and to avoid redundant work. Adds seven regression tests that all fail without this change: - `UsedViaInheritedBaseType`: the canonical issue #144 scenario - `UsedViaImplementedInterface`: interface in the chain - `UsedViaMultiLevelInheritanceChain`: three-level A <- B <- C - `UsedViaInheritanceChainOnVariableType`: chain via parameter type - `UsedViaMixedBaseAndInterfaceChain`: base + interface, four asms - `UsedViaGenericConstraintBaseChain`: `where T : Provider` constraint - `UnrelatedReferenceNotMarkedByInheritance`: negative test ensuring the fix doesn't over-credit unrelated assemblies Verified against upstream repro https://github.com/olstakh/RT_Gap_Inheritance: `Consumer` builds with 0 RT warnings (was emitting RT0002 with v3.5.2). Different code path from #141 (qualifier tracking on inherited static member access), #142 (delegate parameter / return types), and #143 (override chains). Same family of "symbol traversal misses a chain" gaps; same reporter (olstakh). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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In the symbol-based analysis path (
ReferenceTrimmerUseSymbolAnalysis=true), member access via anoverrideonly credited the override's containing assembly. The C# compiler validates the entire override chain at compile time, so any assembly that declares an overridden base member must remain a reference -- removing it producesCS0012errors.The bug
csharp // Assembly A public abstract class Base { public abstract string SomeProperty { get; } } // Assembly B (refs A) public class Derived : Base { public override string SomeProperty => ""value""; } // Assembly C (refs B and A) var s = new Derived().SomeProperty; // C# compiler validates the full override chainSymbol-based RT, on
IPropertyReferenceOperation/IInvocationOperation/IEventReferenceOperation, walked onlyMember.ContainingAssembly(= override's assembly = B) and never visitedMember.OverriddenProperty?.ContainingAssembly(= A). So C's reference to A was wrongly flaggedRT0002removable.Surfaced by a QuickBuild trial:
QAnalysisLibTestsaccessesGuardianArtifactPublisher.AdoContainerName, which overrides an abstract member declared onAdoArtifactUtilsinVstsTaskApiClient. The default mode (GetUsedAssemblyReferences) keeps the reference; symbol-based flagged it removable; removing it produced 39CS0012errors.Fix
Add a
TrackOverriddenChainhelper that walksOverriddenMethod/OverriddenProperty/OverriddenEventchains and tracks every containing assembly. Call it from theIInvocationOperation(TargetMethod) andIMemberReferenceOperation(Member) branches insideRegisterOperationAction. Fields don't have override chains, so they're skipped via the type switch.Distinct from #141 and #142
Foo.StaticMethod()whereStaticMethodis inherited - trackFoo's assembly). Override chains are the symmetric direction: the override is the ""near"" symbol, the base is the ""far"" assembly that needs tracking.INamedTypeSymbolbranch onRegisterSymbolAction. Override-chain gap fires on instance member access inRegisterOperationAction, not on type declarations.Tests
Five new regression tests in
AnalyzerTests, all of which fail without this change:UsedViaOverridePropertyAccess-- canonical scenario from the QB trialUsedViaOverrideMethodCall-- method variantUsedViaOverrideEventAccess-- event variantUsedViaOverrideMultiLevelChain-- three-level A -> B -> C chain ensures the loop walks past the immediate overrideUnrelatedReferenceNotMarkedByOverride-- negative test ensuring the fix doesn't over-credit unrelated assembliesVerified by stashing the analyzer change and rerunning: every new test fails without the fix. Full suite: 147 / 150 pass; the 3 remaining failures are pre-existing C++ MSVC E2E tests unrelated to this change.
Out of scope
Implicit and explicit interface implementations have similar shape (compiler validates the implementation relationship) but use
ISymbol.ExplicitInterfaceImplementations/FindImplementationForInterfaceMemberrather thanOverriddenX. The QB trial did not produce a clear repro for that case, so it's deliberately not addressed here. If a real-world repro surfaces it should be a separate fix.