swift: credit aliased type through typealias edge (v102)

handleTypeAlias now folds the RHS type in as a RelInstantiates edge,
so a type reached only through its alias name is no longer reported as
dead code. Guarded like handleInit; cacheVersion v102 + golden fixture.

Author: dejo1307

internal/cachecov/coverage_test.go

@@ -133,6 +133,7 @@ var versionCoverage = map[int][]string{
 	99: {"TestKtComplexity_CallsInScalingLoop_ConstantExcluded", "TestKtComplexity_CallsInScalingLoop_InfiniteLoopCallsRetained", "TestKtComplexity_CallsInScalingLoop_ScalingRetained", "TestKtComplexity_CallsInScalingLoop_MixedLoops", "TestKtComplexity_CallsInScalingLoop_AbsentWithoutLoopCalls", "TestExtract_CallsInScalingLoop_InfiniteLoopCallsRetained", "TestExtract_CallsInScalingLoop_PresentButEmptyWhenAllBounded", "TestExtract_CallsInScalingLoop_AbsentWithoutLoopCalls", "TestPyComplexity_CallsInScalingLoop_InfiniteLoopCallsRetained", "TestPyComplexity_CallsInScalingLoop_PresentButEmptyWhenAllBounded", "TestPyComplexity_CallsInScalingLoop_AbsentWithoutLoopCalls", "TestTsComplexity_CallsInScalingLoop_InfiniteLoopCallsRetained", "TestTsComplexity_CallsInScalingLoop_PresentButEmptyWhenAllBounded", "TestTsComplexity_CallsInScalingLoop_AbsentWithoutLoopCalls", "TestGolden"}, // calls_in_scaling_loop = repeated (not merely scaling) loops, emitted even when empty
 	100: {"TestExtractTestRefs_InPackageCallResolvesToProductionSymbol", "TestExtractTestRefs_ExternalTestPackageResolvesThroughImport", "TestExtractTestRefs_SkipsBuiltinsAndEmitsNoSymbols", "TestExtractTestRefs_IgnoresFilesItDoesNotOwn", "TestExtractTestRefs_ReferenceFreeFileYieldsNoFact", "TestDefaultTestGlobsCoverGoAndStayIgnored", "TestGolden"}, // Go test_ref facts: both gates, so a function called only from its _test.go is no longer high-confidence dead
 	101: {"TestGoHTTPClient_PackageConstAbsoluteBaseURL_TaggedExternalWithHost", "TestGoHTTPClient_PackageScopedConstFromSiblingFile_TaggedExternal", "TestGoHTTPClient_StructFieldAbsoluteBaseURL_TaggedExternalNoHostWhenAmbiguous", "TestGoHTTPClient_ConfigInjectedBaseURL_NotTaggedExternal", "TestGoHTTPClient_RelativeLiteralBaseURL_NotTaggedExternal", "TestGoHTTPClient_MixedAbsoluteAndRelativeBindings_NotTaggedExternal", "TestGoHTTPClient_RouteNameUnchangedByExternalTagging", "TestComputeLinks_ExternalClientStillMatchesLoadedServer", "TestGolden"}, // Go base-URL host recovery: third-party client calls tagged external, hardcoded internal host still resolves
+	102: {"TestTypeAlias_EmitsReferenceEdgeToUnderlyingType", "TestTypeAlias_FunctionTypeRHSEmitsNoEdge", "TestGolden"}, // Swift typealias folds the aliased type in as a RelInstantiates edge, so a type reached only through its alias name is not mis-reported as dead code
 }
 
 func TestCacheVersionCoverage(t *testing.T) {

internal/engine/cache.go

@@ -308,7 +308,14 @@ import (
 // snapshots must re-extract. (The paired linker change — matching a client route
 // before bucketing it external, so a hardcoded internal host still resolves — runs
 // post-extraction and needs no cache bump; it is covered by TestGolden here.)
-const cacheVersion = "v101"
+// v102: the Swift extractor folds a typealias's aliased type into the alias fact
+// as a RelInstantiates edge. `typealias FooViewModel = FooEditorState` used to
+// leave FooEditorState with no incoming edge, so a type reached only through its
+// alias name was mis-reported as unreferenced dead code (GAP-SW-09). handleTypeAlias
+// now emits the edge (guarded like handleInit — system types and function/tuple/
+// optional RHS shapes, which have no simple type name, emit nothing). Swift symbol
+// facts gain a relation, so cached Swift snapshots must re-extract.
+const cacheVersion = "v102"
 
 // extractorCache holds per-extractor facts keyed by a content hash of the files
 // the extractor depends on. It is loaded from disk at the start of a snapshot and

internal/engine/testdata/golden/swift_sample.facts.jsonl

@@ -1,3 +1,4 @@
+{"kind":"dependency","name":"Sources/CoreKit -\u003e Foundation","file":"Sources/CoreKit/Aliasing.swift","line":1,"repo":"swift_sample","props":{"language":"swift","source":"stdlib"},"relations":[{"kind":"imports","target":"Foundation"}]}
 {"kind":"dependency","name":"Sources/CoreKit -\u003e Foundation","file":"Sources/CoreKit/Endpoints.swift","line":1,"repo":"swift_sample","props":{"language":"swift","source":"stdlib"},"relations":[{"kind":"imports","target":"Foundation"}]}
 {"kind":"dependency","name":"Sources/CoreKit -\u003e Foundation","file":"Sources/CoreKit/Inheritance.swift","line":1,"repo":"swift_sample","props":{"language":"swift","source":"stdlib"},"relations":[{"kind":"imports","target":"Foundation"}]}
 {"kind":"dependency","name":"Sources/CoreKit -\u003e Foundation","file":"Sources/CoreKit/Networking.swift","line":1,"repo":"swift_sample","props":{"language":"swift","source":"stdlib"},"relations":[{"kind":"imports","target":"Foundation"}]}
@@ -10,6 +11,9 @@
 {"kind":"route","name":"feed/items","file":"Sources/CoreKit/Networking.swift","line":17,"repo":"swift_sample","props":{"api":"Networking","framework":"urlsession","language":"swift","method":"GET","role":"client","source":"urlsession"},"relations":[{"kind":"declares","target":"Sources/CoreKit"}]}
 {"kind":"symbol","name":"Sources/CoreKit.APIEndpoint","file":"Sources/CoreKit/Endpoints.swift","line":12,"repo":"swift_sample","props":{"exported":true,"language":"swift","symbol_kind":"interface"},"relations":[{"kind":"declares","target":"Sources/CoreKit"}]}
 {"kind":"symbol","name":"Sources/CoreKit.APIEndpoint.urlPrefixComponent","file":"Sources/CoreKit/Endpoints.swift","line":19,"repo":"swift_sample","props":{"cyclomatic":1,"exported":true,"language":"swift","symbol_kind":"variable"},"relations":[{"kind":"declares","target":"Sources/CoreKit"}]}
+{"kind":"symbol","name":"Sources/CoreKit.AliasName","file":"Sources/CoreKit/Aliasing.swift","line":11,"repo":"swift_sample","props":{"exported":true,"language":"swift","symbol_kind":"type"},"relations":[{"kind":"declares","target":"Sources/CoreKit"},{"kind":"instantiates","target":"Sources/CoreKit.AliasTarget"}]}
+{"kind":"symbol","name":"Sources/CoreKit.AliasTarget","file":"Sources/CoreKit/Aliasing.swift","line":7,"repo":"swift_sample","props":{"exported":true,"language":"swift","signature":"func perform()","symbol_kind":"class"},"relations":[{"kind":"declares","target":"Sources/CoreKit"}]}
+{"kind":"symbol","name":"Sources/CoreKit.AliasTarget.perform","file":"Sources/CoreKit/Aliasing.swift","line":8,"repo":"swift_sample","props":{"cyclomatic":1,"exported":true,"language":"swift","receiver":"AliasTarget","symbol_kind":"method"},"relations":[{"kind":"declares","target":"Sources/CoreKit"}]}
 {"kind":"symbol","name":"Sources/CoreKit.DataModel","file":"Sources/CoreKit/Inheritance.swift","line":4,"repo":"swift_sample","props":{"exported":true,"language":"swift","signature":"func runRequest()","symbol_kind":"class"},"relations":[{"kind":"declares","target":"Sources/CoreKit"}]}
 {"kind":"symbol","name":"Sources/CoreKit.DataModel.runRequest","file":"Sources/CoreKit/Inheritance.swift","line":5,"repo":"swift_sample","props":{"cyclomatic":1,"exported":true,"language":"swift","receiver":"DataModel","symbol_kind":"method"},"relations":[{"kind":"declares","target":"Sources/CoreKit"}]}
 {"kind":"symbol","name":"Sources/CoreKit.FeedService","file":"Sources/CoreKit/Networking.swift","line":8,"repo":"swift_sample","props":{"exported":true,"final":true,"language":"swift","signature":"let baseURL: URL\nfunc fetchFeed() async throws -\u003e Data\nfunc loadFeed() async throws -\u003e Data","symbol_kind":"class"},"relations":[{"kind":"declares","target":"Sources/CoreKit"}]}
@@ -29,5 +33,6 @@
 {"kind":"symbol","name":"Sources/CoreKit.TreeWalker.walk","file":"Sources/CoreKit/Recursion.swift","line":10,"repo":"swift_sample","props":{"cyclomatic":2,"exported":true,"language":"swift","receiver":"TreeWalker","recursive_self":true,"symbol_kind":"method"},"relations":[{"kind":"calls","target":"Sources/CoreKit.TreeWalker.walk"},{"kind":"declares","target":"Sources/CoreKit"}]}
 {"kind":"symbol","name":"Sources/CoreKit.UserModel","file":"Sources/CoreKit/Inheritance.swift","line":13,"repo":"swift_sample","props":{"exported":true,"final":true,"language":"swift","signature":"func refresh()","symbol_kind":"class"},"relations":[{"kind":"declares","target":"Sources/CoreKit"},{"kind":"implements","target":"DataModel"}]}
 {"kind":"symbol","name":"Sources/CoreKit.UserModel.refresh","file":"Sources/CoreKit/Inheritance.swift","line":14,"repo":"swift_sample","props":{"cyclomatic":1,"exported":true,"language":"swift","receiver":"UserModel","symbol_kind":"method"},"relations":[{"kind":"calls","target":"Sources/CoreKit.DataModel.runRequest"},{"kind":"declares","target":"Sources/CoreKit"}]}
+{"kind":"symbol","name":"Sources/CoreKit.useAlias","file":"Sources/CoreKit/Aliasing.swift","line":13,"repo":"swift_sample","props":{"cyclomatic":1,"exported":true,"language":"swift","symbol_kind":"function"},"relations":[{"kind":"calls","target":"Sources/CoreKit.AliasTarget.perform"},{"kind":"declares","target":"Sources/CoreKit"},{"kind":"instantiates","target":"AliasName"}]}
 {"kind":"symbol","name":"Tests/CoreKitTests.CoreKitTests","file":"Tests/CoreKitTests/CoreKitTests.swift","line":7,"repo":"swift_sample","props":{"exported":true,"final":true,"language":"swift","signature":"func testNodeHasNoParentByDefault()","symbol_kind":"class"},"relations":[{"kind":"declares","target":"Tests/CoreKitTests"},{"kind":"implements","target":"XCTestCase"}]}
 {"kind":"symbol","name":"Tests/CoreKitTests.CoreKitTests.testNodeHasNoParentByDefault","file":"Tests/CoreKitTests/CoreKitTests.swift","line":8,"repo":"swift_sample","props":{"cyclomatic":1,"exported":true,"language":"swift","receiver":"CoreKitTests","symbol_kind":"method"},"relations":[{"kind":"declares","target":"Tests/CoreKitTests"},{"kind":"instantiates","target":"Sources/CoreKit.Node"},{"kind":"instantiates","target":"XCTAssertNil"}]}

internal/engine/testdata/repos/swift_sample/Sources/CoreKit/Aliasing.swift

@@ -0,0 +1,16 @@
+import Foundation
+
+// AliasTarget is reached only through the AliasName typealias, so the alias must
+// credit it or the dead-code detector reports it as an unreferenced orphan
+// (GAP-SW-09, cache.go v102). handleTypeAlias folds the aliased type in as an
+// instantiation edge on the alias fact.
+class AliasTarget {
+    func perform() {}
+}
+
+typealias AliasName = AliasTarget
+
+func useAlias() {
+    let t = AliasName()
+    t.perform()
+}

internal/extractors/swiftextractor/swift_ast.go

@@ -1016,6 +1016,20 @@ func (w *astWalker) handleTypeAlias(node *sitter.Node) {
 		return
 	}
 	modifiers := findChildByKind(node, "modifiers")
+	relations := []facts.Relation{
+		{Kind: facts.RelDeclares, Target: w.dir},
+	}
+	// A `typealias Foo = Bar` is a genuine reference to Bar, so fold the aliased
+	// type in as an instantiation edge: a type reached only through its alias name
+	// (the idiomatic `typealias FooViewModel = FooEditorState`) would otherwise have
+	// no incoming edge and be mis-reported as an unreferenced orphan (GAP-SW-09).
+	// Mirrors handleInit's type guard — skip system types and function/tuple/
+	// optional RHS shapes, which yield no simple resolvable type name.
+	if valueNode := node.ChildByFieldName("value"); valueNode != nil {
+		if target := simpleTypeName(valueNode, w.src); target != "" && !isSystemType(target) && isTypeName(target) {
+			relations = append(relations, facts.Relation{Kind: facts.RelInstantiates, Target: target})
+		}
+	}
 	w.out = append(w.out, facts.Fact{
 		Kind: facts.KindSymbol,
 		Name: w.dir + "." + w.qualify(name),
@@ -1026,9 +1040,7 @@ func (w *astWalker) handleTypeAlias(node *sitter.Node) {
 			"exported":    !isPrivateAccess(nodeText(modifiers, w.src)),
 			"language":    "swift",
 		},
-		Relations: []facts.Relation{
-			{Kind: facts.RelDeclares, Target: w.dir},
-		},
+		Relations: relations,
 	})
 }
 

internal/extractors/swiftextractor/swift_typealias_test.go

@@ -0,0 +1,47 @@
+package swiftextractor
+
+import (
+	"testing"
+
+	"github.com/enola-labs/enola/internal/facts"
+)
+
+// TestTypeAlias_EmitsReferenceEdgeToUnderlyingType pins GAP-SW-09: a type reached
+// only through a `typealias` name must still credit the underlying declaration, or
+// the dead-code detector reports it as an unreferenced orphan. handleTypeAlias
+// folds the aliased type in as an instantiation edge on the alias fact.
+func TestTypeAlias_EmitsReferenceEdgeToUnderlyingType(t *testing.T) {
+	ff := extractAST(t, `
+class AliasTarget {
+    func perform() {}
+}
+typealias AliasName = AliasTarget
+`, false)
+
+	f, ok := findFact(ff, "pkg.AliasName")
+	if !ok {
+		t.Fatal("expected fact for pkg.AliasName")
+	}
+	if !hasRelation(f, facts.RelInstantiates, "AliasTarget") {
+		t.Errorf("expected typealias to reference underlying type AliasTarget; relations=%v", f.Relations)
+	}
+}
+
+// TestTypeAlias_FunctionTypeRHSEmitsNoEdge guards the fold: a function-type,
+// tuple, or otherwise unresolvable RHS yields no simple type name, so the alias
+// fact must carry no spurious reference edge.
+func TestTypeAlias_FunctionTypeRHSEmitsNoEdge(t *testing.T) {
+	ff := extractAST(t, `
+typealias Handler = (Int) -> Void
+`, false)
+
+	f, ok := findFact(ff, "pkg.Handler")
+	if !ok {
+		t.Fatal("expected fact for pkg.Handler")
+	}
+	for _, r := range f.Relations {
+		if r.Kind == facts.RelInstantiates || r.Kind == facts.RelCalls {
+			t.Errorf("did not expect a reference edge for a function-type alias; got %v", r)
+		}
+	}
+}