Dependencies: references in generic signatures create public dependencies.

Noticed by inspection (!). This logic could use some before/after fuzzing.

Author: jrose-apple

lib/Sema/TypeCheckType.cpp

@@ -746,7 +746,7 @@ resolveTopLevelIdentTypeComponent(TypeChecker &TC, DeclContext *DC,
       }
     }
 
-    if (!DC->isCascadingContextForLookup(/*excludeFunctions*/true))
+    if (!DC->isCascadingContextForLookup(/*excludeFunctions*/false))
       options |= TR_KnownNonCascadingDependency;
 
     // The remaining lookups will be in the parent context.

test/NameBinding/Inputs/reference-dependencies-helper.swift

@@ -133,3 +133,6 @@ struct OtherFileTypeToBeExtended {}
 
 struct TypeReferencedOnlyBySubscript {}
 struct TypeReferencedOnlyByPrivateSubscript {}
+
+protocol ProtoReferencedOnlyInGeneric {}
+protocol ProtoReferencedOnlyInPrivateGeneric {}

test/NameBinding/reference-dependencies.swift

@@ -326,6 +326,12 @@ private struct PrivateTy6 {}
 // CHECK-DAG: !private "PrivateProto3"
 extension PrivateTy6 : PrivateProto3 {}
 
+// CHECK-DAG: - "ProtoReferencedOnlyInGeneric"
+func genericTest<T: ProtoReferencedOnlyInGeneric>(_: T) {}
+// CHECK-DAG: !private "ProtoReferencedOnlyInPrivateGeneric"
+// FIXME: Should be 
+private func privateGenericTest<T: ProtoReferencedOnlyInPrivateGeneric>(_: T) {}
+
 struct Sentinel1 {}
 
 private protocol ExtensionProto {}