Swift: Cover additional edge case.

Author: geoffw0

swift/ql/lib/codeql/swift/dataflow/ExternalFlow.qll

@@ -434,7 +434,9 @@ private Element interpretElement0(
       subtypes = true and
       declWithMethod.getNominalTypeDecl() = namedTypeDecl.getADerivedTypeDecl*()
       or
-      exists(ExtensionDecl e | e.getExtendedTypeDecl() = declWithMethod.getNominalTypeDecl() |
+      exists(ExtensionDecl e |
+        e.getExtendedTypeDecl().getADerivedTypeDecl*() = declWithMethod.getNominalTypeDecl()
+      |
         subtypes = true and
         e.getAProtocol() = namedTypeDecl.getADerivedTypeDecl*()
       )
@@ -454,7 +456,9 @@ private Element interpretElement0(
       subtypes = true and
       declWithField.getNominalTypeDecl() = namedTypeDecl.getADerivedTypeDecl*()
       or
-      exists(ExtensionDecl e | e.getExtendedTypeDecl() = declWithField.getNominalTypeDecl() |
+      exists(ExtensionDecl e |
+        e.getExtendedTypeDecl().getADerivedTypeDecl*() = declWithField.getNominalTypeDecl()
+      |
         subtypes = true and
         e.getAProtocol() = namedTypeDecl.getADerivedTypeDecl*()
       )

swift/ql/test/library-tests/dataflow/flowsources/FlowSources.expected

@@ -74,6 +74,7 @@
 | generics.swift:132:9:132:15 | .source1 | external |
 | generics.swift:133:9:133:15 | .source2 | external |
 | generics.swift:162:9:162:22 | call to source2() | external |
+| generics.swift:163:9:163:22 | call to source3() | external |
 | nsdata.swift:18:17:18:40 | call to NSData.init(contentsOf:) | external |
 | nsdata.swift:19:17:19:53 | call to NSData.init(contentsOf:options:) | external |
 | string.swift:56:21:56:44 | call to String.init(contentsOf:) | external |

swift/ql/test/library-tests/dataflow/flowsources/generics.swift

@@ -160,5 +160,5 @@ class MyChildClass3: MyClass3 {
 func useProtocol3(impl: MyChildClass3) {
     _ = impl.source1() // not a source (`MyProtocol3.source1` is the declared source and `MyParentClass3` doesn't extend it)
     _ = impl.source2() // SOURCE
-    _ = impl.source3() // SOURCE [NOT DETECTED]
+    _ = impl.source3() // SOURCE
 }