unified: Simplify uncertain scopes

Marking Members as uncertain scopes led to inaccurate resolution when a member referred to itself, because the uncertain scope (Member) appeared in the scope chain before the LocalName scope (ClassLikeDeclaration).

Meanwhile, one of the arguments for doing it, avoiding base classes etc from hitting the uncertain scope, was already fixed by local scope tree-rewrites.

It gets harder to detect if a given access appears in static or instance context, but perhaps we'll probably want to expose such information through a separate predicate anyway.

Author: asgerf

unified/ql/lib/codeql/unified/internal/LocalNameBinding.qll

@@ -317,11 +317,7 @@ private module LocalNameBindingInput implements LocalNameBindingInputSig<Locatio
 
   predicate uncertainScope(AstNode scope) {
     // Classes can have uncertain members due to unqualified access to inherited members.
-    // Instead of marking the whole class scope as uncertain, we mark its individual members, for two reasons:
-    // - Base types and type parameter constraints will then not resolve through the uncertain scope.
-    // - It becomes easy to determine if a given uncertain lookup appears in instance context or static context
-    //   because the associated uncertain scope is a Member, from which we can check static-ness.
-    scope = any(ClassLikeDeclaration cls).getAMember()
+    scope = any(ClassLikeDeclaration cls)
     or
     scope = any(TopLevel t).getBody() // Imported names are in scope here
     or

unified/ql/lib/codeql/unified/internal/StaticNameBinding.qll

@@ -118,14 +118,7 @@ NameBindingNode getModuleNodeFromFile(File f) {
 }
 
 /** Gets the name-binding node associated with the given uncertain scope node. */
-private NameBindingNode getNodeFromUncertainScope(AstNode n) {
-  exists(ClassLikeDeclaration cls |
-    n = cls.getAMember() and // note: must align with LocalNameBindingInput::uncertainScope
-    result.isLocalNamespace(cls)
-  )
-  or
-  result.isLocalNamespace(n)
-}
+private NameBindingNode getNodeFromUncertainScope(AstNode n) { result.isLocalNamespace(n) }
 
 predicate readStep(NameBindingNode node1, string name, NameBindingNode node2) {
   exists(MemberAccessExpr expr |