unified: Invert definition of plugin hook

Author: asgerf

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

@@ -189,15 +189,15 @@ private module LocalNameBindingInput implements LocalNameBindingInputSig<Locatio
     exists(SiblingShadowingDecl decl |
       scope = decl and
       pattern = decl.getPattern() and
-      (not pattern instanceof Identifier or any(NameBindingPlugin p).isNameDeclaration(pattern)) and
+      not any(NameBindingPlugin p).isNameReferenceInPatternContext(pattern) and
       declaration = decl
     )
     or
     exists(VariableDeclaration decl |
       not decl instanceof SiblingShadowingDecl and
       getChild(scope, _) = decl and
       pattern = decl.getPattern() and
-      (not pattern instanceof Identifier or any(NameBindingPlugin p).isNameDeclaration(pattern)) and
+      not any(NameBindingPlugin p).isNameReferenceInPatternContext(pattern) and
       declaration = decl
     )
     or
@@ -210,28 +210,28 @@ private module LocalNameBindingInput implements LocalNameBindingInputSig<Locatio
     exists(Parameter param |
       scope = param.getParent() and // TODO: add SourceCallable and use .getParameter() instead
       pattern = param.getPattern() and
-      (not pattern instanceof Identifier or any(NameBindingPlugin p).isNameDeclaration(pattern)) and
+      not any(NameBindingPlugin p).isNameReferenceInPatternContext(pattern) and
       declaration = param
     )
     or
     exists(CatchClause catch |
       scope = catch and // ensure both body and pattern are in scope
       pattern = catch.getPattern() and
-      (not pattern instanceof Identifier or any(NameBindingPlugin p).isNameDeclaration(pattern)) and
+      not any(NameBindingPlugin p).isNameReferenceInPatternContext(pattern) and
       declaration = catch
     )
     or
     exists(SwitchCase case |
       scope = case and // ensure both body and pattern are in scope
       pattern = case.getPattern() and
-      (not pattern instanceof Identifier or any(NameBindingPlugin p).isNameDeclaration(pattern)) and
+      not any(NameBindingPlugin p).isNameReferenceInPatternContext(pattern) and
       declaration = case
     )
     or
     exists(ForEachStmt stmt |
       scope = stmt and // ensure both 'body' and 'guard' are in scope
       pattern = stmt.getPattern() and
-      (not pattern instanceof Identifier or any(NameBindingPlugin p).isNameDeclaration(pattern)) and
+      not any(NameBindingPlugin p).isNameReferenceInPatternContext(pattern) and
       declaration = stmt
     )
     or
@@ -278,7 +278,7 @@ private module LocalNameBindingInput implements LocalNameBindingInputSig<Locatio
     )
     or
     bindingContext(getEnclosingPatternExpr(pattern.(Expr)), scope, declaration) and
-    (not pattern instanceof Identifier or any(NameBindingPlugin p).isNameDeclaration(pattern))
+    not any(NameBindingPlugin p).isNameReferenceInPatternContext(pattern)
   }
 
   private Expr getEnclosingPatternExpr(Expr child) {
@@ -405,7 +405,6 @@ class PotentialLocalNameAccess extends Identifier {
     this instanceof NameDeclaration
     or
     not this instanceof NameDeclaration and
-    not any(NameBindingPlugin p).isNameDeclaration(this) and
     not this = any(NamedPattern p).getIdentifier() and
     not this = any(MemberAccessExpr e).getMember() and
     not this = any(Argument a).getName() and

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

@@ -5,8 +5,8 @@ private import codeql.unified.internal.NameBindingPluginSwift // ensure override
 
 /** Extension point for language-specific inputs to name binding. */
 class NameBindingPlugin extends Unit {
-  /** Holds if `identifier`, occurring in pattern context, introduces a name. */
-  predicate isNameDeclaration(Identifier identifier) { none() }
+  /** Holds if `identifier`, occurring in pattern context, refers to an existing name. */
+  predicate isNameReferenceInPatternContext(Identifier identifier) { none() }
 
   /**
    * Holds if `member` is an instance member.

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

@@ -7,7 +7,9 @@ private import codeql.unified.internal.FacadeAst::Unified
 private import codeql.unified.internal.NameBindingPlugin
 
 class NameBindingPluginSwift extends NameBindingPlugin {
-  override predicate isNameDeclaration(Identifier identifier) { isInsideBindingPattern(identifier) }
+  override predicate isNameReferenceInPatternContext(Identifier identifier) {
+    not isInsideBindingPattern(identifier)
+  }
 
   // Note: For now we assume all code is Swift, but in the future we must restrict these rules to Swift-files
   bindingset[cls, member]
@@ -46,10 +48,7 @@ private predicate isInsideBindingPattern(AstNode child) {
     parent.hasModifier(["let", "var"])
   )
   or
-  exists(VariableDeclaration parent |
-    child = parent.getPattern() and
-    parent.hasModifier(["let", "var", "enum_case"])
-  )
+  child = any(VariableDeclaration parent).getPattern()
   or
   child = any(Parameter parent).getPattern()
   or