unified: Change plugin hook to isNonPattern

Author: asgerf

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

@@ -185,8 +185,20 @@ private module LocalNameBindingInput implements LocalNameBindingInputSig<Locatio
     override AstNode getElse() { none() }
   }
 
+  /** Holds if `e` cannot be a pattern even if it appears in pattern context. */
+  bindingset[e]
+  private predicate isNonPattern(Expr e) {
+    e = any(TypeTestExpr n).getType()
+    or
+    e = any(TypeCastExpr n).getType()
+    or
+    e instanceof MemberAccessExpr
+    or
+    any(NameBindingPlugin p).isNonPattern(e)
+  }
+
   additional predicate bindingContext(AstNode pattern, AstNode scope, AstNode declaration) {
-    not any(NameBindingPlugin p).isNameReferenceInPatternContext(pattern) and
+    not isNonPattern(pattern) and
     (
       exists(SiblingShadowingDecl decl |
         scope = decl and

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

@@ -5,12 +5,11 @@ 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, refers to an existing name.
-   *
-   * The caller has already restricted `identifier` to one that appears in pattern context.
+   * Holds if `e`, occurring in pattern context, should be interpreted a sub-expression
+   * whose result is to be compared to the incoming value.
    */
-  bindingset[identifier]
-  predicate isNameReferenceInPatternContext(Identifier identifier) { none() }
+  bindingset[e]
+  predicate isNonPattern(Expr e) { none() }
 
   /**
    * Holds if `member` is an instance member.

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

@@ -6,10 +6,8 @@ private import unified
 private import codeql.unified.internal.NameBindingPlugin
 
 class NameBindingPluginSwift extends NameBindingPlugin {
-  bindingset[identifier]
-  override predicate isNameReferenceInPatternContext(Identifier identifier) {
-    isUnboundPattern(identifier)
-  }
+  bindingset[e]
+  override predicate isNonPattern(Expr e) { isUnboundPattern(e.(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]