Swift: synthesize CaptureListExpr::getVariable in QL instead of extracting it

Author: redsun82

swift/extractor/translators/ExprTranslator.cpp

@@ -119,7 +119,6 @@ codeql::CaptureListExpr ExprTranslator::translateCaptureListExpr(
   entry.closure_body = dispatcher.fetchLabel(expr.getClosureBody());
   for (const auto& item : const_cast<swift::CaptureListExpr&>(expr).getCaptureList()) {
     entry.binding_decls.push_back(dispatcher.fetchLabel(item.PBD));
-    entry.variables.push_back(dispatcher.fetchLabel(item.getVar()));
   }
   return entry;
 }

swift/ql/.generated.list

@@ -1,5 +1,11 @@
 private import codeql.swift.generated.expr.CaptureListExpr
+private import codeql.swift.elements.decl.VarDecl
+private import codeql.swift.elements.pattern.NamedPattern
 
 class CaptureListExpr extends Generated::CaptureListExpr {
   override string toString() { result = this.getClosureBody().toString() }
+
+  override VarDecl getVariable(int index) {
+    result = this.getBindingDecl(index).getPattern(0).(NamedPattern).getVarDecl()
+  }
 }

swift/ql/lib/codeql/swift/elements/expr/CaptureListExpr.qll

@@ -411,7 +411,9 @@ class CapturedDecl(Decl):
 
 class CaptureListExpr(Expr):
     binding_decls: list[PatternBindingDecl] | child
-    variables: list[VarDecl] | child
+    variables: list[VarDecl] | child | synth | desc("""
+        These are the variables introduced by this capture in the closure's scope, not the captured ones.
+    """)
     closure_body: "ClosureExpr" | child
 
 class CollectionExpr(Expr):