Swift: extract DiscardStmt

Author: AlexDenisov

swift/extractor/infra/SwiftTagTraits.h

@@ -61,9 +61,7 @@ MAP(swift::Stmt, StmtTag)
   MAP(swift::FailStmt, FailStmtTag)
   MAP(swift::ThrowStmt, ThrowStmtTag)
   MAP(swift::PoundAssertStmt, PoundAssertStmtTag)
-#if CODEQL_SWIFT_VERSION_GE(5, 9)
-  MAP(swift::DiscardStmt, void) // TODO (introduced in 5.9)
-#endif
+  MAP(swift::DiscardStmt, DiscardStmtTag)
 
 MAP(swift::Argument, ArgumentTag)
 MAP(swift::KeyPathExpr::Component, KeyPathComponentTag)

swift/extractor/translators/StmtTranslator.cpp

@@ -212,4 +212,10 @@ codeql::PoundAssertStmt StmtTranslator::translatePoundAssertStmt(
   return entry;
 }
 
+codeql::DiscardStmt StmtTranslator::translateDiscardStmt(const swift::DiscardStmt& stmt) {
+  auto entry = dispatcher.createEntry(stmt);
+  entry.sub_expr = dispatcher.fetchLabel(stmt.getSubExpr());
+  return entry;
+}
+
 }  // namespace codeql

swift/extractor/translators/StmtTranslator.h

@@ -39,6 +39,7 @@ class StmtTranslator : public AstTranslatorBase<StmtTranslator> {
   codeql::YieldStmt translateYieldStmt(const swift::YieldStmt& stmt);
   codeql::FailStmt translateFailStmt(const swift::FailStmt& stmt);
   codeql::PoundAssertStmt translatePoundAssertStmt(const swift::PoundAssertStmt& stmt);
+  codeql::DiscardStmt translateDiscardStmt(const swift::DiscardStmt& stmt);
 
  private:
   void fillLabeledStmt(const swift::LabeledStmt& stmt, codeql::LabeledStmt& entry);

swift/ql/.generated.list

@@ -237,6 +237,14 @@ module Stmts {
     }
   }
 
+  private class DiscardStmtTree extends AstStandardPostOrderTree {
+    override DiscardStmt ast;
+
+    final override ControlFlowElement getChildElement(int i) {
+      i = 0 and result.asAstNode() = ast.getSubExpr().getFullyUnresolved()
+    }
+  }
+
   private class YieldStmtTree extends AstStandardPostOrderTree {
     override YieldStmt ast;