C++: test for fold expressions

cpp/ql/test/library-tests/fold/fold.cpp

@@ -0,0 +1,28 @@
+// semmle-extractor-options: --edg --c++17
+
+template<typename ...Args>
+int sum(Args&&... args) {
+  return (args + ...);
+}
+
+template<typename ...Args>
+int product(Args&&... args) {
+  return (... * args);
+}
+
+template<typename ...Args>
+bool all(Args&&... args) {
+  return (args && ... && true);
+}
+
+template<typename ...Args>
+bool any(Args&&... args) {
+  return (false || ... || args);
+}
+
+void f() {
+  int x = sum(1, 2, 3, 4, 5);
+  int y = product(2, 4, 6, 8);
+  bool a = all(true, true, false, true);
+  bool b = any(false, true, false, false);
+}

cpp/ql/test/library-tests/fold/fold.expected

@@ -0,0 +1,4 @@
+| fold.cpp:5:10:5:21 | ( pack + ... ) | + | fold.cpp:5:11:5:14 | args | <no init> |
+| fold.cpp:10:10:10:21 | ( ... * pack ) | * | fold.cpp:10:17:10:20 | args | <no init> |
+| fold.cpp:15:10:15:30 | ( pack && ... && init ) | && | fold.cpp:15:11:15:14 | args | 1 |
+| fold.cpp:20:10:20:31 | ( init \|\| ... \|\| pack ) | \|\| | fold.cpp:20:27:20:30 | args | 0 |

cpp/ql/test/library-tests/fold/fold.ql

@@ -0,0 +1,7 @@
+import cpp
+
+from FoldExpr fe, Expr pack, string init
+where
+  pack = fe.getPackExpr() and
+  if fe.hasInitExpr() then init = fe.getInitExpr().toString() else init = "<no init>"
+select fe, fe.getOperatorString(), pack, init