C++: Support C++20 range-based for initializers

cpp/downgrades/298438feb146335af824002589cd6d4e96e5dbf9/exprparents.ql

@@ -0,0 +1,19 @@
+class Element extends @element {
+  string toString() { none() }
+}
+
+class Expr extends @expr {
+  string toString() { none() }
+}
+
+class Stmt extends @stmt {
+  string toString() { none() }
+}
+
+predicate isStmtWithInitializer(Stmt stmt) { exists(int kind | stmts(stmt, kind, _) | kind = 29) }
+
+from Expr child, int index, int index_new, Element parent
+where
+  exprparents(child, index, parent) and
+  if isStmtWithInitializer(parent) then index_new = index - 1 else index_new = index
+select child, index_new, parent

cpp/downgrades/298438feb146335af824002589cd6d4e96e5dbf9/for_initialization.ql

@@ -0,0 +1,9 @@
+class Stmt extends @stmt {
+  string toString() { none() }
+}
+
+from Stmt f, Stmt i
+where
+  for_initialization(f, i) and
+  f instanceof @stmt_for
+select f, i

cpp/downgrades/298438feb146335af824002589cd6d4e96e5dbf9/stmtparents.ql

@@ -0,0 +1,20 @@
+class Element extends @element {
+  string toString() { none() }
+}
+
+class Stmt extends @stmt {
+  string toString() { none() }
+}
+
+predicate isStmtWithInitializer(Stmt stmt) { exists(int kind | stmts(stmt, kind, _) | kind = 29) }
+
+from Stmt child, int index, int index_new, Element parent
+where
+  stmtparents(child, index, parent) and
+  (
+    not isStmtWithInitializer(parent)
+    or
+    index > 0
+  ) and
+  if isStmtWithInitializer(parent) then index_new = index - 1 else index_new = index
+select child, index_new, parent

cpp/downgrades/298438feb146335af824002589cd6d4e96e5dbf9/upgrade.properties

@@ -0,0 +1,5 @@
+description: Support C++20 range-based for initializers
+compatibility: partial
+exprparents.rel: run exprparents.qlo
+stmtparents.rel: run stmtparents.qlo
+for_initialization.rel: run for_initialization.qlo