Use (non-trivial) constructors for exprt/codet

This is more efficient, type safe, and easier to read.

Author: tautschnig

src/ansi-c/c_typecheck_expr.cpp

@@ -1270,8 +1270,7 @@ void c_typecheck_baset::typecheck_expr_index(exprt &expr)
     // p[i] is syntactic sugar for *(p+i)
 
     typecheck_arithmetic_pointer(expr.op0());
-    exprt addition(ID_plus, array_expr.type());
-    addition.operands().swap(expr.operands());
+    plus_exprt addition(exprt::operandst(expr.operands()), array_expr.type());
     expr.add_to_operands(std::move(addition));
     expr.id(ID_dereference);
     expr.set(ID_C_lvalue, true);

src/cpp/cpp_typecheck_conversions.cpp

@@ -1394,9 +1394,8 @@ bool cpp_typecheckt::reference_binding(
   {
     {
       // create temporary object
-      exprt tmp=exprt(ID_side_effect, type.subtype());
-      tmp.set(ID_statement, ID_temporary_object);
-      tmp.add_source_location()=expr.source_location();
+      side_effect_exprt tmp(
+        ID_temporary_object, type.subtype(), expr.source_location());
       // tmp.set(ID_C_lvalue, true);
       tmp.add_to_operands(std::move(new_expr));
       new_expr.swap(tmp);