Update to C++17 and use std::optional for getSuperType (#4203)

This sets the C++ standard variable in the build to C++17, and makes use of std::optional (a C++17 library feature) in one place, to test that it's working.

1 files changed, 2 insertions, 3 deletions

diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 96a1abe73..34fe92ff6 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -2515,9 +2515,8 @@ struct PrintSExpression : public UnifiedExpressionVisitor<PrintSExpression> {
   }
   // Module-level visitors
   void printSupertypeOr(HeapType curr, std::string noSuper) {
-    HeapType super;
-    if (curr.getSuperType(super)) {
-      TypeNamePrinter(o, currModule).print(super);
+    if (auto super = curr.getSuperType()) {
+      TypeNamePrinter(o, currModule).print(*super);
     } else {
       o << noSuper;
     }