[flang] Avoid null pointer dereference

Original-commit: flang-compiler/f18@3c108c0edcdbf67e75039ddcefba74598905e87c
Reviewed-on: https://github.com/flang-compiler/f18/pull/553
Tree-same-pre-rewrite: false

diff --git a/flang/lib/evaluate/type.cc b/flang/lib/evaluate/type.cc
index 047e3b7..f98cdcc 100644 (file)
--- a/flang/lib/evaluate/type.cc
+++ b/flang/lib/evaluate/type.cc
@@ -174,7 +174,7 @@ bool DynamicType::IsTkCompatibleWith(const DynamicType &that) const {
   } else if (!derived_ || !that.derived_ ||
       !IsKindCompatible(*derived_, *that.derived_)) {
     return false;  // kind params don't match
-  } else if (!IsPolymorphic()) {
+  } else if (!IsPolymorphic() && that.derived_ != nullptr) {
     return derived_->typeSymbol() == that.derived_->typeSymbol();
   } else {
     return IsAncestorTypeOf(derived_, that.derived_);