[flang] Keep current polymorphic implementation under a flag

It is useful for couple of test suite like NAG to keep failing
with a TODO until the polymorphic entities is implemented  all the
way done to codegen.

This pass adds a flag to LoweringOptions for experimental development.
This flag is off by default and can be enable in `bbc` with `-polymorphic-type`.
Options can be added in the driver and tco when needed.

Reviewed By: PeteSteinfeld

Differential Revision: https://reviews.llvm.org/D135283

1 files changed, 6 insertions, 0 deletions

diff --git a/flang/lib/Lower/CallInterface.cpp b/flang/lib/Lower/CallInterface.cpp
index 510cb60..d482859 100644
--- a/flang/lib/Lower/CallInterface.cpp
+++ b/flang/lib/Lower/CallInterface.cpp
@@ -797,6 +797,12 @@ private:
     Fortran::common::TypeCategory cat = dynamicType.category();
     // DERIVED
     if (cat == Fortran::common::TypeCategory::Derived) {
+      // TODO is kept under experimental flag until feature is complete.
+      if (dynamicType.IsPolymorphic() &&
+          !getConverter().getLoweringOptions().isPolymorphicTypeImplEnabled())
+        TODO(interface.converter.getCurrentLocation(),
+             "support for polymorphic types");
+
       if (dynamicType.IsUnlimitedPolymorphic())
         return mlir::NoneType::get(&mlirContext);
       return getConverter().genType(dynamicType.GetDerivedTypeSpec());