[flang][debug] Support mlir::NoneType.

Author: abidh

flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp

@@ -516,6 +516,8 @@ DebugTypeGenerator::convertType(mlir::Type Ty, mlir::LLVM::DIFileAttr fileAttr,
     return convertPointerLikeType(elTy, fileAttr, scope, declOp,
                                   /*genAllocated=*/false,
                                   /*genAssociated=*/false);
+  } else if (mlir::isa<mlir::NoneType>(Ty)) {
+    return mlir::LLVM::DINullTypeAttr::get(context);
   } else if (auto boxTy = mlir::dyn_cast_or_null<fir::BoxType>(Ty)) {
     auto elTy = boxTy.getElementType();
     if (auto seqTy = mlir::dyn_cast_or_null<fir::SequenceType>(elTy))

flang/test/Transforms/debug-none-type.fir

@@ -0,0 +1,14 @@
+// RUN: fir-opt --add-debug-info --mlir-print-debuginfo %s | FileCheck %s
+
+module attributes {dlti.dl_spec = #dlti.dl_spec<>} {
+  func.func private @_FortranAAssign(i8) -> none loc(#loc1)
+  func.func private @foo() -> !fir.ref<none>  loc(#loc2)
+}
+#loc1 = loc("test.f90":5:1)
+#loc2 = loc("test.f90":15:1)
+
+// CHECK: #[[INT8_TY:.*]] = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "integer", sizeInBits = 8, encoding = DW_ATE_signed>
+// CHECK: #[[NONE_TY:.*]] = #llvm.di_null_type
+// CHECK: #[[REFNONE_TY:.*]] = #llvm.di_derived_type<tag = DW_TAG_pointer_type, name = "", baseType = #di_null_type{{.*}}>
+// CHECK: #llvm.di_subroutine_type<{{.*}}types = #[[NONE_TY]], #[[INT8_TY]]>
+// CHECK: #llvm.di_subroutine_type<{{.*}}types = #[[REFNONE_TY]]>