[Flang] Address review comments.

Author: DanielCChen

flang/lib/Lower/ConvertCall.cpp

@@ -924,16 +924,19 @@ static PreparedDummyArgument preparePresentUserCallActualArgument(
   if (hlfir::isFortranProcedureValue(dummyType)) {
     // Procedure pointer or function returns procedure pointer actual to
     // procedure dummy.
-    if (actual.isProcedurePointer() ||
-        actual.getType().isa<fir::BoxProcType>()) {
+    if (actual.isProcedurePointer()) {
       actual = hlfir::derefPointersAndAllocatables(loc, builder, actual);
       return PreparedDummyArgument{actual, /*cleanups=*/{}};
     }
     // Procedure actual to procedure dummy.
     assert(actual.isProcedure());
     // Do nothing if this is a procedure argument. It is already a
     // fir.boxproc/fir.tuple<fir.boxproc, len> as it should.
-    if (actual.getType() != dummyType)
+    if (!actual.getType().isa<fir::BoxProcType>() &&
+        actual.getType() != dummyType)
+      // The actual argument may be a procedure that returns character (a
+      // fir.tuple<fir.boxproc, len>) while the dummy is not. Extract the tuple
+      // in that case.
       actual = fixProcedureDummyMismatch(loc, builder, actual, dummyType);
     return PreparedDummyArgument{actual, /*cleanups=*/{}};
   }