[flang] Fix potential null scope when lowering dispatch table op

[clementval]

Summary

Similary to D140209, the scope might need to be retrieved
from the typeSymbol. The test code was crashing because the
scope passed to CollectBindings was initially null.

flang/lib/Lower/Bridge.cpp

for (const DispatchTableInfo &info : registeredDispatchTableInfo) {
       std::string dtName = Fortran::lower::mangle::mangleName(*info.typeSpec);
       const Fortran::semantics::DerivedTypeSpec *parent =
           Fortran::evaluate::GetParentTypeSpec(*info.typeSpec);
       fir::FirOpBuilder &builder = converter.getFirOpBuilder();
       fir::DispatchTableOp dt = builder.createDispatchTableOp(
           info.loc, dtName,
           parent ? Fortran::lower::mangle::mangleName(*parent) : "");
       auto insertPt = builder.saveInsertionPoint();
-
+      const Fortran::semantics::Scope *scope = info.typeSpec->scope();
+      if (!scope)
+        scope = info.typeSpec->typeSymbol().scope();
       Fortran::semantics::SymbolVector bindings =
-          Fortran::semantics::CollectBindings(*info.typeSpec->scope());
+          Fortran::semantics::CollectBindings(*scope);
 
       if (!bindings.empty())
         builder.createBlock(&dt.getRegion());
 
       for (const Fortran::semantics::SymbolRef &binding : bindings) {
         const auto *details =
             binding.get().detailsIf<Fortran::semantics::ProcBindingDetails>();
         std::string bindingName =

flang/test/Lower/dispatch.f90

module call_dispatch
 
   type, abstract :: a1
     real :: a
     real :: b
   contains
     procedure(nopass_defferred), deferred, nopass :: nopassd
   end type
 
+  type :: node
+    type(node_ptr), pointer :: n(:)
+  end type
+  type :: use_node
+    type(node) :: n
+  end type
+  type :: node_ptr
+    type(node_ptr), pointer :: n
+  end type
+
   contains
 
 ! ------------------------------------------------------------------------------
 ! Test lowering of type-bound procedure call on polymorphic entities
 ! ------------------------------------------------------------------------------
 
     function p1_fct1_nopass()
       real :: p1_fct1_nopass
! ------------------------------------------------------------------------------
     end subroutine
 
 ! CHECK-LABEL: func.func @_QMcall_dispatchPcheck_nodispatch
 ! CHECK: fir.call @_QMcall_dispatchPtbp_nopass
 ! CHECK: fir.call @_QMcall_dispatchPtbp_pass
 ! CHECK: fir.call @_QMcall_dispatchPtbp_pass_arg0
 ! CHECK: fir.call @_QMcall_dispatchPtbp_pass_arg1
 
+  subroutine use_node_test(n)
+    type(use_node) :: n
+  end subroutine
+
 end module