[Bug debug/55641] debug info for the type of a reference declared with a typedef has spurious 'const'

[tromey at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55641

--- Comment #9 from Tom Tromey <tromey at gcc dot gnu.org> ---
I think this happens due to this code in gen_variable_die:

      tree type = TREE_TYPE (decl_or_origin);

      if (decl_by_reference_p (decl_or_origin))
    add_type_attribute (var_die, TREE_TYPE (type), 0, 0, context_die);
      else
    add_type_attribute (var_die, type, TREE_READONLY (decl_or_origin),
                TREE_THIS_VOLATILE (decl_or_origin), context_die);

For the reduced test case we enter the second call to add_type_attribute.
"g" is marked as TREE_READONLY, so this forces the "const" to be emitted.

Is there ever a case where this is correct?  That is, where the DWARF
needs to emit "const" or "volatile" but the only note is on the object
and not the object's type?  I didn't know.