[C++-0x] User defined literals.

Ed Smith-Rowland 3dw4rd@verizon.net
Wed Jul 20 22:09:00 GMT 2011


On 07/12/2011 04:56 PM, Jason Merrill wrote:
> A few more notes:
>
>> +      if (DECL_NAMESPACE_SCOPE_P (decl))
>> +       {
>> +         if (!check_literal_operator_args(decl,
>> + &long_long_unsigned_p, &long_double_p))
>> +           {
>> +             error ("%qD has illegal argument list", decl);
>> +             return NULL_TREE;
>> +           }
>> +
>> +         if (CP_DECL_CONTEXT (decl) == global_namespace)
>> +           {
>> +             const char *suffix = UDLIT_OP_SUFFIX (DECL_NAME (decl));
>> +             if (long_long_unsigned_p)
>> +               {
>> +                 if (cpp_interpret_int_suffix (suffix, strlen 
>> (suffix)))
>> +                   warning (0, "integer suffix shadowed by 
>> implementation");
>> +               }
>> +             else if (long_double_p)
>> +               {
>> +                 if (cpp_interpret_float_suffix (suffix, strlen 
>> (suffix)))
>> +                   warning (0, "floating point suffix"
>> +                               " shadowed by implementation");
>> +               }
>> +           }
>> +       }
>
> Doesn't the shadowing apply everywhere, not just at file scope?
>
>> +  if (cpp_userdef_string_p (tok->type))
>> +    {
>> +      string_tree = USERDEF_LITERAL_VALUE (tok->u.value);
>> +      tok->type = cpp_userdef_string_remove_type (tok->type);
>> +      curr_tok_is_userdef_p = true;
>> +    }
>
> It seems like a mistake to change tok->type without changing the 
> value.  Why not just set the 'type' local variable appropriately?
>
>> +             const char *curr_suffix = IDENTIFIER_POINTER (suffix_id);
>> +             if (have_suffix_p == 0)
>> +               {
>> +                 suffix = xstrdup (curr_suffix);
>> +                 have_suffix_p = 1;
>> +               }
>> +             else if (have_suffix_p == 1 && strcmp (suffix, 
>> curr_suffix) != 0)
> ...
>> +         USERDEF_LITERAL_SUFFIX_ID (literal) = get_identifier (suffix);
>
> Just remember the identifier and compare it with ==.  Identifiers are 
> unique.
>
>> +  /* Lookup the name we got back from the id-expression.  */
>> +  decl = cp_parser_lookup_name (parser, name,
>
> Maybe use lookup_function_nonclass?
>
> Jason
>
>
I was conflating shadowing because of the preprocessor capturing 
suffixed like F for float and L for long int, etc. (which are captured 
by te preprocessor for those purposes) with allowing two user-specified 
suffixes to be disambiguated with namespaces and using declarations as 
mentioned in the paper.

I removed those tests.

Now I have a real question:  Since a shadowed suffix *cannot* act like 
the user wants no matter what, should I error instead of warn?



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