build_x_binary_op (ARRAY_REF ?!

[Alexey Starovoytov]

On Wed, 19 Apr 2006, Daniel Berlin wrote:

>
> On Apr 19, 2006, at 4:48 PM, Alexey Starovoytov wrote:
>
>> Hi,
>> 
>> Is this a bug that we were lucky not to hit?
>> 
>> cp/pt.c:
>>  return build_x_binary_op (ARRAY_REF, op1, RECUR (TREE_OPERAND (t, 1)),
>>                            /*overloaded_p=*/NULL);
>> tree
>> build_x_binary_op (enum tree_code code, tree arg1, tree arg2,
>>                   bool *overloaded_p)
>> {
>>  ...
>>  return build_min_nt (code, arg1, arg2);
>>  ...
>>  return build_min_non_dep (code, expr, orig_arg1, orig_arg2);
>> }
>> 
>> the 'code' for build_min* will still be ARRAY_REF, so both functions
>> have a chance to init ARRAY_REF with some junk:
>>  for (i = 0; i < length; i++)
>>    {
>>      tree x = va_arg (p, tree);
>>      TREE_OPERAND (t, i) = x;
>>    }
>
> The returned memory is memset in make_node in tree.c or thereabouts.
> IIRC.

make_node does memset, but the loop above is after the call to make_node.

I guess we didn't hit the problem just because tsubst_copy_and_build()
(where build_x_binary_op (ARRAY_REF is) is never called for array_ref 
when processing_template_decl is non zero.

I guess that sort of assertions need at least a comment or gcc_assert().

Alex.