Re: [v2 of PATCH 08/14] cp/tree.c: strip location wrappers in lvalue_kind

[Jason Merrill <jason at redhat dot com>]

On Wed, Dec 20, 2017 at 5:14 PM, David Malcolm <dmalcolm@redhat.com> wrote:
> On Mon, 2017-12-11 at 18:39 -0500, Jason Merrill wrote:
>> On 11/10/2017 04:45 PM, David Malcolm wrote:
>> > Without this, then lvalue_p returns false for decls, and hence
>> > e.g. uses of them for references fail.
>> >
>> > Stripping location wrappers in lvalue_kind restores the correct
>> > behavior of lvalue_p etc.
>> >
>> > gcc/cp/ChangeLog:
>> >     * tree.c (lvalue_kind): Strip any location wrapper.
>>
>> Rather, lvalue_kind should learn to handle VIEW_CONVERT_EXPR.

> This patch does so, using:
>
>     case NON_LVALUE_EXPR:
>     case VIEW_CONVERT_EXPR:
>       if (location_wrapper_p (ref))
>         return lvalue_kind (TREE_OPERAND (ref, 0));
>
> As well as the VIEW_CONVERT_EXPR, lvalue_kind needs to handle
> NON_LVALUE_EXPR, otherwise a location-wrapped string literal
> hits this clause in the "default" case:
>
>       if (CLASS_TYPE_P (TREE_TYPE (ref))
>           || TREE_CODE (TREE_TYPE (ref)) == ARRAY_TYPE)
>         return clk_class;
>
> when it should have hit this one (after removing the
> location wrapper):
>
>     case STRING_CST:
>     case COMPOUND_LITERAL_EXPR:
>       return clk_ordinary;

Ah, the issue is that string literals should use VIEW_CONVERT_EXPR
rather than NON_LVALUE_EXPR, since they are lvalues.  With that
change, we shouldn't need to handle NON_LVALUE_EXPR specifically.

Jason