Re: [C++ PATCH] Fix up -Wdeprecated (PR c++/84222)

[Jason Merrill <jason at redhat dot com>]

On Thu, Mar 15, 2018 at 4:07 AM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Wed, Mar 14, 2018 at 08:44:48PM -0400, Jason Merrill wrote:
>> > --- gcc/cp/decl.c.jj    2018-03-14 09:44:55.744974946 +0100
>> > +++ gcc/cp/decl.c       2018-03-14 12:18:08.094012453 +0100
>> > @@ -10448,7 +10448,7 @@ grokdeclarator (const cp_declarator *dec
>> >       suppress reports of deprecated items.  */
>> >    if (type && TREE_DEPRECATED (type)
>> >        && deprecated_state != DEPRECATED_SUPPRESS)
>> > -    warn_deprecated_use (type, NULL_TREE);
>> > +    cp_warn_deprecated_use (type);
>> >    if (type && TREE_CODE (type) == TYPE_DECL)
>> >      {
>> >        typedef_decl = type;
>> > @@ -10456,7 +10456,7 @@ grokdeclarator (const cp_declarator *dec
>> >        if (TREE_DEPRECATED (type)
>> >           && DECL_ARTIFICIAL (typedef_decl)
>> >           && deprecated_state != DEPRECATED_SUPPRESS)
>> > -       warn_deprecated_use (type, NULL_TREE);
>> > +       cp_warn_deprecated_use (type);
>> >      }
>> >    /* No type at all: default to `int', and set DEFAULTED_INT
>> >       because it was not a user-defined typedef.  */
>> > @@ -11271,8 +11271,18 @@ grokdeclarator (const cp_declarator *dec
>> >                   explicitp = 2;
>> >               }
>> >
>> > -           arg_types = grokparms (declarator->u.function.parameters,
>> > -                                  &parms);
>> > +           tree pushed_scope = NULL_TREE;
>> > +           if (funcdecl_p
>> > +               && decl_context != FIELD
>> > +               && inner_declarator->u.id.qualifying_scope
>> > +               && CLASS_TYPE_P (inner_declarator->u.id.qualifying_scope))
>> > +             pushed_scope
>> > +               = push_scope (inner_declarator->u.id.qualifying_scope);
>>
>> Can't we use ctype here?
>
> Inside of classes ctype is non-NULL, but we don't need to push anything,
> current_class_type is already the class we care about.
> That's the
>   tree ctype = current_class_type;
> on line 10130.  Then we have this
>   for (id_declarator = declarator;
>        id_declarator;
>        id_declarator = id_declarator->declarator)
> loop, where for cdk_id at line 10242 it tweaks ctype:
>                 else if (TYPE_P (qualifying_scope))
>                   {
>                     ctype = qualifying_scope;
>                     if (!MAYBE_CLASS_TYPE_P (ctype))
>                       {
>                         error ("%q#T is not a class or a namespace", ctype);
>                         ctype = NULL_TREE;
>                       }
> and indeed for the cases I care about (out of class method definitions)
> ctype is set to non-NULL here.  But then at line 10542 it is cleared again:
>   ctype = NULL_TREE;
>
> and at 11176:
>             if (ctype == NULL_TREE
>                 && decl_context == FIELD
>                 && funcdecl_p
>                 && friendp == 0)
>               ctype = current_class_type;
> set only for selected in-class definitions, and then tested and used a couple of
> times.  And that is the state we call grokparms with.
> Only later at line 11529 it is set again:
>   if (declarator
>       && declarator->kind == cdk_id
>       && declarator->u.id.qualifying_scope
>       && MAYBE_CLASS_TYPE_P (declarator->u.id.qualifying_scope))
>     {
>       ctype = declarator->u.id.qualifying_scope;
>       ctype = TYPE_MAIN_VARIANT (ctype);
> So, if I were to use some variable without really changing the behavior of
> the grokdeclarator massively, it would need to be a copy of ctype saved into
> another variable (how it should be named?) above line 10542.  Given the
> TYPE_MAIN_VARIANT, I guess we should be using TYPE_MAIN_VARIANT somewhere
> too.

Wow, yeah, the use of ctype in grokdeclarator is pretty bizarre.  Your
patch is OK.

Jason