```
bool
find_template_parameter_info::found (tree parm)
{
if (TREE_CODE (parm) == TREE_LIST)
parm = TREE_VALUE (parm);
if (TREE_CODE (parm) == TYPE_DECL)
parm = TREE_TYPE (parm);
else
parm = DECL_INITIAL (parm);
gcc_checking_assert (TEMPLATE_PARM_P (parm));
return parms.contains (parm);
}
```
Is there a reason why TREE_TYPE used only for TYPE_DECL, but not for
TEMPLATE_DECL ? process_template_parm initializes DECL_INITIAL for non type
template parameters, but TYPE_DECL and TEMPLATE_DECL, stayed with nullptr,
on the other hand as I understood it always initializes TREE_TYPE.
cp/pt.cc::tree process_template_parm:
```
if (parm && TREE_CODE (parm) == TEMPLATE_DECL)
{
t = cxx_make_type (TEMPLATE_TEMPLATE_PARM);
...
TREE_TYPE (result) = t;
...
}
else
{
t = cxx_make_type (TEMPLATE_TYPE_PARM);
/* parm is either IDENTIFIER_NODE or NULL_TREE. */
decl = build_decl (parm_loc,
TYPE_DECL, parm, t);
}
```
In other similar pieces of code the condition is for both for TYPE_DECL and
TEMLATE_DECL:
cp/pt.cc::tree template_parm_to_arg:
```
if (DECL_P (t) && DECL_TEMPLATE_PARM_P (t))
{
if (TREE_CODE (t) == TYPE_DECL
|| TREE_CODE (t) == TEMPLATE_DECL)
t = TREE_TYPE (t);
else
t = DECL_INITIAL (t);
}
```
cp/pt.cc::tree get_template_parm_index:
```
if (TREE_CODE (parm) == PARM_DECL
|| TREE_CODE (parm) == CONST_DECL)
parm = DECL_INITIAL (parm);
else if (TREE_CODE (parm) == TYPE_DECL
|| TREE_CODE (parm) == TEMPLATE_DECL)
parm = TREE_TYPE (parm);
```
Sorry if I ask stupid question.
On Thu, Mar 21, 2024 at 7:28 PM Segher Boessenkool <
segher@xxxxxxxxxxxxxxxxxxx> wrote:
> On Thu, Mar 21, 2024 at 07:12:23PM +0400, Centurion via Gcc-help wrote:
> > HI, I am new in gcc codebase. Can you explain please why we can't just
> use
> > TREE_TYPE(parm) for TEMLATE_TEMPLATE_PARM and why DECL_INITIAL is needed
> > for it? I tried to debug Bug 114377 and it seems to work fine. Thanks
>
> You cannot use TREE_TYPE if that would just access nonsense data.
>
> The wrong thing might still work, in many cases. If you have no
> substantiation why your proposed change would work fine, chances are it
> does not. Sorry.
>
>
> Segher
>
>
> > --- a/gcc/cp/pt.cc
> > +++ b/gcc/cp/pt.cc
> > @@ -11032,10 +11032,7 @@ find_template_parameter_info::found (tree parm)
> > {
> > if (TREE_CODE (parm) == TREE_LIST)
> > parm = TREE_VALUE (parm);
> > - if (TREE_CODE (parm) == TYPE_DECL)
> > - parm = TREE_TYPE (parm);
> > - else
> > - parm = DECL_INITIAL (parm);
> > + parm = TREE_TYPE(parm);
> > gcc_checking_assert (TEMPLATE_PARM_P (parm));
> > return parms.contains (parm);
> > }
>
