Re: [PATCH] c++: Add !TYPE_P assert to type_dependent_expression_p [PR99080]

[Jason Merrill <jason@redhat.com>]

On 5/26/22 20:33, Marek Polacek wrote:
> As discussed here:
> <https://gcc.gnu.org/pipermail/gcc-patches/2021-February/564629.html>,
> type_dependent_expression_p should not be called with a type argument.
> 
> I promised I'd add an assert so here it is.  One place needed adjusting,
> the comment explains why.
> 
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> 
> 	PR c++/99080
> 
> gcc/cp/ChangeLog:
> 
> 	* pt.cc (type_dependent_expression_p): Assert !TYPE_P.
> 	* semantics.cc (finish_id_expression_1): Don't call
> 	type_dependent_expression_p for a type.
> ---
>   gcc/cp/pt.cc        | 2 ++
>   gcc/cp/semantics.cc | 4 +++-
>   2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> index 24bbe2f4060..89156cb88b4 100644
> --- a/gcc/cp/pt.cc
> +++ b/gcc/cp/pt.cc
> @@ -27727,6 +27727,8 @@ type_dependent_expression_p (tree expression)
>     if (expression == NULL_TREE || expression == error_mark_node)
>       return false;
>   
> +  gcc_checking_assert (!TYPE_P (expression));
> +
>     STRIP_ANY_LOCATION_WRAPPER (expression);
>   
>     /* An unresolved name is always dependent.  */
> diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> index cd7a2818feb..7f8502f49b0 100644
> --- a/gcc/cp/semantics.cc
> +++ b/gcc/cp/semantics.cc
> @@ -4141,7 +4141,9 @@ finish_id_expression_1 (tree id_expression,
>       }
>     else
>       {
> -      bool dependent_p = type_dependent_expression_p (decl);
> +      /* DECL could be e.g. UNBOUND_CLASS_TEMPLATE which is a type which
> +	 t_d_e_p doesn't accept.  */
> +      bool dependent_p = !TYPE_P (decl) && type_dependent_expression_p (decl);

Maybe instead we could handle UNBOUND_CLASS_TEMPLATE at a higher level 
in the function, like with an 'else if' before this 'else'?

>         /* If the declaration was explicitly qualified indicate
>   	 that.  The semantics of `A::f(3)' are different than
> 
> base-commit: 367740bf6d3a6627798b3955e5d85efc7549ef50