Re: [PATCH] c++: address of NTTP object as targ [PR113242]

[Jason Merrill <jason@redhat.com>]

On 1/5/24 11:50, Patrick Palka wrote:
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK
> for trunk and perhaps 13?
> 
> -- >8 --
> 
> invalid_tparm_referent_p was rejecting using the address of a class NTTP
> object as a template argument, but this should be fine.

Hmm, I suppose so; https://eel.is/c++draft/temp#param-8 saying "No two 
template parameter objects are template-argument-equivalent" suggests 
there can be only one.  And clang/msvc allow it.

> 	PR c++/113242
> 
> gcc/cp/ChangeLog:
> 
> 	* pt.cc (invalid_tparm_referent_p) <case ADDR_EXPR>: Suppress
> 	DECL_ARTIFICIAL rejection test for class NTTP objects.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/cpp2a/nontype-class61.C: New test.
> ---
>   gcc/cp/pt.cc                                 |  3 ++-
>   gcc/testsuite/g++.dg/cpp2a/nontype-class61.C | 27 ++++++++++++++++++++
>   2 files changed, 29 insertions(+), 1 deletion(-)
>   create mode 100644 gcc/testsuite/g++.dg/cpp2a/nontype-class61.C
> 
> diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> index 154ac76cb65..8c7d178328d 100644
> --- a/gcc/cp/pt.cc
> +++ b/gcc/cp/pt.cc
> @@ -7219,7 +7219,8 @@ invalid_tparm_referent_p (tree type, tree expr, tsubst_flags_t complain)
>   	   * a string literal (5.13.5),
>   	   * the result of a typeid expression (8.2.8), or
>   	   * a predefined __func__ variable (11.4.1).  */
> -	else if (VAR_P (decl) && DECL_ARTIFICIAL (decl))
> +	else if (VAR_P (decl) && !DECL_NTTP_OBJECT_P (decl)
> +		 && DECL_ARTIFICIAL (decl))

If now some artificial variables are OK and others are not, perhaps we 
should enumerate them either way and abort if it's one we haven't 
specifically considered.

Jason