Re: [PATCH] c++: disallow constinit on functions [PR111173]

[Jason Merrill <jason@redhat.com>]

On 8/29/23 15:01, Marek Polacek wrote:
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

OK.

> -- >8 --
> 
> [dcl.constinit]/1: The constinit specifier shall be applied only to a declaration
> of a variable with static or thread storage duration.
> 
> and while we detect
> 
>    constinit int fn();
> 
> we weren't detecting
> 
>    using F = int();
>    constinit F f;
> 
> 	PR c++/111173
> 
> gcc/cp/ChangeLog:
> 
> 	* decl.cc (grokdeclarator): Disallow constinit on functions.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/cpp2a/constinit19.C: New test.
> ---
>   gcc/cp/decl.cc                           | 3 +++
>   gcc/testsuite/g++.dg/cpp2a/constinit19.C | 5 +++++
>   2 files changed, 8 insertions(+)
>   create mode 100644 gcc/testsuite/g++.dg/cpp2a/constinit19.C
> 
> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
> index bea0ee92106..a0e8a24efc0 100644
> --- a/gcc/cp/decl.cc
> +++ b/gcc/cp/decl.cc
> @@ -14639,6 +14639,9 @@ grokdeclarator (const cp_declarator *declarator,
>   			"storage class %<thread_local%> invalid for "
>   			"function %qs", name);
>   	  }
> +	else if (constinit_p)
> +	  error_at (declspecs->locations[ds_constinit],
> +		    "%<constinit%> specifier invalid for function %qs", name);
>   
>           if (virt_specifiers)
>             error ("virt-specifiers in %qs not allowed outside a class "
> diff --git a/gcc/testsuite/g++.dg/cpp2a/constinit19.C b/gcc/testsuite/g++.dg/cpp2a/constinit19.C
> new file mode 100644
> index 00000000000..5be610a18a2
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/constinit19.C
> @@ -0,0 +1,5 @@
> +// PR c++/111173
> +// { dg-do compile { target c++20 } }
> +
> +using Function = int();
> +constinit Function f; // { dg-error ".constinit. specifier invalid for function" }
> 
> base-commit: fce74ce2535aa3b7648ba82e7e61eb77d0175546