On Tue, Mar 10, 2026 at 07:51:53AM +0100, Jakub Jelinek wrote:
> Hi!
> 
> The following testcases FAIL (annotations12.C is directly from
> https://eel.is/c++draft/meta.reflection#annotation-4 ) because it is
> called on a reflection of class template instantiation which has been
> just looked up but not yet completed, and in that case it doesn't
> have any attributes instantiated.
> Only complete_type instantiates those.  Unlike the second argument
> of annotations_of_with_type where the standard requires is_complete_type,
> in this case it doesn't, so it is fine if one uses
> struct S;
> static_assert (annotations_of (^^S).size () == 0);
> but I'm afraid we need to instantiate the argument to get the annotations.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

This patch also fixes constant_of5.C (except line 84), which is awesome.
Please also adjust that test.  Otherwise looks good to me, thanks.

> 2026-03-10  Jakub Jelinek  <[email protected]>
> 
>       PR c++/124399
>       * reflect.cc (eval_annotations_of): Call complete_type on r if it
>       is a type.
> 
>       * g++.dg/reflect/annotations3.C: Uncomment 3 test lines.
>       * g++.dg/reflect/annotations12.C: New test.
>       * g++.dg/reflect/constant_of6.C: Remove dg-error directive.
>       * g++.dg/reflect/extract6.C: Remove 2 dg-error directives.
> 
> --- gcc/cp/reflect.cc.jj      2026-03-06 14:25:25.978299299 +0100
> +++ gcc/cp/reflect.cc 2026-03-09 11:04:26.056073667 +0100
> @@ -3800,6 +3800,7 @@ eval_annotations_of (location_t loc, con
>      }
>    else if (TYPE_P (r))
>      {
> +      complete_type (r);
>        if (typedef_variant_p (r))
>       r = DECL_ATTRIBUTES (TYPE_NAME (r));
>        else
> --- gcc/testsuite/g++.dg/reflect/annotations3.C.jj    2026-01-15 
> 16:33:47.004726583 +0100
> +++ gcc/testsuite/g++.dg/reflect/annotations3.C       2026-03-09 
> 11:05:35.695889229 +0100
> @@ -41,9 +41,9 @@ static_assert (type_of (a0) == ^^int);
>  template <class T>
>  struct [[=42]] D {};
>  
> -//constexpr std::meta::info a1 = annotations_of (^^D<int>)[0];
> -//constexpr std::meta::info a2 = annotations_of (^^D<char>)[0];
> -//static_assert (is_annotation (a1) && is_annotation (a2));
> +constexpr std::meta::info a1 = annotations_of (^^D<int>)[0];
> +constexpr std::meta::info a2 = annotations_of (^^D<char>)[0];
> +static_assert (is_annotation (a1) && is_annotation (a2));
>  
>  [[=1, =2L, =3.0, =4U, =5U, =6L, =7U]] int y;
>  static_assert (annotations_of (^^y).size () == 7);
> --- gcc/testsuite/g++.dg/reflect/annotations12.C.jj   2026-03-09 
> 11:05:49.720650693 +0100
> +++ gcc/testsuite/g++.dg/reflect/annotations12.C      2026-03-09 
> 11:16:59.402260389 +0100
> @@ -0,0 +1,13 @@
> +// PR c++/124399
> +// { dg-do compile { target c++26 } }
> +// { dg-options "-freflection" }
> +
> +#include <meta>
> +
> +template <class T>
> +  struct [[=42]] D { };
> +
> +constexpr std::meta::info a1 = annotations_of (^^D <int>)[0];
> +constexpr std::meta::info a2 = annotations_of (^^D <char>)[0];
> +static_assert (a1 != a2);
> +static_assert (constant_of (a1) == constant_of (a2));
> --- gcc/testsuite/g++.dg/reflect/constant_of6.C.jj    2026-01-15 
> 16:33:47.005097993 +0100
> +++ gcc/testsuite/g++.dg/reflect/constant_of6.C       2026-03-09 
> 11:15:52.006406700 +0100
> @@ -17,4 +17,3 @@ struct [[=[:constant_of (annotations_of
>  
>  constexpr auto y = constant_of (annotations_of (^^bar<^^::fn>)[0]);
>  constexpr auto z = constant_of (annotations_of (^^Y<^^::S>)[0]);
> -// { dg-error "call to non-.constexpr." "" { target *-*-* } 0 }
> --- gcc/testsuite/g++.dg/reflect/extract6.C.jj        2026-01-15 
> 16:33:47.008097942 +0100
> +++ gcc/testsuite/g++.dg/reflect/extract6.C   2026-03-09 11:16:33.271704833 
> +0100
> @@ -15,6 +15,5 @@ template<info R>
>  struct [[=[:constant_of (annotations_of (R)[0]):]]] TCls {};
>  
>  static_assert (extract<int>(annotations_of (^^TFn<^^::fn>)[0]) == 1);
> -static_assert (extract<int>(annotations_of (^^TCls<^^::S>)[0]) == 3); // { 
> dg-error "non-constant" }
> +static_assert (extract<int>(annotations_of (^^TCls<^^::S>)[0]) == 3);
>  static_assert (extract<int>(annotations_of (^^fn)[0]) == 1);
> -// { dg-error "call to non-.constexpr." "" { target *-*-* } 0 }
> 
>       Jakub
> 

Marek

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