[PATCH v6 9/8] libstdc++: Uglify __mapping_alike template parameter and fix test and typo in comment.

[Luc Grosheintz]

On 6/5/25 17:18, Tomasz Kamiński wrote:
> When the static assert was generated from instantiations of default member
> initializer of class B, the error was not generated for B<1, std::layout_left,
> std::layout_left> case, only when -D_GLIBCXX_DEBUG was set. Changing B calls to
> functions fixes that.

Thank you for catching and fixing these! I'll include runs with and
without -D_GLIBCXX_DEBUG to the testing routine.

Can one automatically detect non-uglified names? Maybe even just listing
them all would help.

> 
> libstdc++-v3/ChangeLog:
> 
> 	* include/std/mdspan (__mdspan::__mapping_alike): Rename template
> 	parameter from M to _M_p.
> 	(layout_stride::mapping): Fix typo in comment.
> 	* 23_containers/mdspan/layouts/class_mandate_neg.cc: Changed B to
> 	function.
> ---
> This patch add minor fixes suggeted by Daniel. It also reworks a bit
> class_mandate_neg.cc test, as previously one error was not generated
> when debug was enabled.
> 
>   libstdc++-v3/include/std/mdspan                | 18 +++++++++---------
>   .../mdspan/layouts/class_mandate_neg.cc        | 18 ++++++++++--------
>   2 files changed, 19 insertions(+), 17 deletions(-)
> 
> diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan
> index 4a3e863bed5..fbb85fe3f73 100644
> --- a/libstdc++-v3/include/std/mdspan
> +++ b/libstdc++-v3/include/std/mdspan
> @@ -780,16 +780,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>   
>     namespace __mdspan
>     {
> -    template<typename M>
> +    template<typename _Mp>
>         concept __mapping_alike = requires
>         {
> -	requires __is_extents<typename M::extents_type>;
> -	{ M::is_always_strided() } -> same_as<bool>;
> -	{ M::is_always_exhaustive() } -> same_as<bool>;
> -	{ M::is_always_unique() } -> same_as<bool>;
> -	bool_constant<M::is_always_strided()>::value;
> -	bool_constant<M::is_always_exhaustive()>::value;
> -	bool_constant<M::is_always_unique()>::value;
> +	requires __is_extents<typename _Mp::extents_type>;
> +	{ _Mp::is_always_strided() } -> same_as<bool>;
> +	{ _Mp::is_always_exhaustive() } -> same_as<bool>;
> +	{ _Mp::is_always_unique() } -> same_as<bool>;
> +	bool_constant<_Mp::is_always_strided()>::value;
> +	bool_constant<_Mp::is_always_exhaustive()>::value;
> +	bool_constant<_Mp::is_always_unique()>::value;
>         };
>   
>       template<typename _Mapping>
> @@ -847,7 +847,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>         mapping() noexcept
>         {
>   	// The precondition is either statically asserted, or automatically
> -	// satisfied because dynamic extents are zero-initialzied.
> +	// satisfied because dynamic extents are zero-initialized.
>   	size_t __stride = 1;
>   	for (size_t __i = extents_type::rank(); __i > 0; --__i)
>   	  {
> diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc
> index 70a25707cb2..7091153daba 100644
> --- a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc
> +++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc
> @@ -18,7 +18,8 @@ template<typename Layout>
>     };
>   
>   template<size_t Count, typename Layout, typename OLayout>
> -  struct B
> +  bool
> +  B()
>     {
>       using Extents = std::extents<uint8_t, dyn, dyn, Count>;
>       using OExtents = std::extents<uint16_t, n, 4, Count>;
> @@ -27,20 +28,21 @@ template<size_t Count, typename Layout, typename OLayout>
>       using OMapping = typename OLayout::mapping<OExtents>;
>   
>       Mapping m{OMapping{}};
> +    return true;
>     };
>   
>   A<std::layout_left> a_left;                      // { dg-error "required from" }
>   A<std::layout_right> a_right;                    // { dg-error "required from" }
>   A<std::layout_stride> a_stride;                  // { dg-error "required from" }
>   
> -B<1, std::layout_left, std::layout_left> b0;     // { dg-error "required here" }
> -B<2, std::layout_left, std::layout_stride> b1;   // { dg-error "required here" }
> +auto b1 = B<1, std::layout_left, std::layout_left>();     // { dg-error "required from" }
> +auto b2 = B<2, std::layout_left, std::layout_stride>();   // { dg-error "required from" }
>   
> -B<3, std::layout_right, std::layout_right> b2;   // { dg-error "required here" }
> -B<4, std::layout_right, std::layout_stride> b3;  // { dg-error "required here" }
> +auto b3 = B<3, std::layout_right, std::layout_right>();   // { dg-error "required from" }
> +auto b4 = B<4, std::layout_right, std::layout_stride>();  // { dg-error "required from" }
>   
> -B<5, std::layout_stride, std::layout_right> b4;  // { dg-error "required here" }
> -B<6, std::layout_stride, std::layout_left> b5;   // { dg-error "required here" }
> -B<7, std::layout_stride, std::layout_stride> b6; // { dg-error "required here" }
> +auto b5 = B<5, std::layout_stride, std::layout_right>();  // { dg-error "required from" }
> +auto b6 = B<6, std::layout_stride, std::layout_left>();   // { dg-error "required from" }
> +auto b7 = B<7, std::layout_stride, std::layout_stride>(); // { dg-error "required from" }
>   
>   // { dg-prune-output "must be representable as index_type" }