On Tue, Nov 12, 2019 at 5:54 AM Jason Merrill <ja...@redhat.com> wrote:
>
> I'm not sure what semantics we might eventually want for vector <=>, but let's
> give a sorry for now.
Given our vector extension does elementwise comparisons I don't think we can
implement <=> in a reasonable manner. What we could eventually do is
specify that <=> works on the whole vector, but then only unordered compares
are easy to define there...
So I think an error is more appropriate here, sorry indicates that
we're just not
implementing it.
Richard.
> Tested x86_64-pc-linux-gnu, applying to trunk.
>
> ---
> gcc/cp/typeck.c | 7 +++++++
> gcc/testsuite/g++.dg/cpp2a/spaceship-vec1.C | 11 +++++++++++
> 2 files changed, 18 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/spaceship-vec1.C
>
> diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
> index 124d16a31fb..ff603f3d8d9 100644
> --- a/gcc/cp/typeck.c
> +++ b/gcc/cp/typeck.c
> @@ -5224,6 +5224,13 @@ cp_build_binary_op (const op_location_t &location,
> "types %qT and %qT", type0, type1);
> }
>
> + if (resultcode == SPACESHIP_EXPR)
> + {
> + if (complain & tf_error)
> + sorry_at (location, "three-way comparison of vectors");
> + return error_mark_node;
> + }
> +
> /* Always construct signed integer vector type. */
> intt = c_common_type_for_size
> (GET_MODE_BITSIZE (SCALAR_TYPE_MODE (TREE_TYPE (type0))), 0);
> diff --git a/gcc/testsuite/g++.dg/cpp2a/spaceship-vec1.C
> b/gcc/testsuite/g++.dg/cpp2a/spaceship-vec1.C
> new file mode 100644
> index 00000000000..83547691118
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/spaceship-vec1.C
> @@ -0,0 +1,11 @@
> +// { dg-do compile { target c++2a } }
> +
> +#include <compare>
> +
> +#define vector __attribute__((vector_size(4*sizeof(int)) ))
> +
> +int main()
> +{
> + vector int a, b;
> + a <=> b; // { dg-message "three-way comparison of vector"
> }
> +}
>
> base-commit: f15dc29a9734e360497f5bb40be6b25dcbc11645
> --
> 2.18.1
>
