On Tue, 8 Jul 2025 at 09:23, Tomasz Kamiński <tkami...@redhat.com> wrote:
>
> The standard defines separate specializations of range-default-formatter, out
> of which only one for range_format::sequence provide the set_brackets and
> set_separator methods. We implemented it as one specialization and exposed
> this method for range_format other than string or debug_string, i.e. when
> range_formatter was used as underlying formatter.
>
> PR libstdc++/119861
>
> libstdc++-v3/ChangeLog:
>
> * include/std/format (formatter<_Rg, _CharT>::set_separator)
> (formatter<_Rg, _CharT>::set_brackets): Constrain with
> (format_kind<_Rg> == range_format::sequence).
> * testsuite/std/format/ranges/pr119861_neg.cc: New test.
> ---
> Testing on x86_64-linux locally. Format test passed.
> OK for trunk?
OK, thanks
> I do not think this it is necessary to backport this to 15,
> as we were providing functions in more cases that needed. Let me know
> what you think.
I agree it's not very important to backport, but it also seems simple
and safe to do so.
> libstdc++-v3/include/std/format | 4 +-
> .../std/format/ranges/pr119861_neg.cc | 52 +++++++++++++++++++
> 2 files changed, 54 insertions(+), 2 deletions(-)
> create mode 100644 libstdc++-v3/testsuite/std/format/ranges/pr119861_neg.cc
>
> diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
> index 5749aa1995a..d584b81c78a 100644
> --- a/libstdc++-v3/include/std/format
> +++ b/libstdc++-v3/include/std/format
> @@ -6030,13 +6030,13 @@ namespace __format
>
> constexpr void
> set_separator(basic_string_view<_CharT> __sep) noexcept
> - requires (!_S_range_format_is_string)
> + requires (format_kind<_Rg> == range_format::sequence)
> { _M_under.set_separator(__sep); }
>
> constexpr void
> set_brackets(basic_string_view<_CharT> __open,
> basic_string_view<_CharT> __close) noexcept
> - requires (!_S_range_format_is_string)
> + requires (format_kind<_Rg> == range_format::sequence)
> { _M_under.set_brackets(__open, __close); }
>
> // We deviate from standard, that declares this as template accepting
> diff --git a/libstdc++-v3/testsuite/std/format/ranges/pr119861_neg.cc
> b/libstdc++-v3/testsuite/std/format/ranges/pr119861_neg.cc
> new file mode 100644
> index 00000000000..9a6ed16393e
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/std/format/ranges/pr119861_neg.cc
> @@ -0,0 +1,52 @@
> +// { dg-do compile { target c++23 } }
> +
> +#include <format>
> +#include <vector>
> +
> +// only format_kind::sequence provides set_brackets and set_separator methods
> +
> +template<std::range_format fk, typename T>
> +struct MyCont : std::vector<T>
> +{
> + using std::vector<T>::vector;
> +};
> +
> +template<std::range_format fk, typename T>
> +constexpr std::range_format std::format_kind<MyCont<fk, T>> = fk;
> +
> +void test_sequence()
> +{
> + std::formatter<MyCont<std::range_format::sequence, int>, char> fmtter;
> + fmtter.set_brackets("{", "}");
> + fmtter.set_separator(",");
> +}
> +
> +void test_map()
> +{
> + std::formatter<MyCont<std::range_format::map, std::pair<int, int>>, char>
> fmtter;
> + fmtter.set_brackets("{", "}"); // { dg-error "here" }
> + fmtter.set_separator(","); // { dg-error "here" }
> +}
> +
> +void test_set()
> +{
> + std::formatter<MyCont<std::range_format::set, int>, char> fmtter;
> + fmtter.set_brackets("{", "}"); // { dg-error "here" }
> + fmtter.set_separator(","); // { dg-error "here" }
> +}
> +
> +void test_string()
> +{
> + std::formatter<MyCont<std::range_format::string, char>, char> fmtter;
> + fmtter.set_brackets("{", "}"); // { dg-error "here" }
> + fmtter.set_separator(","); // { dg-error "here" }
> +}
> +
> +void test_debug_string()
> +{
> + std::formatter<MyCont<std::range_format::debug_string, char>, char> fmtter;
> + fmtter.set_brackets("{", "}"); // { dg-error "here" }
> + fmtter.set_separator(","); // { dg-error "here" }
> +}
> +
> +// { dg-error "no matching function for call to 'std::formatter<" "" {
> target *-*-* } 0 }
> --
> 2.49.0
>
