Syntax error in type_traits

[Jesper Dybdal <jd-debian-user@dybdal.dk>]

There is a syntax error (an erroneous ">" character) in
    /usr/include/c++/12/type_traits
in Bookworm.   So compiling any program that includes the <string> 
header fails:

echo "#include <string>" >error.cpp
g++ -c error.cpp

Results in:

> In file included from /usr/include/c++/12/bits/char_traits.h:42,
>                  from /usr/include/c++/12/string:40,
>                  from error.cpp:1:
> /usr/include/c++/12/type_traits:2614:11: error: expected identifier 
> before ‘>’ token
>  2614 |     using >enable_if_t = typename enable_if<_Cond, _Tp>::type;
>       |           ^
> /usr/include/c++/12/type_traits:2614:11: error: expected 
> unqualified-id before ‘>’ token
> In file included from /usr/include/c++/12/bits/refwrap.h:38,
>                  from /usr/include/c++/12/string:51:
> /usr/include/c++/12/bits/invoke.h:103:15: error: ‘enable_if_t’ does 
> not name a type; did you mean ‘enable_if’?
>   103 |     constexpr enable_if_t<is_invocable_r_v<_Res, _Callable, 
> _Args...>, _Res>

and a lot of other error messages (quoted in full below).

It compiles wiithout problems with -std=c++11.
It also compiles without problems if the strange ">" (in "using 
>enable_if_t = ") is removed.

Could someone familiar with the correct way of reporting such things 
please report this?
Versions:
> jd@nuser:~$ cat /etc/debian_version
> 12.9
> jd@nuser:~$ g++ --version
> g++ (Debian 12.2.0-14) 12.2.0
>
> jd@nuser:~$ ldd --version
> ldd (Debian GLIBC 2.36-9+deb12u9) 2.36

The full set of error messages is:

> In file included from /usr/include/c++/12/bits/char_traits.h:42,
>                  from /usr/include/c++/12/string:40,
>                  from error.cpp:1:
> /usr/include/c++/12/type_traits:2614:11: error: expected identifier 
> before ‘>’ token
>  2614 |     using >enable_if_t = typename enable_if<_Cond, _Tp>::type;
>       |           ^
> /usr/include/c++/12/type_traits:2614:11: error: expected 
> unqualified-id before ‘>’ token
> In file included from /usr/include/c++/12/bits/refwrap.h:38,
>                  from /usr/include/c++/12/string:51:
> /usr/include/c++/12/bits/invoke.h:103:15: error: ‘enable_if_t’ does 
> not name a type; did you mean ‘enable_if’?
>   103 |     constexpr enable_if_t<is_invocable_r_v<_Res, _Callable, 
> _Args...>, _Res>
>       |               ^~~~~~~~~~~
>       |               enable_if
> In file included from /usr/include/c++/12/string:53:
> /usr/include/c++/12/bits/basic_string.h:155:24: error: ‘enable_if_t’ 
> does not name a type; did you mean ‘enable_if’?
>   155 |         using _If_sv = enable_if_t<
>       |                        ^~~~~~~~~~~
>       |                        enable_if
> /usr/include/c++/12/bits/basic_string.h:772:27: error: ‘enable_if_t’ 
> does not name a type; did you mean ‘enable_if’?
>   772 |                typename = enable_if_t<is_convertible_v<const 
> _Tp&, __sv_type>>>
>       |                           ^~~~~~~~~~~
>       |                           enable_if
> /usr/include/c++/12/bits/basic_string.h:772:38: error: expected ‘>’ 
> before ‘<’ token
>   772 |                typename = enable_if_t<is_convertible_v<const 
> _Tp&, __sv_type>>>
>       |                                      ^
> /usr/include/c++/12/bits/basic_string.h:783:41: error: ‘_If_sv’ does 
> not name a type
>   783 |       template<typename _Tp, typename = _If_sv<_Tp, void>>
>       |                                         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:783:47: error: expected ‘>’ 
> before ‘<’ token
>   783 |       template<typename _Tp, typename = _If_sv<_Tp, void>>
>       |                                               ^
> /usr/include/c++/12/bits/basic_string.h:927:8: error: ‘_If_sv’ does 
> not name a type
>   927 |        _If_sv<_Tp, basic_string&>
>       |        ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:1375:9: error: ‘_If_sv’ does 
> not name a type
>  1375 |         _If_sv<_Tp, basic_string&>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:1492:9: error: ‘_If_sv’ does 
> not name a type
>  1492 |         _If_sv<_Tp, basic_string&>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:1508:9: error: ‘_If_sv’ does 
> not name a type
>  1508 |         _If_sv<_Tp, basic_string&>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:1704:9: error: ‘_If_sv’ does 
> not name a type
>  1704 |         _If_sv<_Tp, basic_string&>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:1720:9: error: ‘_If_sv’ does 
> not name a type
>  1720 |         _If_sv<_Tp, basic_string&>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:1986:9: error: ‘_If_sv’ does 
> not name a type
>  1986 |         _If_sv<_Tp, basic_string&>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:2003:9: error: ‘_If_sv’ does 
> not name a type
>  2003 |         _If_sv<_Tp, basic_string&>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:2439:9: error: ‘_If_sv’ does 
> not name a type
>  2439 |         _If_sv<_Tp, basic_string&>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:2457:9: error: ‘_If_sv’ does 
> not name a type
>  2457 |         _If_sv<_Tp, basic_string&>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:2479:9: error: ‘_If_sv’ does 
> not name a type
>  2479 |         _If_sv<_Tp, basic_string&>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:2633:9: error: ‘_If_sv’ does 
> not name a type
>  2633 |         _If_sv<_Tp, size_type>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:2699:9: error: ‘_If_sv’ does 
> not name a type
>  2699 |         _If_sv<_Tp, size_type>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:2784:9: error: ‘_If_sv’ does 
> not name a type
>  2784 |         _If_sv<_Tp, size_type>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:2873:9: error: ‘_If_sv’ does 
> not name a type
>  2873 |         _If_sv<_Tp, size_type>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:2960:9: error: ‘_If_sv’ does 
> not name a type
>  2960 |         _If_sv<_Tp, size_type>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:3048:9: error: ‘_If_sv’ does 
> not name a type
>  3048 |         _If_sv<_Tp, size_type>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:3162:9: error: ‘_If_sv’ does 
> not name a type
>  3162 |         _If_sv<_Tp, int>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:3187:9: error: ‘_If_sv’ does 
> not name a type
>  3187 |         _If_sv<_Tp, int>
>       |         ^~~~~~
> /usr/include/c++/12/bits/basic_string.h:3207:9: error: ‘_If_sv’ does 
> not name a type
>  3207 |         _If_sv<_Tp, int>
>       |         ^~~~~~

Thanks,
Jesper

--
Jesper Dybdal
https://www.dybdal.dk