[Bug libstdc++/109814] New: freestanding using cmath does not compile anymore

["lestofante88 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109814

            Bug ID: 109814
           Summary: freestanding using cmath does not compile anymore
           Product: gcc
           Version: 13.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: lestofante88 at gmail dot com
  Target Milestone: ---

My code stop compiling after updating from
arm-none-eabi-gcc (Arch Repository) 12.2.0
to
arm-none-eabi-gcc (Arch Repository) 13.1.0
(cant easily test any version in-between)

My understanding is that I am incorrectly using non-freestand library in
freestand mode (cmath in this case).
The problem with this is i am quite sure in embedded a lot of project does. 
This breakage, even if technically correct, may create a lot of issue in
embedded projects and may deserve a special handling, would that be good
communication of the breaking changes, or revert.

REPRODUCE:
- create a file test.cpp containing

#include <cmath>

- compile with 
arm-none-eabi-g++ --freestanding -c test.cpp

RESULT
On gcc 12.2.0: compilation successful
On gcc 13.1.0:

In file included from /usr/arm-none-eabi/include/c++/13.1.0/cmath:41,
                 from test.cpp:1:
/usr/arm-none-eabi/include/c++/13.1.0/bits/requires_hosted.h:34:4: error:
#error "This header is not available in freestanding mode."
   34 | #  error "This header is not available in freestanding mode."
      |    ^~~~~
In file included from /usr/arm-none-eabi/include/c++/13.1.0/bits/specfun.h:47,
                 from /usr/arm-none-eabi/include/c++/13.1.0/cmath:3716:
/usr/arm-none-eabi/include/c++/13.1.0/tr1/gamma.tcc: In function '_Tp
std::__detail::__log_gamma(_Tp)':
/usr/arm-none-eabi/include/c++/13.1.0/tr1/gamma.tcc:236:18: error:
'__throw_domain_error' is not a member of 'std'; did you mean
'__throw_runtime_error'?
  236 |             std::__throw_domain_error(__N("Argument is nonpositive
integer "
      |                  ^~~~~~~~~~~~~~~~~~~~
      |                  __throw_runtime_error

[...] the error repeat for multiple functions.