`bugprone-exception-escape.FunctionsThatShouldNotThrow` should consider `iter_move` and `iter_swap`

[cjdb]

These are the (moral) equivalent of *std::move(i) and swap(*i, *j), and shouldn't throw either.

[llvmbot]

Hi!

This issue may be a good introductory issue for people new to working on LLVM. If you would like to work on this issue, your first steps are:

1. In the comments of the issue, request for it to be assigned to you.
2. Fix the issue locally.
3. Run the test suite locally. Remember that the subdirectories under test/ create fine-grained testing targets, so you can e.g. use make check-clang-ast to only run Clang's AST tests.
4. Create a Git commit.
5. Run git clang-format HEAD~1 to format your changes.
6. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation.

If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Christopher Di Bella (cjdb)

These are the (moral) equivalent of `*std::move(i)` and `swap(*i, *j)`, and shouldn't throw either.

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: Christopher Di Bella (cjdb)

These are the (moral) equivalent of `*std::move(i)` and `swap(*i, *j)`, and shouldn't throw either.

[da-viper]

@cjdb could you assign this to me ?

[bluescarni]

These are the (moral) equivalent of *std::move(i) and swap(*i, *j), and shouldn't throw either.

@cjdb after upgrading to clang-tidy 21, I see bugprone-exception-escape checks failing in C++20 ranges pipelines with std::views::transform whenever the transformation function object may throw. For reference:

/home/yardbird/miniforge3/envs/mizuba/bin/../lib/gcc/x86_64-conda-linux-gnu/15.1.0/../../../gcc/x86_64-conda-linux-gnu/15.1.0/include/c++/ranges:2109:4: error: an exception may be thrown in function 'iter_move' which should not throw exceptions [bugprone-exception-escape,-warnings-as-errors]
 2109 |           iter_move(const _Iterator& __i) noexcept(noexcept(*__i))
      |           ^
/home/yardbird/repos/mizuba/mizuba/detail/dfloat_utils.hpp:59:9: note: frame #0: unhandled exception of type 'std::overflow_error' may be thrown in function 'checked_dl_add<heyoka::detail::dfloat<double>, double>' here
   59 |         throw std::overflow_error("Overflow detected in a double-length addition");
      |         ^
/home/yardbird/repos/mizuba/mizuba/conjunctions_report_cross_detect_conjunctions_broad_phase.cpp:79:67: note: frame #1: function 'operator()<double>' calls function 'checked_dl_add<heyoka::detail::dfloat<double>, double>' here
   79 |           | std::views::transform([epoch1](const auto t) { return checked_dl_add(epoch1, t); });
      |                                                                   ^
/home/yardbird/miniforge3/envs/mizuba/bin/../lib/gcc/x86_64-conda-linux-gnu/15.1.0/../../../gcc/x86_64-conda-linux-gnu/15.1.0/include/c++/bits/invoke.h:63:14: note: frame #2: function '__invoke_impl<heyoka::detail::dfloat<double>, (lambda at /home/yardbird/repos/mizuba/mizuba/conjunctions_report_cross_detect_conjunctions_broad_phase.cpp:79:35) &, const double &>' calls function 'operator()<double>' here
   63 |     { return std::forward<_Fn>(__f)(std::forward<_Args>(__args)...); }
      |              ^
/home/yardbird/miniforge3/envs/mizuba/bin/../lib/gcc/x86_64-conda-linux-gnu/15.1.0/../../../gcc/x86_64-conda-linux-gnu/15.1.0/include/c++/bits/invoke.h:98:14: note: frame #3: function '__invoke<(lambda at /home/yardbird/repos/mizuba/mizuba/conjunctions_report_cross_detect_conjunctions_broad_phase.cpp:79:35) &, const double &>' calls function '__invoke_impl<heyoka::detail::dfloat<double>, (lambda at /home/yardbird/repos/mizuba/mizuba/conjunctions_report_cross_detect_conjunctions_broad_phase.cpp:79:35) &, const double &>' here
   98 |       return std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
      |              ^
/home/yardbird/miniforge3/envs/mizuba/bin/../lib/gcc/x86_64-conda-linux-gnu/15.1.0/../../../gcc/x86_64-conda-linux-gnu/15.1.0/include/c++/ranges:1998:13: note: frame #4: function 'operator*' calls function '__invoke<(lambda at /home/yardbird/repos/mizuba/mizuba/conjunctions_report_cross_detect_conjunctions_broad_phase.cpp:79:35) &, const double &>' here
 1998 |           { return std::__invoke(*_M_parent->_M_fun, *_M_current); }
      |                    ^
/home/yardbird/miniforge3/envs/mizuba/bin/../lib/gcc/x86_64-conda-linux-gnu/15.1.0/../../../gcc/x86_64-conda-linux-gnu/15.1.0/include/c++/ranges:2114:15: note: frame #5: function 'iter_move' calls function 'operator*' here
 2114 |               return *__i;

This is a bit hard to suppress because the offending code is within the stdlib...