move of `loc` in assert.hpp causes clang-tidy error

[braxtons12]

Title says it all, exact output is as below:

This is with clang-tidy 16 and 17

/Users/runner/work/hyperion_assert/hyperion_assert/build/env-cc-release/_deps/flux-src/include/flux/core/assert.hpp:92:71: error: Moved-from object 'loc' of type 'std::source_location' is moved [clang-analyzer-cplusplus.Move,-warnings-as-errors]
            assert_fn{}(idx < limit, "out-of-bounds sequence access", std::move(loc));
                                                                      ^
/Users/runner/work/hyperion_assert/hyperion_assert/src/assert/detail/parser.cpp:156:9: note: Loop condition is true.  Entering loop body
        for(auto cur = flux::first(tokens); !flux::is_last(tokens, cur); flux::inc(tokens, cur)) {
        ^
/Users/runner/work/hyperion_assert/hyperion_assert/src/assert/detail/parser.cpp:157:27: note: Calling 'read_at_fn::operator()'
            auto& token = flux::read_at(tokens, cur);
                          ^~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/runner/work/hyperion_assert/hyperion_assert/build/env-cc-release/_deps/flux-src/include/flux/core/sequence_access.hpp:42:[16](https://github.com/braxtons12/hyperion_assert/actions/runs/8270441336/job/22627969323#step:7:17): note: Calling 'sequence_traits::read_at'
        return traits_t<Seq>::read_at(seq, cur);
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/runner/work/hyperion_assert/hyperion_assert/build/env-cc-release/_deps/flux-src/include/flux/core/default_impls.hpp:193:9: note: Calling 'indexed_bounds_check_fn::operator()'
        indexed_bounds_check(idx, size(self));
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/runner/work/hyperion_assert/hyperion_assert/build/env-cc-release/_deps/flux-src/include/flux/core/assert.hpp:83:13: note: Assuming the condition is true
        if (!std::is_constant_evaluated()) {
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/runner/work/hyperion_assert/hyperion_assert/build/env-cc-release/_deps/flux-src/include/flux/core/assert.hpp:83:9: note: Taking true branch
        if (!std::is_constant_evaluated()) {
        ^
/Users/runner/work/hyperion_assert/hyperion_assert/build/env-cc-release/_deps/flux-src/include/flux/core/assert.hpp:85:43: note: Left side of '&&' is false
            if (__builtin_constant_p(idx) && __builtin_constant_p(limit)) {
                                          ^
/Users/runner/work/hyperion_assert/hyperion_assert/build/env-cc-release/_deps/flux-src/include/flux/core/assert.hpp:91:66: note: Object 'loc' of type 'std::source_location' is left in a valid but unspecified state after move
            assert_fn{}(idx >= T{0}, "index cannot be negative", std::move(loc));
                                                                 ^~~~~~~~~~~~~~
/Users/runner/work/hyperion_assert/hyperion_assert/build/env-cc-release/_deps/flux-src/include/flux/core/assert.hpp:92:25: note: Assuming 'idx' is >= 'limit'
            assert_fn{}(idx < limit, "out-of-bounds sequence access", std::move(loc));
                        ^~~~~~~~~~~
/Users/runner/work/hyperion_assert/hyperion_assert/build/env-cc-release/_deps/flux-src/include/flux/core/assert.hpp:92:71: note: Moved-from object 'loc' of type 'std::source_location' is moved
            assert_fn{}(idx < limit, "out-of-bounds sequence access", std::move(loc));

[braxtons12]

I think the correct thing to do here would be to just not std::move loc in either of those asserts. It's not specified by the standard, but source_location is trivially copyable on all three of the major implementations, and should be on any reasonable implementation as well, in which case moving doesn't actually do anything anyway.

[tcbrindle]

Hi @braxtons12, thanks for the bug report.

The double move is actually pretty obvious in the source code, I'm not sure how I missed it!

https://github.com/tcbrindle/flux/blob/8ae438be0471e46dc7d24077cab37fd209387ccd/include/flux/core/assert.hpp#L91-L92

(As you point out, since source_location is trivially copyable this isn't actually a problem in practice.)

This should be an easy fix :)