Failing to compiler from master head

[madwax]

Issue

build of master failed.
I have just setup a Ubuntu 24.04 machine, cloned master (9857dcf) and tried to build using cmake as outline in the instructions.

I get the following errors:

In file included from /home/madwax/devel/tmp/osrm-backend/include/extractor/scripting_environment_lua.hpp:15,
from /home/madwax/devel/tmp/osrm-backend/src/extractor/scripting_environment_lua.cpp:1:
In member function ‘void sol::stack::field_getter<T, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[23]; T = char [23]; bool global = false; bool raw = false; = void]’,
inlined from ‘void sol::stack::get_field(lua_State*, Key&&, int) [with bool global = false; bool raw = false; Key = const char (&)[23]]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:12092:62,
inlined from ‘sol::stack::probe sol::stack::probe_field_getter<T, P, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[23]; T = char [23]; P = int; bool b = false; bool raw = false; = void]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16329:21,
inlined from ‘sol::stack::probe sol::stack::probe_field_getter<T, P, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[15]; T = char [15]; P = int; bool b = false; bool raw = false; = void]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16323:9,
inlined from ‘sol::stack::probe sol::stack::probe_get_field(lua_State*, Key&&, int) [with bool global = false; bool raw = false; C = int; Key = const char (&)[15]]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:12112:78,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get_deep_optional(int&, int, Key&&, Keys&& ...) const [with bool global = false; bool raw = false; sol::detail::insert_mode mode = sol::detail::none; T = sol::optional; Key = const char (&)[15]; Keys = {}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25627:62,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get_single(int, Keys&& ...) const [with bool raw = false; Ret = sol::optional; Keys = {const char (&)[15]}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25533:83,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get(Keys&& ...) const [with T = sol::optional; Keys = {const char (&)[15]}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25860:40,
inlined from ‘decltype(auto) sol::table_proxy< , >::tuple_get(std::index_sequence<_Ind ...>) const & [with T = sol::optional; long unsigned int ...I = {0}; Table = sol::basic_table_core<false, sol::basic_reference >&; Key = std::tuple<const char (&)[15]>]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:24742:39,
inlined from ‘decltype(auto) sol::table_proxy< , >::get() const & [with T = sol::optional; Table = sol::basic_table_core<false, sol::basic_reference >&; Key = std::tuple<const char (&)[15]>]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:24847:23,
inlined from ‘sol::proxy_base< >::operator T() const [with T = sol::optional; typename std::enable_if<sol::meta::all<std::integral_constant<bool, (! std::integral_constant<bool, ((((((is_string_literal_array_of_v<T, char> || is_same_v<T, const char*>) || is_same_v<T, char>) || is_string_of_v<T, char>) || is_same_v<T, std::initializer_list >) || is_string_view_of_v<T, char>) || is_null_pointer_v)>::value)>, sol::is_proxy_primitive<typename std::remove_cv<typename std::remove_reference<Iter>::type>::type> >::value, sol::meta::enable_t>::type = sol::meta::enable_t::; Super = sol::table_proxy<sol::basic_table_core<false, sol::basic_reference >&, std::tuple<const char (&)[15]> >]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16973:32,
inlined from ‘osrm::extractor::Sol2ScriptingEnvironment::InitContext(osrm::extractor::LuaScriptingContext&)::<lambda()>’ at /home/madwax/devel/tmp/osrm-backend/src/extractor/scripting_environment_lua.cpp:644:85:
/home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16152:49: error: array subscript ‘const char [23][0]’ is partly outside array bounds of ‘const char [15]’ [-Werror=array-bounds=]
16152 | lua_getfield(L, tableindex, &key[0]);
| ^~~~~~~~~~~~
In member function ‘void sol::stack::field_getter<T, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[30]; T = char [30]; bool global = false; bool raw = false; = void]’,
inlined from ‘void sol::stack::get_field(lua_State*, Key&&, int) [with bool global = false; bool raw = false; Key = const char (&)[30]]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:12092:62,
inlined from ‘sol::stack::probe sol::stack::probe_field_getter<T, P, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[30]; T = char [30]; P = bool; bool b = false; bool raw = false; = void]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16329:21,
inlined from ‘sol::stack::probe sol::stack::probe_field_getter<T, P, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[18]; T = char [18]; P = bool; bool b = false; bool raw = false; = void]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16323:9,
inlined from ‘sol::stack::probe sol::stack::probe_get_field(lua_State*, Key&&, int) [with bool global = false; bool raw = false; C = bool; Key = const char (&)[18]]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:12112:78,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get_deep_optional(int&, int, Key&&, Keys&& ...) const [with bool global = false; bool raw = false; sol::detail::insert_mode mode = sol::detail::none; T = sol::optional; Key = const char (&)[18]; Keys = {}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25627:62,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get_single(int, Keys&& ...) const [with bool raw = false; Ret = sol::optional; Keys = {const char (&)[18]}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25533:83,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get(Keys&& ...) const [with T = sol::optional; Keys = {const char (&)[18]}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25860:40,
inlined from ‘decltype(auto) sol::table_proxy< , >::tuple_get(std::index_sequence<_Ind ...>) const & [with T = sol::optional; long unsigned int ...I = {0}; Table = sol::basic_table_core<false, sol::basic_reference >&; Key = std::tuple<const char (&)[18]>]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:24742:39,
inlined from ‘decltype(auto) sol::table_proxy< , >::get() const & [with T = sol::optional; Table = sol::basic_table_core<false, sol::basic_reference >&; Key = std::tuple<const char (&)[18]>]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:24847:23,
inlined from ‘sol::proxy_base< >::operator T() const [with T = sol::optional; typename std::enable_if<sol::meta::all<std::integral_constant<bool, (! std::integral_constant<bool, ((((((is_string_literal_array_of_v<T, char> || is_same_v<T, const char*>) || is_same_v<T, char>) || is_string_of_v<T, char>) || is_same_v<T, std::initializer_list >) || is_string_view_of_v<T, char>) || is_null_pointer_v)>::value)>, sol::is_proxy_primitive<typename std::remove_cv<typename std::remove_reference<Iter>::type>::type> >::value, sol::meta::enable_t>::type = sol::meta::enable_t::; Super = sol::table_proxy<sol::basic_table_core<false, sol::basic_reference >&, std::tuple<const char (&)[18]> >]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16973:32,
inlined from ‘osrm::extractor::Sol2ScriptingEnvironment::InitContext(osrm::extractor::LuaScriptingContext&)::<lambda()>’ at /home/madwax/devel/tmp/osrm-backend/src/extractor/scripting_environment_lua.cpp:663:83:
/home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16152:49: error: array subscript ‘const char [30][0]’ is partly outside array bounds of ‘const char [18]’ [-Werror=array-bounds=]
16152 | lua_getfield(L, tableindex, &key[0]);
| ^~~~~~~~~~~~
In member function ‘void sol::stack::field_getter<T, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[23]; T = char [23]; bool global = false; bool raw = false; = void]’,
inlined from ‘void sol::stack::get_field(lua_State*, Key&&, int) [with bool global = false; bool raw = false; Key = const char (&)[23]]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:12092:62,
inlined from ‘sol::stack::probe sol::stack::probe_field_getter<T, P, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[23]; T = char [23]; P = int; bool b = false; bool raw = false; = void]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16329:21,
inlined from ‘sol::stack::probe sol::stack::probe_field_getter<T, P, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[17]; T = char [17]; P = unsigned int; bool b = false; bool raw = false; = void]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16323:9,
inlined from ‘sol::stack::probe sol::stack::probe_get_field(lua_State*, Key&&, int) [with bool global = false; bool raw = false; C = unsigned int; Key = const char (&)[17]]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:12112:78,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get_deep_optional(int&, int, Key&&, Keys&& ...) const [with bool global = false; bool raw = false; sol::detail::insert_mode mode = sol::detail::none; T = sol::optional; Key = const char (&)[17]; Keys = {}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25627:62,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get_single(int, Keys&& ...) const [with bool raw = false; Ret = sol::optional; Keys = {const char (&)[17]}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25533:83,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get(Keys&& ...) const [with T = sol::optional; Keys = {const char (&)[17]}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25860:40,
inlined from ‘decltype(auto) sol::table_proxy< , >::tuple_get(std::index_sequence<_Ind ...>) const & [with T = sol::optional; long unsigned int ...I = {0}; Table = sol::basic_table_core<false, sol::basic_reference >&; Key = std::tuple<const char (&)[17]>]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:24742:39,
inlined from ‘decltype(auto) sol::table_proxy< , >::get() const & [with T = sol::optional; Table = sol::basic_table_core<false, sol::basic_reference >&; Key = std::tuple<const char (&)[17]>]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:24847:23,
inlined from ‘sol::proxy_base< >::operator T() const [with T = sol::optional; typename std::enable_if<sol::meta::all<std::integral_constant<bool, (! std::integral_constant<bool, ((((((is_string_literal_array_of_v<T, char> || is_same_v<T, const char*>) || is_same_v<T, char>) || is_string_of_v<T, char>) || is_same_v<T, std::initializer_list >) || is_string_view_of_v<T, char>) || is_null_pointer_v)>::value)>, sol::is_proxy_primitive<typename std::remove_cv<typename std::remove_reference<Iter>::type>::type> >::value, sol::meta::enable_t>::type = sol::meta::enable_t::; Super = sol::table_proxy<sol::basic_table_core<false, sol::basic_reference >&, std::tuple<const char (&)[17]> >]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16973:32,
inlined from ‘osrm::extractor::Sol2ScriptingEnvironment::InitContext(osrm::extractor::LuaScriptingContext&)::<lambda()>’ at /home/madwax/devel/tmp/osrm-backend/src/extractor/scripting_environment_lua.cpp:667:85:
/home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16152:49: error: array subscript ‘const char [23][0]’ is partly outside array bounds of ‘const char [17]’ [-Werror=array-bounds=]
16152 | lua_getfield(L, tableindex, &key[0]);
| ^~~~~~~~~~~~
In member function ‘void sol::stack::field_getter<T, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[30]; T = char [30]; bool global = false; bool raw = false; = void]’,
inlined from ‘void sol::stack::get_field(lua_State*, Key&&, int) [with bool global = false; bool raw = false; Key = const char (&)[30]]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:12092:62,
inlined from ‘sol::stack::probe sol::stack::probe_field_getter<T, P, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[30]; T = char [30]; P = bool; bool b = false; bool raw = false; = void]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16329:21,
inlined from ‘sol::stack::probe sol::stack::probe_field_getter<T, P, global, raw, >::get(lua_State*, Key&&, int) [with Key = const char (&)[18]; T = char [18]; P = bool; bool b = false; bool raw = false; = void]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16323:9,
inlined from ‘sol::stack::probe sol::stack::probe_get_field(lua_State*, Key&&, int) [with bool global = false; bool raw = false; C = bool; Key = const char (&)[18]]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:12112:78,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get_deep_optional(int&, int, Key&&, Keys&& ...) const [with bool global = false; bool raw = false; sol::detail::insert_mode mode = sol::detail::none; T = sol::optional; Key = const char (&)[18]; Keys = {}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25627:62,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get_single(int, Keys&& ...) const [with bool raw = false; Ret = sol::optional; Keys = {const char (&)[18]}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25533:83,
inlined from ‘decltype(auto) sol::basic_table_core<, >::traverse_get(Keys&& ...) const [with T = sol::optional; Keys = {const char (&)[18]}; bool top_level = false; ref_t = sol::basic_reference]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:25860:40,
inlined from ‘decltype(auto) sol::table_proxy< , >::tuple_get(std::index_sequence<_Ind ...>) const & [with T = sol::optional; long unsigned int ...I = {0}; Table = sol::basic_table_core<false, sol::basic_reference >&; Key = std::tuple<const char (&)[18]>]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:24742:39,
inlined from ‘decltype(auto) sol::table_proxy< , >::get() const & [with T = sol::optional; Table = sol::basic_table_core<false, sol::basic_reference >&; Key = std::tuple<const char (&)[18]>]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:24847:23,
inlined from ‘sol::proxy_base< >::operator T() const [with T = sol::optional; typename std::enable_if<sol::meta::all<std::integral_constant<bool, (! std::integral_constant<bool, ((((((is_string_literal_array_of_v<T, char> || is_same_v<T, const char*>) || is_same_v<T, char>) || is_string_of_v<T, char>) || is_same_v<T, std::initializer_list >) || is_string_view_of_v<T, char>) || is_null_pointer_v)>::value)>, sol::is_proxy_primitive<typename std::remove_cv<typename std::remove_reference<Iter>::type>::type> >::value, sol::meta::enable_t>::type = sol::meta::enable_t::; Super = sol::table_proxy<sol::basic_table_core<false, sol::basic_reference >&, std::tuple<const char (&)[18]> >]’ at /home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16973:32,
inlined from ‘osrm::extractor::Sol2ScriptingEnvironment::InitContext(osrm::extractor::LuaScriptingContext&)::<lambda()>’ at /home/madwax/devel/tmp/osrm-backend/src/extractor/scripting_environment_lua.cpp:671:83:
/home/madwax/devel/tmp/osrm-backend/third_party/sol2/include/sol/sol.hpp:16152:49: error: array subscript ‘const char [30][0]’ is partly outside array bounds of ‘const char [18]’ [-Werror=array-bounds=]
16152 | lua_getfield(L, tableindex, &key[0]);

Steps to reproduce

• Clone
• cmake et al

Specifications

Please provide details of your development environment.

• brand new Ubuntu 24.04 machine setup with the apt package list defined for 22.04

I get it's not a release and I don't know if you run the no breaking master/main rule.

[DennisOSRM]

Can you post the output from the cmake run? Probably an incompatibility of dependencies and/or compiler versions. At least that's the initial guess.

[madwax]

As asked for the build output:
putty.log

I think the problem is the compiler. I run into the same problem building v5.27.1 from git or downloaded source. I had a very quick poke around to fix it but somehow what I through was the fix failed due to key being something else other than a char[], I had to give up at that point.

[donno]

This looks like a duplicate of #6704, newer versions of GCC are picking up a problem in sol2 (a dependency of osrm-backend) or a GCC bug

[tombay]

It is a compiler bug. A workaround is to edit src/extractor/scripting_environment_lua.cpp and change some property assignments.
e.g. in
// version-dependent parts of the api
auto initV2Context = &
{

changefrom, to (for example)
< sol::optionalstd::int32_t u_turn_penalty = properties["u_turn_penalty"];

        std::int32_t i_turn_penalty = properties["u_turn_penalty"];
        sol::optional<std::int32_t> u_turn_penalty = i_turn_penalty;

The changed entries needed to change are:
sol::optionalstd::int32_t u_turn_penalty = properties["u_turn_penalty"];
sol::optional max_speed_for_map_matching = properties["max_speed_for_map_matching"];
sol::optional continue_straight_at_waypoint = properties["continue_straight_at_waypoint"];
sol::optional use_turn_restrictions = properties["use_turn_restrictions"];
sol::optional left_hand_driving = properties["left_hand_driving"];
sol::optional weight_precision = properties["weight_precision"];
sol::optional force_split_edges = properties["force_split_edges"];

I can't provide line numbers as it depends what build (tag version or master) you are building. (I did this on osrm-backend-6.0.0 as my master has problems with Obstacles).
The compiler error is related to "lazy" optimization of the strings. I moved allocation to the to of the if in ascending order and osrm-extract built.
e.g.
if (properties.valid())
{
sol::optionalstd::string weight_name = properties["weight_name"];
sol::optionalstd::int32_t u_turn_penalty = properties["u_turn_penalty"];
sol::optional weight_precision = properties["weight_precision"];
sol::optional force_split_edges = properties["force_split_edges"];
sol::optional left_hand_driving = properties["left_hand_driving"];
sol::optional use_turn_restrictions = properties["use_turn_restrictions"];
sol::optionalstd::int32_t traffic_signal_penalty = properties["traffic_signal_penalty"];
sol::optional max_speed_for_map_matching = properties["max_speed_for_map_matching"];
sol::optional continue_straight_at_waypoint = properties["continue_straight_at_waypoint"];

Whoever manages scripting_environment_lua.cpp could maybe do that. it could just be the order of the allocations within the block but I am happy that I can build it for now.

[tombay]

gcc version 13.3.0 (Ubuntu 13.3.0-6ubuntu2~24.04)

tom@metatom:~/Downloads/software/Project-OSRM/osrm-backend-6.0.0/src/extractor$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-linux-gnu/13/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 13.3.0-6ubuntu2~24.04' --with-bugurl=file:///usr/share/doc/gcc-13/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-13 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/libexec --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-libstdcxx-backtrace --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --enable-cet --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-13-fG75Ri/gcc-13-13.3.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-13-fG75Ri/gcc-13-13.3.0/debian/tmp-gcn/usr --enable-offload-defaulted --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 13.3.0 (Ubuntu 13.3.0-6ubuntu2~24.04) 

What I meant was - the code does the assignment followed by the test for != sol::nullopt. If you want to (i would) keep that then maybe just reordering the code to have the order above it might work.

[purew]

Compiling with latest clang works:

env CC=clang CXX=clang++ cmake .. -GNinja
ninja