using CXX-Modules: error: no matching function for call to 'make_tag' while trying rfl::json::write() (and error: recursive lazy load)

[Urfoex]

Been trying to move BooleanColumnView.hpp, FloatColumnOrFloatColumnView.hpp and StringColumnOrStringColumnView.hpp into a module.

Sample code: modules.tar.gz

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Compiling with Clang 18.1.8 gives:

/home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/../parsing/Parser_tagged_union.hpp:198:24: error: no matching function for call to 'make_tag'
  198 |       const auto tag = internal::make_tag<_discriminator, T>(_val);
      |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/../parsing/Parser_tagged_union.hpp:185:26: note: in instantiation of function template specialization 'rfl::parsing::Parser<rfl::json::Reader, rfl::json::Writer, rfl::TaggedUnion<internal::StringLiteral<10>{{"operator_"}}, commands::FloatColumnOrFloatColumnView::FloatArangeOp, commands::FloatColumnOrFloatColumnView::FloatAsTSOp, commands::FloatColumnOrFloatColumnView::FloatBinaryOp, commands::FloatColumnOrFloatColumnView::FloatConstOp, commands::FloatColumnOrFloatColumnView
::FloatFromBooleanOp, commands::FloatColumnOrFloatColumnView::FloatFromStringOp, commands::FloatColumnOrFloatColumnView::FloatRandomOp, commands::FloatColumnOrFloatColumnView::FloatRowidOp, commands::FloatColumnOrFloatColumnView::FloatSubselectionOp, commands::FloatColumnOrFloatColumnView::FloatUnaryOp, commands::FloatColumnOrFloatColumnView::FloatUpdateOp, commands::FloatColumnOrFloatColumnView::FloatColumnOp, commands::FloatColumnOrFloatColumnView::FloatWithSubrolesOp, commands::FloatColumnOrFloatColumnView::FloatWithUnitOp>, rfl::Pr
ocessors<>>::wrap_if_necessary<commands::FloatColumnOrFloatColumnView::FloatArangeOp>' requested here
  185 |     const auto wrapped = wrap_if_necessary<T>(_val);
      |                          ^
/home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/../parsing/Parser_tagged_union.hpp:68:7: note: in instantiation of function template specialization 'rfl::parsing::Parser<rfl::json::Reader, rfl::json::Writer, rfl::TaggedUnion<internal::StringLiteral<10>{{"operator_"}}, commands::FloatColumnOrFloatColumnView::FloatArangeOp, commands::FloatColumnOrFloatColumnView::FloatAsTSOp, commands::FloatColumnOrFloatColumnView::FloatBinaryOp, commands::FloatColumnOrFloatColumnView::FloatConstOp, commands::FloatColumnOrFloatColumnView::
FloatFromBooleanOp, commands::FloatColumnOrFloatColumnView::FloatFromStringOp, commands::FloatColumnOrFloatColumnView::FloatRandomOp, commands::FloatColumnOrFloatColumnView::FloatRowidOp, commands::FloatColumnOrFloatColumnView::FloatSubselectionOp, commands::FloatColumnOrFloatColumnView::FloatUnaryOp, commands::FloatColumnOrFloatColumnView::FloatUpdateOp, commands::FloatColumnOrFloatColumnView::FloatColumnOp, commands::FloatColumnOrFloatColumnView::FloatWithSubrolesOp, commands::FloatColumnOrFloatColumnView::FloatWithUnitOp>, rfl::Proc
essors<>>::write_wrapped<commands::FloatColumnOrFloatColumnView::FloatArangeOp, rfl::parsing::Parent<rfl::json::Writer>::Root>' requested here
   68 |       write_wrapped(_w, _val, _parent);
      |       ^
/home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/../parsing/Parser_default.hpp:78:55: note: in instantiation of function template specialization 'rfl::parsing::Parser<rfl::json::Reader, rfl::json::Writer, rfl::TaggedUnion<internal::StringLiteral<10>{{"operator_"}}, commands::FloatColumnOrFloatColumnView::FloatArangeOp, commands::FloatColumnOrFloatColumnView::FloatAsTSOp, commands::FloatColumnOrFloatColumnView::FloatBinaryOp, commands::FloatColumnOrFloatColumnView::FloatConstOp, commands::FloatColumnOrFloatColumnView::Floa
tFromBooleanOp, commands::FloatColumnOrFloatColumnView::FloatFromStringOp, commands::FloatColumnOrFloatColumnView::FloatRandomOp, commands::FloatColumnOrFloatColumnView::FloatRowidOp, commands::FloatColumnOrFloatColumnView::FloatSubselectionOp, commands::FloatColumnOrFloatColumnView::FloatUnaryOp, commands::FloatColumnOrFloatColumnView::FloatUpdateOp, commands::FloatColumnOrFloatColumnView::FloatColumnOp, commands::FloatColumnOrFloatColumnView::FloatWithSubrolesOp, commands::FloatColumnOrFloatColumnView::FloatWithUnitOp>, rfl::Processo
rs<>>::write<rfl::parsing::Parent<rfl::json::Writer>::Root>' requested here
   78 |         Parser<R, W, ReflectionType, ProcessorsType>::write(_w, r, _parent);
      |                                                       ^
/home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/write.hpp:30:33: note: in instantiation of function template specialization 'rfl::parsing::Parser<rfl::json::Reader, rfl::json::Writer, commands::FloatColumnOrFloatColumnView, rfl::Processors<>>::write<rfl::parsing::Parent<rfl::json::Writer>::Root>' requested here
   30 |   Parser<T, Processors<Ps...>>::write(w, _obj, typename ParentType::Root{});
      |                                 ^
/home/manuel/Projects/experiments/modules/main.cpp:39:16: note: in instantiation of function template specialization 'rfl::json::write<commands::FloatColumnOrFloatColumnView>' requested here
   39 |     rfl::json::write(floatColumnOrFloatColumnView);
      |                ^
In file included from /home/manuel/Projects/experiments/modules/main.cpp:3:
In file included from /home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/write.hpp:16:
In file included from /home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/Parser.hpp:4:
In file included from /home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/../parsing/Parser.hpp:23:

/home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/../parsing/Parser_tagged_union.hpp:185:26: error: no matching function for call to 'wrap_if_necessary'
  185 |     const auto wrapped = wrap_if_necessary<T>(_val);
      |                          ^~~~~~~~~~~~~~~~~~~~
/home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/../parsing/Parser_tagged_union.hpp:68:7: note: in instantiation of function template specialization 'rfl::parsing::Parser<rfl::json::Reader, rfl::json::Writer, rfl::TaggedUnion<internal::StringLiteral<10>{{"operator_"}}, commands::FloatColumnOrFloatColumnView::FloatArangeOp, commands::FloatColumnOrFloatColumnView::FloatAsTSOp, commands::FloatColumnOrFloatColumnView::FloatBinaryOp, commands::FloatColumnOrFloatColumnView::FloatConstOp, commands::FloatColumnOrFloatColumnView::
FloatFromBooleanOp, commands::FloatColumnOrFloatColumnView::FloatFromStringOp, commands::FloatColumnOrFloatColumnView::FloatRandomOp, commands::FloatColumnOrFloatColumnView::FloatRowidOp, commands::FloatColumnOrFloatColumnView::FloatSubselectionOp, commands::FloatColumnOrFloatColumnView::FloatUnaryOp, commands::FloatColumnOrFloatColumnView::FloatUpdateOp, commands::FloatColumnOrFloatColumnView::FloatColumnOp, commands::FloatColumnOrFloatColumnView::FloatWithSubrolesOp, commands::FloatColumnOrFloatColumnView::FloatWithUnitOp>, rfl::Proc
essors<>>::write_wrapped<commands::FloatColumnOrFloatColumnView::FloatConstOp, rfl::parsing::Parent<rfl::json::Writer>::Root>' requested here
   68 |       write_wrapped(_w, _val, _parent);
      |       ^
/home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/../parsing/Parser_default.hpp:78:55: note: in instantiation of function template specialization 'rfl::parsing::Parser<rfl::json::Reader, rfl::json::Writer, rfl::TaggedUnion<internal::StringLiteral<10>{{"operator_"}}, commands::FloatColumnOrFloatColumnView::FloatArangeOp, commands::FloatColumnOrFloatColumnView::FloatAsTSOp, commands::FloatColumnOrFloatColumnView::FloatBinaryOp, commands::FloatColumnOrFloatColumnView::FloatConstOp, commands::FloatColumnOrFloatColumnView::Floa
tFromBooleanOp, commands::FloatColumnOrFloatColumnView::FloatFromStringOp, commands::FloatColumnOrFloatColumnView::FloatRandomOp, commands::FloatColumnOrFloatColumnView::FloatRowidOp, commands::FloatColumnOrFloatColumnView::FloatSubselectionOp, commands::FloatColumnOrFloatColumnView::FloatUnaryOp, commands::FloatColumnOrFloatColumnView::FloatUpdateOp, commands::FloatColumnOrFloatColumnView::FloatColumnOp, commands::FloatColumnOrFloatColumnView::FloatWithSubrolesOp, commands::FloatColumnOrFloatColumnView::FloatWithUnitOp>, rfl::Processo
rs<>>::write<rfl::parsing::Parent<rfl::json::Writer>::Root>' requested here
   78 |         Parser<R, W, ReflectionType, ProcessorsType>::write(_w, r, _parent);
      |                                                       ^
/home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/write.hpp:30:33: note: in instantiation of function template specialization 'rfl::parsing::Parser<rfl::json::Reader, rfl::json::Writer, commands::FloatColumnOrFloatColumnView, rfl::Processors<>>::write<rfl::parsing::Parent<rfl::json::Writer>::Root>' requested here
   30 |   Parser<T, Processors<Ps...>>::write(w, _obj, typename ParentType::Root{});
      |                                 ^
/home/manuel/Projects/experiments/modules/main.cpp:39:16: note: in instantiation of function template specialization 'rfl::json::write<commands::FloatColumnOrFloatColumnView>' requested here
   39 |     rfl::json::write(floatColumnOrFloatColumnView);
      |                ^
/home/manuel/.conan2/p/b/refleff5a34aa1639b/p/include/rfl/json/../parsing/Parser_tagged_union.hpp:193:15: note: candidate template ignored: substitution failure [with T = commands::FloatColumnOrFloatColumnView::FloatConstOp]
  193 |   static auto wrap_if_necessary(const T& _val) noexcept {
      |               ^

clang.log

This is related to rfl::json::write(floatColumnOrFloatColumnView);
Without this, it compiles and runs.

---

Compiling with GCC 14.2.0 gives:

commands.ColumnOrColumnView:StringColumnOrStringColumnView: note: unable to represent further imported source locations
/home/manuel/Projects/experiments/modules/BooleanColumnView.ixx:26:78: error: recursive lazy load
   26 |         rfl::Literal<"and", "bool_equal_to", "bool_not_equal_to", "or", "xor">;
      |                                                                              ^
/home/manuel/Projects/experiments/modules/BooleanColumnView.ixx:26:78: fatal error: failed to load pendings for ‘rfl::internal::StringLiteral’

gcc.log

This is not specific to rfl::Literal, I also see it e.g. with rfl::Ref
Not sure, if it is something missing in GCC, or something fixable in rfl.

[GregTheMadMonk]

I've attempted to port an older version of rfl to build as a module in this commit. The problem is that some functions are marked static, and static functions are not exported from modules. You need to either replace it manually, like I did, or maybe rfl devs should replace static functions in headers with inline ones...

About the GCC issue - no idea. Try to fix Clang, maybe GCC will start working too :)

[Urfoex]

I have a working sample with clang 18 and 19
reflectcpp-modules.tar.gz

It just needs the static be gone from https://github.com/getml/reflect-cpp/blob/main/include/rfl/internal/variant/is_alternative_type.hpp#L11

Then it compiles and runs.

$ ./build_clang/modules 
Module1: {"ts":{},"literal":"Literal","tuple":["tuple"],"tagged_union":{"tagged_union":"Simple"},"variant":{}}
Module2: {"tuple":["tuple"],"result":"result","literal":"Literal","ts":{}}

Basically: You can't export entities with internal linkage.
And static functions are in that category:
https://vector-of-bool.github.io/2019/03/31/modules-2.html

With the adjustment, it works for this small example.
There might be other places, where a change is needed, for a bigger project, using more features of reflect-cpp.