Cxxmodule with ROOT_GENERATE_DICTIONARY

[laurent.aphecetche]

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This is in relation to the comment of @pcanal in

Clarification needed on pcm dictionary files

Do I understand correctly that, if my dictionary was correctly generated in the first place (i.e. complete?) , the includes would not even have to be “reparsed” (and so their location would be irrelevant) ? This is true only if the types in the dictionary are only used for I/O. If they are used for interpretation then you need the dictionary (because the dictionary does not register anything about methods, for example). It is likely you have a missing request for dictionary in your LinkDef/…

In the longer term, the need for header file will be replaced by the generation of a Clang C++ module. You can test this via the MODULE option of ROOT_GENERATE_DICTIONARY in CMake or directly the -cxxmodule option of rootcling

I actually already use the MODULE option of ROOT_GENERATE_DICTIONARY in my projects’s CMakeLists and still it seems the header files are somehow required.

Looking more closely to the ROOT_GENERATE_DICTIONARY macro I would conclude that I need to use a Root that has been compiled with the runtime_cxxmodules` option for this to work. Is that correct ?

ROOT Version: 6.34.10
Platform: macosxarm64
Compiler: Clang

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