Missing modules in some libraries

[jonludlam]

A (relatively minor) consequence of the switch to using META/cma examination rather than using the dune-package metadata is that if there are 'modules without implementation' in a library, then these are no longer listed on the main documentation page (nor the sidebar). As an example see the tyxml docs. The tyxml.functor library has a dune file specifying that a few modules have no implementation, and for these dune installs the relevant cmi files but there are no implementation modules linked into the cma/cmxa files. OCaml is happy with this as the entire installed directory is added to the include path so it picks up all the cmis, but the problem is that voodoo is deciding which modules belong to which library by examining the cma files, thus the modules that dune considers to be part of the library are excluded.

The docs for the modules are actually built but they are 'orphaned', for example Svg_sigs.T.

One heuristic solution is that if there's only one library in the path, then we can assume all cmi files are associated with that library. This will work for all dune projects as dune enforces the one-lib-per-path constraint.

[sabine]

Thanks @jonludlam. It makes sense to apply this fix.