Fix the build for 4.02-4.04 on macOS and for 4.02-4.10 with MSVC on Windows #8
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Dune doesn't allow the modules list itself to be filtered, but it is possible to control the meaning of :standard by using (enabled_if ..) to assemble only the desired .ml and .mli in the build directory.
Code is now in src/ with nefarious trickery reserved for the dune file only.
Since these are only passed to OCaml 4.14+, we can take advantage of the clearer symbolic names.
ocamlopt on these versions of OCaml cannot create .cmxa files with no modules. On these versions, create a dummy CamlinternalCamlp_streams module whose name will be assumed never to clash as it uses the compiler's reserved prefix.
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I can confirm that this is working on MSVC 4.06-4.14 with only 4.06-4.10 having the dummy module in camlp_streams.cmxa. |
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Thanks for the fix @dra27, I confirm that it resolves the build failure on |
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I recently discovered that one can correctly trick Dune into creating empty libraries for some versions of OCaml, which allows the removal of the dynamic
dunefile. This PR then changes the build to be an empty library for OCaml 4.13 and earlier. This was originally considered in #5, but it breaks the build on MSVC prior to 4.11, so instead an empty library was only built for OCaml 4.07 to limit the damage to 4.02-4.07 on MSVC. It turns out the damage included in 4.02-4.04 on macOS.The solution proposed here is that for the offending versions of OCaml (that's 4.02-4.04 on macOS and 4.02-4.10 with MSVC on Windows), an empty module
CamlinternalCamlp_streamsis added to the library which works around the linker problems.A solution such as this was considered for the same problem in stdlib-shims, however it was rejected there because this issue affects the current versions of OCaml (the solution adopted in stdlib-shims was to fix OCaml itself). I think it's OK to use this trick here because we know that there was no
CamlinternalCamlp_streamsmodule in 4.02-4.10 and programs and libraries are not supposed to use names beginningCamlinternal. Most importantly, the number of releases in which this trick is used is fixed, unlike in stdlib-shims.