Install the "flexdll" package in the toolchains directory on windows

[gridbugs]

Dune installs the ocaml compiler package to ~/.cache/dune/toolchains when using package management features. On unix systems the compiler has no dependencies so the only package that must be installed this way is the compiler itself. However on windows the compiler (specifically ocaml-base-compiler) depends on the package flexdll. On windows, flexdll must be installed to the toolchains directory along with the compiler in order to resolve the compiler's dependency on flexdll.

[gridbugs]

Note that dune currently has some logic for rewriting the compiler's build and install commands to install the package to the toolchains directory rather than inside the project's _build directory. This logic is highly specialized to build and install commands for the ocaml-base-compiler's opam package ind it won't generalize to flexdll.

[gridbugs]

This turns out not to be necessary. When ocaml is built it needs access to flexdll but after that point flexdll can be removed. Thus there's no reason to keep flexdll around in a user-wide place such as the toolchains dir. Installing it into the _build directory of the first dune project that needs the compiler is an acceptable solution, so no work here is needed.

[nojb]

When ocaml is built it needs access to flexdll but after that point flexdll can be removed.

Are you sure? flexlink is used as a linker on Windows, it is used whenever OCaml builds an executable or plugin in native code.

[gridbugs]

That has been my experience. I built and installed the compiler manually, pointing ./configure at a checkout of flexdll. Then I deleted flexdll and tried using the compiler and it worked fine. @dra27 is there a case where it's necessary to still have flexdll around when the compiler is running?

[nojb]

That has been my experience. I built and installed the compiler manually, pointing ./configure at a checkout of flexdll. Then I deleted flexdll and tried using the compiler and it worked fine. @dra27 is there a case where it's necessary to still have flexdll around when the compiler is running?

Note that depending on how you configure OCaml, flexlink will be installed next to the compiler.