What does "** Fatal error: Creation of import library not supported for this toolchain" mean?

[jonahbeckford]

The original issue is at dbuenzli/tsdl#96 (comment)

The relevant portions are the following when compiling tsdl.v1.1.0:

 ocamlfind ocamlopt -shared -linkall -thread src/libtsdl_stubs.lib -ccopt -LY:/source/tsdl/_opam/share/dkcoder-c/debug/lib/pkgconfig/../../lib -cclib dlltsdl_stubs.dll -package 'ctypes ctypes.foreign' -I src src/tsdl.cmxa -o src/tsdl.cmxs
+  ocamlfind ocamlopt -shared -linkall -thread src/libtsdl_stubs.lib -ccopt -LY:/source/tsdl/_opam/share/dkcoder-c/debug/lib/pkgconfig/../../lib -cclib dlltsdl_stubs.dll -package 'ctypes ctypes.foreign' -I src src/tsdl.cmxa -o src/tsdl.cmxs
** Fatal error: Creation of import library not supported for this toolchain

File "caml_startup", line 1:

Error: Error during linking (exit code 2)

Command exited with code 2.
pkg.ml: [ERROR] cmd ["ocamlbuild" "-use-ocamlfind" "-classic-display" "-j" "4" "-tag" "debug"
     "-build-dir" "_build" "opam" "pkg/META" "CHANGES.md" "LICENSE.md"
     "README.md" "src/tsdl.lib" "src/tsdl.cmxs" "src/tsdl.cmxa"
     "src/tsdl.cma" "src/tsdl.cmx" "src/tsdl.cmi" "src/tsdl.mli"
     "src/tsdl_consts.cmx" "src/dlltsdl_stubs.dll" "src/libtsdl_stubs.lib"
     "src/top/tsdl_top.lib" "src/top/tsdl_top.cmxs" "src/top/tsdl_top.cmxa"
     "src/top/tsdl_top.cma" "src/top/tsdl_top.cmx" "src/tsdl_top_init.ml"
     "doc/index.mld" "test/min.ml" "test/minc.c"]: exited with 10

I've never seen this error before and I assume one of the changes in dbuenzli/tsdl@v1.0.0...v1.1.0#diff-4fd5555cf41c3863fcb3a92e92540c4f4f88b744bf3ef779f27f23760787dfb1 is triggering this flexdll error.

[jonahbeckford]

This is just weird output when a .dll is supplied rather than a .lib but unrelated to a root cause. Closing.