ocamlPackages.llvm: build with llvm_8

pkgs/development/ocaml-modules/llvm/default.nix

@@ -10,18 +10,20 @@ stdenv.mkDerivation {
   buildInputs = [ python cmake llvm ocaml findlib ctypes ];
 
   patches = [ (fetchpatch {
-    url = https://raw.githubusercontent.com/ocaml/opam-repository/master/packages/llvm/llvm.3.9/files/cmake.patch;
-    sha256 = "1fcc6ylfiw1npdhx7mrsj7h0dx7cym7i9664kpr76zqazb52ikm9";
+    url = https://raw.githubusercontent.com/ocaml/opam-repository/2bdc193f5a9305ea93bf0f0dfc1fbc327c8b9306/packages/llvm/llvm.7.0.0/files/fix-shared.patch;
+    sha256 = "1p98j3b1vrryfn1xa7i50m6mmm4dyw5ldafq6kyh9sfmdihz4zsx";
   })];
 
-  cmakeFlags = [ "-DLLVM_OCAML_OUT_OF_TREE=TRUE" ];
+  cmakeFlags = [
+    "-DLLVM_OCAML_OUT_OF_TREE=TRUE"
+    "-DLLVM_OCAML_INSTALL_PATH=${placeholder "out"}/ocaml"
+  ];
 
   buildFlags = "ocaml_all";
 
   installFlags = "-C bindings/ocaml";
 
   postInstall = ''
-    mv $out/lib/ocaml $out/ocaml
     mkdir -p $OCAMLFIND_DESTDIR/
     mv $out/ocaml $OCAMLFIND_DESTDIR/llvm
     mv $OCAMLFIND_DESTDIR/llvm/META{.llvm,}

pkgs/top-level/ocaml-packages.nix

@@ -391,7 +391,7 @@ let
     linenoise = callPackage ../development/ocaml-modules/linenoise { };
 
     llvm = callPackage ../development/ocaml-modules/llvm {
-      llvm = pkgs.llvm_39;
+      llvm = pkgs.llvm_8;
     };
 
     logs = callPackage ../development/ocaml-modules/logs {