Build opam with msvc in the msvc images

Author: MisterDA

src-opam/opam.ml

@@ -471,32 +471,29 @@ let windows_msvc_opam2 ?win10_revision ?winget ?(labels = []) ~opam_hashes
   let winget_image, winget_setup =
     install_winget ?win10_revision ?winget version
   in
+  let packages, vs_build_tools =
+    ( Windows.Cygwin.msvc_packages,
+      Windows.install_visual_studio_build_tools
+        [
+          "Microsoft.VisualStudio.Component.VC.Tools.x86.x64";
+          "Microsoft.VisualStudio.Component.Windows10SDK.18362";
+        ] )
+  in
   let opams_image =
     Windows.header ~alias:"opam-builder" ?win10_revision ~version ()
     @@ Windows.sanitize_reg_path ()
-    @@ Windows.Cygwin.(
-         install_cygwin
-           ~extra:
-             ("git" :: "patch" :: "mingw64-x86_64-gcc-g++"
-            :: "mingw64-i686-gcc-g++" :: mingw_packages)
-           ())
+    @@ vs_build_tools
+    @@ Windows.Cygwin.install_cygwin ~extra:packages ()
     @@ install_opams_windows opam_master_hash opam_branches
   in
   (* 2022-10-12: Docker Engine 20.10.18 on Windows fails copying
      C:\cygwin64, so we cannot build Cygwin in a separate image. *)
   let ocaml_for_windows =
-    let packages, vs_build_tools =
-      ( Windows.Cygwin.msvc_packages,
-        Windows.install_visual_studio_build_tools
-          [
-            "Microsoft.VisualStudio.Component.VC.Tools.x86.x64";
-            "Microsoft.VisualStudio.Component.Windows10SDK.18362";
-          ] )
-    in
     let ofw_packages, ofw_setup = Windows.Cygwin.install_ocaml_for_windows () in
-    Windows.Cygwin.install_cygwin ~msvs_tools:true
-      ~extra:(packages @ ofw_packages) ()
-    @@ vs_build_tools @@ ofw_setup
+    vs_build_tools
+    @@ Windows.Cygwin.install_cygwin ~msvs_tools:true
+         ~extra:(packages @ ofw_packages) ()
+    @@ ofw_setup
   in
   parser_directive (`Escape '`')
   @@ comment "Autogenerated by OCaml-Dockerfile scripts"
@@ -505,7 +502,7 @@ let windows_msvc_opam2 ?win10_revision ?winget ?(labels = []) ~opam_hashes
   @@ label (("distro_style", "windows") :: labels)
   @@ user "ContainerAdministrator"
   @@ Windows.sanitize_reg_path ()
-  @@ winget_setup @@ ocaml_for_windows
+  @@ ocaml_for_windows @@ winget_setup
   @@ copy_opams_windows opam_branches
   @@ Windows.Cygwin.setup () @@ Windows.Cygwin.Git.init ()