Add option to be able to use the default root

By default, opam-ci-check revdeps functionality uses a new opam switch
to not mess up a user's switches, etc. But, in CI we could use the
default switch and avoid creating a new separate switch, since we are
running in a container created for this purpose.

opam-ci-check/bin/main.ml

@@ -87,25 +87,26 @@ let lint package_specs local_repo_dir =
           |> Printf.sprintf "%s\n" |> Result.error
       | Error _ as e -> e)
 
-let show_revdeps pkg local_repo_dir no_transitive_revdeps =
+let show_revdeps pkg local_repo_dir no_transitive_revdeps use_default_root =
   (* Get revdeps for the package *)
   let revdeps =
     Revdeps.list_revdeps ?opam_repo:local_repo_dir
       ~transitive:(not no_transitive_revdeps)
-      pkg
+      ~use_default_root pkg
   in
   Revdeps.Display.packages revdeps;
   Ok ()
 
 let testing_revdeps_confirmed revdeps =
   OpamConsole.confirm "Do you want test %d revdeps?" (List.length revdeps)
 
-let test_revdeps pkg local_repo_dir use_dune no_transitive_revdeps =
+let test_revdeps pkg local_repo_dir use_dune no_transitive_revdeps
+    use_default_root =
   (* Get revdeps for the package *)
   let revdeps =
     Revdeps.list_revdeps ?opam_repo:local_repo_dir
       ~transitive:(not no_transitive_revdeps)
-      pkg
+      ~use_default_root pkg
   in
 
   (* Install and test the first reverse dependency *)
@@ -119,7 +120,7 @@ let test_revdeps pkg local_repo_dir use_dune no_transitive_revdeps =
     | true, None -> Error "Opam local repository path must be specified!\n"
     | false, _ ->
         let num_failed_installs =
-          Test.test_packages_with_opam pkg latest_versions
+          Test.test_packages_with_opam ~use_default_root pkg latest_versions
           |> Seq.map (fun e -> Printf.eprintf "%s\n" (Test.error_to_string e))
           |> Seq.length
         in
@@ -187,6 +188,13 @@ let no_transitive_revdeps =
   in
   Arg.value (Arg.flag info)
 
+let use_default_root =
+  let info =
+    Arg.info [ "use-default-root" ]
+      ~doc:"Use the default opam root in ~/.opam instead of creating a new one."
+  in
+  Arg.value (Arg.flag info)
+
 let use_dune_term =
   let info =
     Arg.info [ "d"; "use-dune" ]
@@ -305,7 +313,7 @@ let list_cmd =
   let term =
     Term.(
       const show_revdeps $ pkg_term $ local_opam_repo_term
-      $ no_transitive_revdeps)
+      $ no_transitive_revdeps $ use_default_root)
     |> to_exit_code
   in
   let info =
@@ -318,7 +326,7 @@ let test_cmd =
   let term =
     Term.(
       const test_revdeps $ pkg_term $ local_opam_repo_term $ use_dune_term
-      $ no_transitive_revdeps)
+      $ no_transitive_revdeps $ use_default_root)
     |> to_exit_code
   in
   let info =

opam-ci-check/lib/env.ml

@@ -7,12 +7,12 @@ let make_repo path =
   let repo_url = OpamUrl.parse path in
   { OpamTypes.repo_name; repo_url; repo_trust = None }
 
-let local_opam_root () =
-  let switch_dir = ".opam-revdeps" in
+let get_opam_root ?(use_default_root = false) () =
+  let switch_dir = if use_default_root then "~/.opam" else ".opam-revdeps" in
   OpamFilename.Dir.of_string switch_dir
 
-let create_local_switch_maybe repo_path =
-  let root_dir = local_opam_root () in
+let create_local_switch_maybe ?(use_default_root = false) repo_path =
+  let root_dir = get_opam_root ~use_default_root () in
   let create_switch_dir repo_path =
     OpamClientConfig.opam_init ~root_dir ();
     (* opam init*)
@@ -50,14 +50,14 @@ let create_local_switch_maybe repo_path =
     create_switch_dir repo_path)
   else ()
 
-let with_locked_switch () =
-  let root_dir = local_opam_root () in
+let with_locked_switch ?(use_default_root = false) () =
+  let root_dir = get_opam_root ~use_default_root () in
   OpamClientConfig.opam_init ~root_dir ();
   OpamGlobalState.with_ `Lock_none @@ fun gt ->
   OpamSwitchState.with_ `Lock_write gt
 
-let with_unlocked_switch () =
-  let root_dir = local_opam_root () in
+let with_unlocked_switch ?(use_default_root = false) () =
+  let root_dir = get_opam_root ~use_default_root () in
   OpamClientConfig.opam_init ~root_dir ();
   OpamGlobalState.with_ `Lock_none @@ fun gt ->
   OpamSwitchState.with_ `Lock_none gt

opam-ci-check/lib/revdeps.ml

@@ -59,12 +59,12 @@ let non_transitive_revdeps st package_set =
     all_known_packages
 
 let list_revdeps ?(opam_repo = "https://opam.ocaml.org") ?(transitive = true)
-    pkg =
-  (* Create local opam root and switch *)
-  Env.create_local_switch_maybe opam_repo;
+    ?(use_default_root = false) pkg =
+  (* Create local opam root and switch if required *)
+  if not use_default_root then Env.create_local_switch_maybe opam_repo;
   let package = OpamPackage.of_string pkg in
   let package_set = OpamPackage.Set.singleton package in
-  Env.with_unlocked_switch () (fun st ->
+  Env.with_unlocked_switch ~use_default_root () (fun st ->
       let transitive_deps =
         if transitive then transitive_revdeps st package_set
         else OpamPackage.Set.empty

opam-ci-check/lib/revdeps.mli

@@ -5,7 +5,11 @@
 (** Analyze and test the reverse dependencies of a package. *)
 
 val list_revdeps :
-  ?opam_repo:string -> ?transitive:bool -> string -> OpamPackage.t list
+  ?opam_repo:string ->
+  ?transitive:bool ->
+  ?use_default_root:bool ->
+  string ->
+  OpamPackage.t list
 (** [list_revdeps pkg] is a list of the transitive reverse dependencies of [pkg].
 
     @param opam_repo The package repository to use when calculating
@@ -14,6 +18,9 @@ val list_revdeps :
     @param transitive Whether or to list all transitive reverse dependencies.
     Defaults to [true].
 
+    @param use_default_root Whether or to use the default root ~/.opam or
+    create a new one. Defaults to [false].
+
     @param pkg The package for which reverse dependencies will be listed, in a
     form like ["pkgname.0.0.1"].
 

opam-ci-check/lib/test.ml

@@ -32,7 +32,8 @@ let test_package_with_opam_in_state st revdep =
          But, we may be able to do better, since we are not a shell script? *)
       Some (revdep, e)
 
-let test_packages_with_opam target_pkg revdeps_list =
+let test_packages_with_opam ?(use_default_root = false) target_pkg revdeps_list
+    =
   let target = OpamPackage.of_string target_pkg in
   match
     OpamConsole.confirm "Do you want test %d revdeps?"
@@ -44,7 +45,7 @@ let test_packages_with_opam target_pkg revdeps_list =
         ~confirm_level:`unsafe_yes (* Don't prompt for install / remove *) ();
       OpamConsole.msg "Installing reverse dependencies with pinned %s\n"
         (OpamPackage.to_string target);
-      Env.with_locked_switch () @@ fun st ->
+      Env.with_locked_switch ~use_default_root () @@ fun st ->
       let st' = OpamClient.install st [ pkg_atom target ] in
       revdeps_list |> List.to_seq
       |> Seq.filter_map (test_package_with_opam_in_state st')

opam-ci-check/lib/test.mli

@@ -7,7 +7,8 @@ type error = OpamPackage.t * exn
 
 val error_to_string : error -> string
 
-val test_packages_with_opam : string -> OpamPackage.t list -> error Seq.t
+val test_packages_with_opam :
+  ?use_default_root:bool -> string -> OpamPackage.t list -> error Seq.t
 (** [test_packages_with_opam package revdeps] is the sequence of errors encountered
     while trying to install and test all the packages in [revdeps].