switch: allow local compiler switch creation (ocaml#3720)

src/client/opamAuxCommands.ml

@@ -491,13 +491,13 @@ let get_compatible_compiler ?repos rt dir =
        (OpamStd.Format.itemize OpamPackage.to_string
           (OpamPackage.Set.elements local_packages));
      if OpamConsole.confirm "Do you want to create an empty switch regardless?"
-     then []
+     then [], false
      else OpamStd.Sys.exit_because `Aborted)
   else
   let compilers = OpamPackage.Set.inter compilers installable in
   try
     [OpamSolution.eq_atom_of_package
-       (OpamPackage.Set.choose_one compilers)]
+       (OpamPackage.Set.choose_one compilers)], true
   with
   | Not_found when not (OpamPackage.Set.is_empty local_packages) ->
     OpamConsole.warning
@@ -507,15 +507,15 @@ let get_compatible_compiler ?repos rt dir =
        OpamConsole.confirm
          "Create the switch with no specific compiler selected, and attempt to \
           continue?"
-    then []
+    then [], false
     else OpamStd.Sys.exit_because `Aborted
  | Failure _ | Not_found ->
    (* Find a matching compiler from the default selection *)
    let default_compiler =
      OpamFile.Config.default_compiler gt.config
    in
    if default_compiler = Empty then
-     (OpamConsole.warning "No compiler selected"; [])
+     (OpamConsole.warning "No compiler selected"; [], false)
    else
    let candidates = OpamFormula.to_dnf default_compiler in
    try
@@ -545,7 +545,7 @@ let get_compatible_compiler ?repos rt dir =
             Some (OpamSolution.eq_atoms_of_packages compiler)
           else None
        )
-       candidates
+       candidates, false
    with Not_found ->
       OpamConsole.warning
         "The default compiler selection: %s\n\
@@ -557,5 +557,5 @@ let get_compatible_compiler ?repos rt dir =
       if OpamConsole.confirm
           "You may also proceed, with no specific compiler selected. \
            Do you want to?"
-      then []
+      then [], false
       else OpamStd.Sys.exit_because `Aborted

src/client/opamAuxCommands.mli

@@ -91,4 +91,4 @@ val simulate_autopin:
     warning, and returns the empty list after user confirmation. *)
 val get_compatible_compiler:
   ?repos:repository_name list ->
-  'a repos_state -> dirname -> atom list
+  'a repos_state -> dirname -> atom list * bool

src/client/opamCommands.ml

@@ -2040,7 +2040,7 @@ let switch =
       match packages, compiler_opt, OpamSwitch.is_external switch with
       | None, None, false ->
         OpamSwitchCommand.guess_compiler_package ?repos rt
-          (OpamSwitch.to_string switch)
+          (OpamSwitch.to_string switch), false
       | None, None, true ->
         OpamAuxCommands.get_compatible_compiler ?repos rt
           (OpamFilename.dirname_dir
@@ -2049,7 +2049,7 @@ let switch =
         OpamStd.Option.Op.(
           ((compiler_opt >>|
             OpamSwitchCommand.guess_compiler_package ?repos rt) +! []) @
-          packages +! [])
+          packages +! []), false
     in
     let param_compiler = function
       | [] -> None
@@ -2109,18 +2109,20 @@ let switch =
       OpamGlobalState.with_ `Lock_write @@ fun gt ->
       let repos, rt = get_repos_rt gt repos in
       let switch = OpamSwitch.of_string switch_arg in
-      let packages =
+      let packages, local_compiler =
         compiler_packages rt ?repos switch (param_compiler params)
       in
       let _gt, st =
         OpamSwitchCommand.install gt ~rt
           ?synopsis:descr ?repos
           ~update_config:(not no_switch)
           ~packages
+          ~local_compiler
           switch
       in
       let st =
-        if not no_install && not empty && OpamSwitch.is_external switch then
+        if not no_install && not empty &&
+           OpamSwitch.is_external switch && not local_compiler then
           let st, atoms =
             OpamAuxCommands.autopin st ~simulate:deps_only ~quiet:true
               [`Dirname (OpamFilename.Dir.of_string switch_arg)]

src/client/opamSwitchCommand.ml

@@ -269,7 +269,7 @@ let install_compiler_packages t atoms =
   OpamSolution.check_solution ~quiet:OpamClientConfig.(not !r.show) t result;
   t
 
-let install gt ?rt ?synopsis ?repos ~update_config ~packages switch =
+let install gt ?rt ?synopsis ?repos ~update_config ~packages ?(local_compiler=false) switch =
   let update_config = update_config && not (OpamSwitch.is_external switch) in
   let old_switch_opt = OpamFile.Config.switch gt.config in
   let comp_dir = OpamPath.Switch.root gt.root switch in
@@ -311,6 +311,13 @@ let install gt ?rt ?synopsis ?repos ~update_config ~packages switch =
       in
       { st with switch; available_packages }
   in
+  let st =
+    if OpamSwitch.is_external switch && local_compiler then
+      OpamAuxCommands.autopin st ~quiet:true
+        [`Dirname (OpamFilename.Dir.of_string (OpamSwitch.to_string switch))]
+      |> fst
+    else st
+  in
   let packages =
     try OpamSolution.sanitize_atom_list st packages
     with e ->

src/client/opamSwitchCommand.mli

@@ -24,7 +24,9 @@ val install:
   ?synopsis:string ->
   ?repos:repository_name list ->
   update_config:bool ->
-  packages:atom conjunction -> switch ->
+  packages:atom conjunction -> 
+  ?local_compiler:bool ->
+  switch ->
   unlocked global_state * rw switch_state
 
 (** Install a compiler's base packages *)