Apply switch-defaults

opam switch create now also supports the --default-config and --config
also found in opam init. For opam switch create, --config specifies a
switch-defaults file, not an opamrc, but if not specified, opam will
look for a switch-defaults section in opamrc.

Signed-off-by: David Allsopp <david.allsopp@metastack.com>

src/client/opamCommands.ml

@@ -257,6 +257,9 @@ let init =
         ~init_config ?repo ~bypass_checks
         shell dot_profile update_config
     in
+    let switch_defaults =
+      OpamStd.Option.default OpamInitDefaults.switch_defaults (OpamFile.InitConfig.switch_defaults init_config)
+    in
     if not no_compiler &&
        OpamFile.Config.installed_switches gt.config = [] then
       match compiler with
@@ -267,7 +270,7 @@ let init =
         OpamConsole.header_msg "Creating initial switch (%s)"
           (OpamFormula.string_of_atoms packages);
         OpamSwitchCommand.install
-          gt ~rt ~packages ~update_config:true (OpamSwitch.of_string comp)
+          gt ~rt ~packages ~update_config:true ~switch_defaults (OpamSwitch.of_string comp)
         |> ignore
       | None ->
         let candidates = OpamFormula.to_dnf default_compiler in
@@ -286,7 +289,7 @@ let init =
           OpamConsole.header_msg "Creating initial switch (%s)"
             (OpamFormula.string_of_atoms packages);
           OpamSwitchCommand.install
-            gt ~rt ~packages ~update_config:true
+            gt ~rt ~packages ~update_config:true ~switch_defaults
             (OpamSwitch.of_string "default")
           |> ignore
         | None ->
@@ -1799,11 +1802,67 @@ let switch =
        existing switch."
       Arg.(some string) None
   in
+  let config_file =
+    mk_opt_all ["config"] "FILE"
+      "Use the given init config file. If repeated, latest has the highest \
+       priority ($(b,i.e.) each field gets its value from where it was defined \
+       latest). Specifying a URL pointing to a config file instead is \
+       allowed."
+      OpamArg.url
+  in
+  let no_config_file =
+    mk_flag ["no-opamrc"]
+      (Printf.sprintf
+      "Don't read `/etc/opamrc' or `~%s.opamrc': use the default settings and \
+       the files specified through $(b,--config) only" Filename.dir_sep)
+  in
   let switch
       global_options build_options command print_short
-      no_switch packages empty descr repos params =
+      no_switch packages empty descr config_file no_config_file repos params =
     apply_global_options global_options;
     apply_build_options build_options;
+    let config_files =
+      (if no_config_file then []
+       else OpamStd.List.filter_map (fun f -> if OpamFile.exists f then Some (OpamFile.to_string f |> OpamFilename.of_string, `InitConfig) else None) (OpamPath.init_config_files ()))
+      @ List.map (fun url ->
+          match OpamUrl.local_file url with
+          | Some f -> (f, `SwitchDefaults)
+          | None ->
+            let f = OpamFilename.of_string (OpamSystem.temp_file "conf") in
+            OpamProcess.Job.run (OpamDownload.download_as ~overwrite:false url f);
+            let hash = OpamHash.compute ~kind:`SHA256 (OpamFilename.to_string f) in
+            if OpamConsole.confirm
+                "Using configuration file from %s. \
+                 Please verify the following SHA256:\n    %s\n\
+                 Is this correct ?"
+                (OpamUrl.to_string url) (OpamHash.contents hash)
+            then (f, `SwitchDefaults)
+            else OpamStd.Sys.exit 10
+        ) config_file
+    in
+    let switch_defaults =
+      try
+        OpamConsole.note "Will configure switch from built-in defaults%s."
+          (OpamStd.List.concat_map ~nil:"" ~left:", " ", "
+             (fun (f, _) -> OpamFilename.to_string f) config_files);
+        List.fold_left (fun acc (f, kind) ->
+          let config =
+            match kind with
+            | `InitConfig ->
+                OpamFile.InitConfig.read (OpamFile.make f) |> OpamFile.InitConfig.switch_defaults
+            | `SwitchDefaults ->
+                Some (OpamFile.SwitchDefaults.read (OpamFile.make f))
+          in
+          OpamStd.Option.map_default (OpamFile.SwitchDefaults.add acc) acc config)
+          OpamInitDefaults.switch_defaults
+          config_files
+      with e ->
+        OpamConsole.error
+          "Error in configuration file, fix it, use '--no-opamrc', or check \
+           your '--config FILE' arguments:";
+        OpamConsole.errmsg "%s\n" (Printexc.to_string e);
+        OpamStd.Sys.exit 10
+    in
     let packages =
       match packages, empty with
       | None, true -> Some []
@@ -1885,7 +1944,7 @@ let switch =
         OpamSwitchCommand.install gt ~rt
           ?synopsis:descr ?repos
           ~update_config:(not no_switch)
-          ~packages
+          ~packages ~switch_defaults
           switch
       in
       ignore (OpamSwitchState.unlock st);
@@ -1985,7 +2044,7 @@ let switch =
              $global_options $build_options $command
              $print_short_flag
              $no_switch
-             $packages $empty $descr $repos $params)),
+             $packages $empty $descr $config_file $no_config_file $repos $params)),
   term_info "switch" ~doc ~man
 
 (* PIN *)

src/client/opamSwitchCommand.ml

@@ -248,7 +248,7 @@ 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 ~switch_defaults 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
@@ -263,7 +263,51 @@ let install gt ?rt ?synopsis ?repos ~update_config ~packages switch =
   let gt, st =
     if not (OpamStateConfig.(!r.dryrun) || OpamClientConfig.(!r.show)) then
       let gt =
-        OpamSwitchAction.create_empty_switch gt ?synopsis ?repos switch
+        let env full_var =
+          let open OpamVariable.Full in
+          match scope full_var with
+          | Global ->
+              OpamPackageVar.resolve_global gt full_var
+          | Self ->
+              None
+          | Package name ->
+              match variable full_var |> OpamVariable.to_string with
+              | "installed" ->
+                  Some (B (List.exists (fun (package, _) -> OpamPackage.Name.compare name package = 0) packages))
+              (*| "version" ->
+                  begin
+                    try
+                      let (_, version) =
+                        List.find (fun (package, version) -> OpamPackage.Name.compare name package = 0) packages
+                      in
+                      Some (S (OpamPackage.Version.to_string version))
+                    with Not_found ->
+                      None
+                  end*)
+              | _ ->
+                  None
+        in
+        let configure_switch conf =
+          let variables =
+            (* @@DRA Should be able to use description in the same way as for eval_variables *)
+            let f ((name, value, _description), filter) =
+              if OpamStd.Option.map_default (OpamFilter.eval_to_bool ~default:false env) true filter then
+                let value =
+                  match value with
+                  | B _ ->
+                      value
+                  | S value ->
+                      S (OpamFilter.expand_string (OpamPackageVar.resolve_global gt) value)
+                in
+                Some (name, value)
+              else
+                None
+            in
+            OpamStd.List.filter_map f (OpamFile.SwitchDefaults.switch_variables switch_defaults)
+          in
+          OpamFile.Switch_config.{conf with variables = conf.variables @ variables}
+        in
+        OpamSwitchAction.create_empty_switch gt ?synopsis ?repos ~configure_switch switch
       in
       if update_config then
         gt, OpamSwitchAction.set_current_switch `Lock_write gt ?rt switch

src/client/opamSwitchCommand.mli

@@ -24,7 +24,8 @@ val install:
   ?synopsis:string ->
   ?repos:repository_name list ->
   update_config:bool ->
-  packages:atom conjunction -> switch ->
+  packages:atom conjunction ->
+  switch_defaults: OpamFile.SwitchDefaults.t -> switch ->
   unlocked global_state * rw switch_state
 
 (** Install a compiler's base packages *)

src/state/opamSwitchAction.ml

@@ -16,7 +16,7 @@ open OpamPackage.Set.Op
 let log fmt = OpamConsole.log "SWACT" fmt
 let slog = OpamConsole.slog
 
-let gen_switch_config root ?(synopsis="") ?repos switch =
+let gen_switch_config root ?(synopsis="") ?repos ?(configure_switch = fun x -> x) switch =
   let vars =
     List.map (fun (s,p) -> OpamVariable.of_string s, S p) [
       ("user" ,
@@ -33,6 +33,7 @@ let gen_switch_config root ?(synopsis="") ?repos switch =
     (Prefix, OpamFilename.Dir.to_string (OpamPath.Switch.root root switch));
   ]
   in
+  configure_switch
   { OpamFile.Switch_config.
     opam_version = OpamVersion.current_nopatch;
     synopsis;
@@ -48,7 +49,7 @@ let install_switch_config root switch config =
     (OpamPath.Switch.switch_config root switch)
     config
 
-let create_empty_switch gt ?synopsis ?repos switch =
+let create_empty_switch gt ?synopsis ?repos ?configure_switch switch =
   log "create_empty_switch at %a" (slog OpamSwitch.to_string) switch;
   let root = gt.root in
   let switch_dir = OpamPath.Switch.root root switch in
@@ -62,7 +63,7 @@ let create_empty_switch gt ?synopsis ?repos switch =
     (* Create base directories *)
     OpamFilename.mkdir switch_dir;
 
-    let config = gen_switch_config root ?synopsis ?repos switch in
+    let config = gen_switch_config root ?synopsis ?repos ?configure_switch switch in
 
     OpamFilename.mkdir (OpamPath.Switch.lib_dir root switch config);
     OpamFilename.mkdir (OpamPath.Switch.stublibs root switch config);

src/state/opamSwitchAction.mli

@@ -18,6 +18,7 @@ open OpamStateTypes
     registers it in the global config and returns the updated global state *)
 val create_empty_switch:
   rw global_state -> ?synopsis:string -> ?repos:repository_name list ->
+  ?configure_switch:(OpamFile.Switch_config.t -> OpamFile.Switch_config.t) ->
   switch -> rw global_state
 
 (** Writes the current state file to disk (installed, pinned, root packages etc.).
@@ -33,6 +34,7 @@ val set_current_switch:
     prefix *)
 val gen_switch_config:
   dirname -> ?synopsis:string -> ?repos:repository_name list ->
+  ?configure_switch:(OpamFile.Switch_config.t -> OpamFile.Switch_config.t) ->
   switch -> OpamFile.Switch_config.t
 
 (** (Re-)install the configuration for a given root and switch *)