Switch defaults configuration file

src/client/opamCommands.ml

@@ -361,6 +361,10 @@ let init =
       get_init_config ~no_sandboxing
         ~no_default_config_file:no_config_file ~add_config_file:config_file
     in
+    let switch_defaults =
+      OpamFile.InitConfig.switch_defaults init_config
+        |> OpamStd.Option.default OpamInitDefaults.switch_defaults
+    in
     let repo =
       OpamStd.Option.map (fun url ->
           let repo_url = OpamUrl.parse ?backend:repo_kind url in
@@ -384,7 +388,8 @@ 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
     | _ as nocomp ->
       if nocomp <> None then
@@ -406,7 +411,7 @@ 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 ->
@@ -2065,15 +2070,58 @@ let switch =
     mk_flag ["no-autoinstall"]
       "This option is deprecated."
   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 full no_install deps_only repos
-      d_alias_of d_no_autoinstall params =
+      d_alias_of d_no_autoinstall config_file no_config_file params =
    OpamArg.deprecated_option d_alias_of None
    "alias-of" (Some "opam switch <switch-name> <compiler>");
    OpamArg.deprecated_option d_no_autoinstall false "no-autoinstall" None;
     apply_global_options global_options;
     apply_build_options build_options;
+    let config_files =
+      let principal_config_files =
+        if no_config_file then []
+        else
+          let f f =
+            if OpamFile.exists f then
+              Some (OpamFile.to_string f |> OpamFilename.of_string, `InitConfig)
+            else
+              None
+          in
+          OpamStd.List.filter_map f (OpamPath.init_config_files ())
+      in
+      principal_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_because `Aborted
+        ) config_file
+    in
     let packages =
       match packages, empty with
       | None, true -> Some []
@@ -2152,6 +2200,29 @@ let switch =
         compilers;
       `Ok ()
     | Some `install, switch_arg::params ->
+      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_because `Configuration_error
+      in
       OpamGlobalState.with_ `Lock_write @@ fun gt ->
       with_repos_rt gt repos @@ fun (repos, rt) ->
       let switch = OpamSwitch.of_string switch_arg in
@@ -2163,6 +2234,7 @@ let switch =
           ?synopsis:descr ?repos
           ~update_config:(not no_switch)
           ~packages
+          ~switch_defaults
           ~local_compiler
           switch
       in
@@ -2323,7 +2395,8 @@ let switch =
              $print_short_flag
              $no_switch
              $packages $empty $descr $full $no_install $deps_only
-             $repos $d_alias_of $d_no_autoinstall $params)),
+             $repos $d_alias_of $d_no_autoinstall $config_file $no_config_file
+             $params)),
   term_info "switch" ~doc ~man
 
 (* PIN *)

src/client/opamInitDefaults.ml

@@ -127,6 +127,9 @@ module I = OpamFile.InitConfig
 
 let (@|) g f = OpamStd.Op.(g @* f) ()
 
+let switch_defaults =
+  OpamFile.SwitchDefaults.empty
+
 let init_config ?(sandboxing=true) () =
   I.empty |>
   I.with_repositories
@@ -137,4 +140,5 @@ let init_config ?(sandboxing=true) () =
   I.with_recommended_tools @| recommended_tools |>
   I.with_required_tools @| required_tools ~sandboxing |>
   I.with_init_scripts @| init_scripts |>
-  I.with_dl_tool @| dl_tool
+  I.with_dl_tool @| dl_tool |>
+  I.with_switch_defaults switch_defaults

src/client/opamInitDefaults.mli

@@ -21,6 +21,10 @@ val default_compiler: formula
 
 val eval_variables: (OpamVariable.t * string list * string) list
 
+(** Default switch defaults configuration file (also embedded in
+    {!init_config}). *)
+val switch_defaults: OpamFile.SwitchDefaults.t
+
 (** Default initial configuration file for use by [opam init] if nothing is
     supplied. *)
 val init_config: ?sandboxing:bool -> unit -> OpamFile.InitConfig.t

src/client/opamSwitchCommand.ml

@@ -270,7 +270,8 @@ let install_compiler_packages t atoms =
     (Success result);
   t
 
-let install gt ~rt ?synopsis ?repos ~update_config ~packages ?(local_compiler=false) switch =
+let install gt ~rt ?synopsis ?repos ~update_config ~packages ~switch_defaults
+                   ?(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
@@ -285,7 +286,53 @@ let install gt ~rt ?synopsis ?repos ~update_config ~packages ?(local_compiler=fa
   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" ->
+                  let f (package, _) =
+                    OpamPackage.Name.compare name package = 0
+                  in
+                  Some (B (List.exists f packages))
+              | _ ->
+                  None
+        in
+        let configure_switch conf =
+          let variables =
+            (* XXX Should be able to use description in the same way as for
+                   eval_variables *)
+            let f ((name, value, _description), filter) =
+              let eval = OpamFilter.eval_to_bool ~default:false env in
+              let expand = OpamFilter.expand_string (OpamPackageVar.resolve_global gt) in
+              if OpamStd.Option.map_default eval true filter then
+                let value =
+                  match value with
+                  | B _ ->
+                      value
+                  | S value ->
+                      S (expand value)
+                  | L values ->
+                      L (List.map expand values)
+                in
+                Some (name, value)
+              else
+                None
+            in
+            let switch_variables =
+              OpamFile.SwitchDefaults.switch_variables switch_defaults
+            in
+            OpamFile.Switch_config.(conf.variables)
+              @ OpamStd.List.filter_map f switch_variables
+          in
+          {conf with OpamFile.Switch_config.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

@@ -25,6 +25,7 @@ val install:
   ?repos:repository_name list ->
   update_config:bool ->
   packages:atom conjunction -> 
+  switch_defaults: OpamFile.SwitchDefaults.t ->
   ?local_compiler:bool ->
   switch ->
   unlocked global_state * rw switch_state

src/format/opamFile.ml

@@ -1209,6 +1209,69 @@ module Config = struct
   include SyntaxFile(ConfigSyntax)
 end
 
+module SwitchDefaultsSyntax = struct
+  let internal = "switch-defaults"
+
+  type t = {
+    opam_version : opam_version;
+    switch_variables :
+      ((variable * variable_contents * string) * filter option) list;
+  }
+
+  let opam_version t = t.opam_version
+  let switch_variables t = t.switch_variables
+
+  let with_opam_version opam_version t = {t with opam_version}
+  let with_switch_variables switch_variables t = {t with switch_variables}
+
+  let empty = {
+    opam_version = OpamVersion.current_nopatch;
+    switch_variables = [];
+  }
+
+  let fields =
+    [
+      "switch-variables", Pp.ppacc
+        with_switch_variables switch_variables
+        (Pp.V.map_list ~depth:2
+           (Pp.V.map_option
+              (Pp.V.map_triple
+                (Pp.V.ident -| Pp.of_module "variable" (module OpamVariable))
+                Pp.V.variable_contents
+                Pp.V.string)
+              (Pp.opt Pp.V.filter)));
+    ]
+
+  let pp_contents =
+    let name = internal in
+    Pp.I.fields ~name ~empty fields
+    -| Pp.I.show_errors ~name ~strict:true ()
+
+  let pp =
+    let name = internal in
+    let fields =
+      ("opam-version", Pp.ppacc
+        with_opam_version opam_version
+        (Pp.V.string
+          -| Pp.of_module "opam-version" (module OpamVersion));)::fields
+    in
+    Pp.I.map_file @@
+    Pp.I.fields ~name ~empty fields -|
+    Pp.I.show_errors ~name ~strict:true ()
+
+  let add t1 t2 =
+    let list = function [] -> fun l -> l | l -> fun _ -> l in
+    {
+      opam_version = t2.opam_version;
+      switch_variables = list t2.switch_variables t1.switch_variables;
+    }
+
+end
+module SwitchDefaults = struct
+  include SwitchDefaultsSyntax
+  include SyntaxFile(SwitchDefaultsSyntax)
+end
+
 module InitConfigSyntax = struct
   let internal = "init-config"
 
@@ -1228,6 +1291,7 @@ module InitConfigSyntax = struct
     recommended_tools : (string list * string option * filter option) list;
     required_tools : (string list * string option * filter option) list;
     init_scripts : ((string * string) * filter option) list;
+    switch_defaults : SwitchDefaults.t option;
   }
 
   let opam_version t = t.opam_version
@@ -1245,6 +1309,7 @@ module InitConfigSyntax = struct
   let recommended_tools t = t.recommended_tools
   let required_tools t = t.required_tools
   let init_scripts t = t.init_scripts
+  let switch_defaults t = t.switch_defaults
 
   let with_opam_version opam_version t = {t with opam_version}
   let with_repositories repositories t = {t with repositories}
@@ -1261,6 +1326,8 @@ module InitConfigSyntax = struct
   let with_recommended_tools recommended_tools t = {t with recommended_tools}
   let with_required_tools required_tools t = {t with required_tools}
   let with_init_scripts init_scripts t = {t with init_scripts}
+  let with_switch_defaults switch_defaults t =
+    {t with switch_defaults = Some switch_defaults}
 
   let criterion kind t =
     try Some (List.assoc kind t.solver_criteria)
@@ -1286,6 +1353,7 @@ module InitConfigSyntax = struct
     recommended_tools = [];
     required_tools = [];
     init_scripts = [];
+    switch_defaults = None;
   }
 
   let pp_repository_def =
@@ -1387,11 +1455,16 @@ module InitConfigSyntax = struct
       (fun (fld, ppacc) -> fld, Pp.embed with_wrappers wrappers ppacc)
       Wrappers.fields
 
+  let sections = [
+    "switch-defaults",
+    Pp.ppacc_opt with_switch_defaults switch_defaults
+      (Pp.I.anonymous_section SwitchDefaults.pp_contents);
+  ]
 
   let pp =
     let name = internal in
     Pp.I.map_file @@
-    Pp.I.fields ~name ~empty fields -|
+    Pp.I.fields ~name ~empty ~sections fields -|
     Pp.I.show_errors ~name ~strict:true ()
 
   let add t1 t2 =
@@ -1420,6 +1493,7 @@ module InitConfigSyntax = struct
       recommended_tools = list t2.recommended_tools t1.recommended_tools;
       required_tools = list t2.required_tools t1.required_tools;
       init_scripts = list t2.init_scripts t1.init_scripts;
+      switch_defaults = opt t2.switch_defaults t1.switch_defaults;
     }
 
 end