Add dependencies only switch import

master_changes.md

@@ -34,6 +34,7 @@ users)
 ## Remove
 
 ## Switch
+  * ◈ Add `opam switch import --deps-only` option to install only dependencies of root package at import [#5388 @rjbou - fix #5200]
 
 ## Config
 
@@ -151,6 +152,7 @@ users)
 
 # API updates
 ## opam-client
+  * `OpamSwitchCommand.import`: add optional `?deps_only` argument to install only dependencies of root packages [#5388 @rjbou]
 
 ## opam-repository
  * `OpamRepository.fetch_from_cache`: when an archive is found, add a symlink (or copy) for the ones found in opam file but not in cache [#6068 @kit-ty-kate]

src/client/opamCommands.ml

@@ -2779,7 +2779,8 @@ let switch cli =
     mk_flag ~cli cli_original ["deps-only"]
       "When creating a local switch in a project directory (i.e. a directory \
        containing opam package definitions), install the dependencies of the \
-       project but not the project itself."
+       project but not the project itself. When importing a switch, do not \
+       install root packages."
   in
   let force =
     mk_flag ~cli (cli_from cli2_1) ["force"]
@@ -2997,7 +2998,7 @@ let switch cli =
               ~update_config:(not no_switch)
               switch
             @@ fun st ->
-            let st = OpamSwitchCommand.import st import_source in
+            let st = OpamSwitchCommand.import st ~deps_only import_source in
             let invariant = OpamSwitchState.infer_switch_invariant st in
             let st = OpamSwitchCommand.set_invariant_raw st invariant in
             st.switch_global, st
@@ -3011,7 +3012,8 @@ let switch cli =
           OpamConsole.warning
             "Switch exists, '--repositories' argument ignored";
         OpamSwitchState.with_ `Lock_write gt ~switch @@ fun st ->
-        OpamSwitchState.drop @@ OpamSwitchCommand.import st import_source
+        OpamSwitchState.drop
+        @@ OpamSwitchCommand.import st ~deps_only import_source
       end;
       `Ok ()
     | Some `remove, switches ->

src/client/opamSwitchCommand.ml

@@ -390,7 +390,7 @@ let switch_previous lock gt =
     OpamConsole.error_and_exit `Not_found
       "No previously used switch could be found"
 
-let import_t ?ask importfile t =
+let import_t ?ask ?(deps_only=false) importfile t =
   log "import switch";
 
   let extra_files = importfile.OpamFile.SwitchExport.extra_files in
@@ -462,6 +462,11 @@ let import_t ?ask importfile t =
       t.compiler_packages,
       import_sel.sel_installed -- import_sel.sel_compiler
   in
+  let to_install =
+    if deps_only then
+      to_install -- (import_sel.sel_roots -- import_sel.sel_compiler)
+    else to_install
+  in
 
   let t =
     { t with
@@ -679,7 +684,7 @@ let reinstall init_st =
              overlays = OpamPackage.Name.Map.empty; }
     st
 
-let import st filename =
+let import st ?deps_only filename =
   let import_str = match filename with
     | None   -> OpamSystem.string_of_channel stdin
     | Some f -> OpamFilename.read (OpamFile.filename f)
@@ -695,7 +700,7 @@ let import st filename =
           overlays = OpamPackage.Name.Map.empty }
       with e1 -> OpamStd.Exn.fatal e1; raise e
   in
-  import_t importfile st
+  import_t ?deps_only importfile st
 
 let set_invariant ?(force=false) st invariant =
   let satisfied = OpamFormula.satisfies_depends st.installed invariant in

src/client/opamSwitchCommand.mli

@@ -39,9 +39,11 @@ val install_compiler:
   ?additional_installs:atom list -> ?deps_only:bool -> ?ask:bool ->
   rw switch_state -> rw switch_state
 
-(** Import a file which contains the packages to install.  *)
+(** Import a file which contains the packages to install.
+    If [deps_only] is true do not install root packages. *)
 val import:
   rw switch_state ->
+  ?deps_only:bool ->
   OpamFile.SwitchExport.t OpamFile.t option ->
   rw switch_state
 

tests/reftests/switch-import.test

@@ -349,3 +349,49 @@ url {
 src: "file://${BASEDIR}/export-extra-files"
 }
 }
+### : import with deps-only :
+### <pkg:foo.1>
+opam-version: "2.0"
+flags: compiler
+### <pkg:foo.2>
+opam-version: "2.0"
+flags: compiler
+### <pkg:bar.1>
+opam-version: "2.0"
+depends: "baz"
+### <pkg:baz.1>
+opam-version: "2.0"
+### opam switch create for-deps foo.1
+
+<><> Installing new switch packages <><><><><><><><><><><><><><><><><><><><><><>
+Switch invariant: ["foo" {= "1"}]
+
+<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
+-> installed foo.1
+Done.
+### opam install bar
+The following actions will be performed:
+=== install 2 packages
+  - install bar 1
+  - install baz 1 [required by bar]
+
+<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
+-> installed baz.1
+-> installed bar.1
+Done.
+### opam switch export deps.xp
+### opam-cat deps.xp
+compiler: ["foo.1"]
+installed: ["bar.1" "baz.1" "foo.1"]
+opam-version: "2.0"
+roots: ["bar.1" "foo.1"]
+### opam switch import deps.xp --switch deps --deps-only
+The following actions will be performed:
+=== install 2 packages
+  - install baz 1
+  - install foo 1
+
+<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
+-> installed baz.1
+-> installed foo.1
+Done.