add an install alias

bin/main.ml

@@ -135,6 +135,11 @@ type target =
   | File  of Path.t
   | Alias of Path.t * Alias.t
 
+let aliases_in_source_tree =
+  String_set.of_list
+    [ "install"
+    ]
+
 let resolve_targets (setup : Main.setup) user_targets =
   match user_targets with
   | [] -> []
@@ -147,14 +152,15 @@ let resolve_targets (setup : Main.setup) user_targets =
           if Path.is_root path then
             die "@ on the command line must be followed by a valid alias name"
           else
+            let name = Path.basename path in
             let path =
-              if Path.is_in_build_dir path then
+              if Path.is_in_build_dir path ||
+                 String_set.mem name aliases_in_source_tree then
                 path
               else
                 Path.append setup.context.build_dir path
             in
             let dir = Path.parent path in
-            let name = Path.basename path in
             Alias (path, Alias.make ~dir name)
         else
           File (

doc/manual.org

@@ -130,7 +130,16 @@ Jbuilder doesn't read =<package>.opam= files, however when a
 =<package>.opam= is present, Jbuilder will knows that the package
 named =<package>= exists. It will know how to construct a
 =<package>.install= file in the same directory, to handle installation
-via [[https://opam.ocaml.org/][opam]].
+via [[https://opam.ocaml.org/][opam]]. In addition, Jbuilder will also know how to build
+=<package>.install= at the root of the workspace, for
+convenience. Jbuilder also defines the =install= alias, which depends
+on all the buildable =<package>.install= at the root of the
+workspace. So for instance to build everything that is installable in
+a workspace, run:
+
+#+begin_src
+$ jbuilder build @install
+#+end_src
 
 Declaring a package this way will allow you to add elements such as
 libraries, executables, documentations, ... to your package by

src/gen_rules.ml

@@ -1658,13 +1658,25 @@ module Gen(P : Params) = struct
     install_file package_path package)
 
   let () =
-    if Path.basename ctx.build_dir = "default" then
-      String_map.iter P.packages ~f:(fun ~key:pkg ~data:path ->
-        let install_file = Path.relative path (pkg ^ ".install") in
-        add_rule
-          (Build.copy
-             ~src:(Path.append ctx.build_dir install_file)
-             ~dst:install_file))
+    let install_alias = Alias.make ~dir:ctx.build_dir "install" in
+    let global_install_alias = Alias.make ~dir:Path.root "install" in
+    let is_default = Path.basename ctx.build_dir = "default" in
+    String_map.iter P.packages ~f:(fun ~key:pkg ~data:path ->
+      let install_fn = pkg ^ ".install" in
+      let in_source_dir = Path.relative path install_fn in
+      let orig = Path.append ctx.build_dir in_source_dir in
+      let at_root_of_build_context = Path.relative ctx.build_dir install_fn in
+      if not (Path.is_root path) then
+        add_rule (Build.copy ~src:orig ~dst:at_root_of_build_context);
+      Alias.add_deps install_alias [at_root_of_build_context];
+
+      if is_default then begin
+        add_rule (Build.copy ~src:orig ~dst:in_source_dir);
+        let at_root = Path.relative Path.root install_fn in
+        if not (Path.is_root path) then
+          add_rule (Build.copy ~src:orig ~dst:at_root);
+        Alias.add_deps global_install_alias [at_root]
+      end)
 end
 
 let gen ~context ~file_tree ~tree ~stanzas ~packages

src/path.ml

@@ -80,7 +80,7 @@ module Local = struct
     | t ->
       let len = String.length t in
       match String.rindex_from t (len - 1) '/' with
-      | exception Not_found -> ""
+      | exception Not_found -> t
       | i -> String.sub t ~pos:(i + 1) ~len:(len - i - 1)
 
   let relative initial_t path =