Initialize env_node from Super_context.create

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>

src/super_context.ml

@@ -612,33 +612,40 @@ let create
     ; env = Hashtbl.create 128
     }
   in
+  let context_env_node = lazy (
+    let config =
+      match context.env_node with
+      | Some s -> s
+      | None -> { loc = Loc.none; rules = [] }
+    in
+    { Env_node.
+      dir = context.build_dir
+    ; inherit_from = None
+    ; scope = Scope.DB.find_by_dir scopes context.build_dir
+    ; config
+    ; ocaml_flags = None
+    }
+  ) in
   List.iter stanzas
     ~f:(fun { Dir_with_jbuild. ctx_dir; scope; stanzas; _ } ->
       List.iter stanzas ~f:(function
         | Env config ->
           let inherit_from =
             if ctx_dir = Scope.root scope then
-              None
+              context_env_node
             else
-              Some (lazy (Env.get t ~dir:(Path.parent_exn ctx_dir)))
+              lazy (Env.get t ~dir:(Path.parent_exn ctx_dir))
           in
           Hashtbl.add t.env ctx_dir
             { dir          = ctx_dir
-            ; inherit_from
+            ; inherit_from = Some inherit_from
             ; scope        = scope
             ; config       = config
             ; ocaml_flags  = None
             }
         | _ -> ()));
   if not (Hashtbl.mem t.env context.build_dir) then
-    Hashtbl.add t.env context.build_dir
-      { Env_node.
-        dir          = context.build_dir
-      ; inherit_from = None
-      ; scope        = Scope.DB.find_by_dir scopes context.build_dir
-      ; config       = { loc = Loc.none; rules = [] }
-      ; ocaml_flags  = None
-      };
+    Hashtbl.add t.env context.build_dir (Lazy.force context_env_node);
   t
 module Libs = struct
   open Build.O

test/blackbox-tests/test-cases/workspaces/run.t

@@ -47,3 +47,7 @@ see how we can set a "native" target. Which is the default.
   Entering directory 'targets-native'
   Entering directory 'targets-native'
   message from targets-native test
+
+Workspaces also allow you to set the env for a context:
+
+  $ dune printenv --root workspace-env --profile default

test/blackbox-tests/test-cases/workspaces/workspace-env/dune-project

@@ -0,0 +1 @@
+(lang dune 1.0)

test/blackbox-tests/test-cases/workspaces/workspace-env/dune-workspace

@@ -0,0 +1,7 @@
+(lang dune 1.0)
+
+(context
+ (default
+  (env
+   (default
+    (flags (:standard -machin))))))