Make sure the action working directory exist

CHANGES.org

@@ -3,6 +3,8 @@
 - Added =${lib-available:<library-name>}= which expands to =true= or
  =false= with the same semantic as literals in =(select ...)= stanzas
 
+- Fix: make sure the action working directory exist before running it
+
 * 1.0+beta7 (12/04/2017)
 
 - Make the output quieter by default and add a =--verbose= argument

src/build_system.ml

@@ -294,7 +294,16 @@ let () =
     pending_targets := Pset.empty;
     Pset.iter fns ~f:Path.unlink_no_err)
 
-let make_local_dirs t paths ~map_path =
+let make_local_dir t path =
+  match Path.kind path with
+  | Local path ->
+    if not (Path.Local.Set.mem path t.local_mkdirs) then begin
+      Path.Local.mkdir_p path;
+      t.local_mkdirs <- Path.Local.Set.add path t.local_mkdirs
+    end
+  | _ -> ()
+
+let make_local_parent_dirs t paths ~map_path =
   Pset.iter paths ~f:(fun path ->
     match Path.kind (map_path path) with
     | Local path when not (Path.Local.is_root path) ->
@@ -336,7 +345,7 @@ let compile_rule t ~all_targets_by_dir ?(allow_override=false) pre_rule =
   end;
 
   let exec = Exec_status.Not_started (fun ~targeting ->
-    make_local_dirs t targets ~map_path:(fun x -> x);
+    make_local_parent_dirs t targets ~map_path:(fun x -> x);
     wait_for_deps t deps ~targeting
     >>= fun () ->
     let action, dyn_deps = Build_exec.exec t build () in
@@ -410,8 +419,8 @@ let compile_rule t ~all_targets_by_dir ?(allow_override=false) pre_rule =
             else
               path
           in
-          make_local_dirs t all_deps ~map_path:sandboxed;
-          make_local_dirs t targets  ~map_path:sandboxed;
+          make_local_parent_dirs t all_deps ~map_path:sandboxed;
+          make_local_parent_dirs t targets  ~map_path:sandboxed;
           Action.sandbox action
             ~sandboxed
             ~deps:all_deps_as_list
@@ -419,6 +428,7 @@ let compile_rule t ~all_targets_by_dir ?(allow_override=false) pre_rule =
         | None ->
           action
       in
+      make_local_dir t action.dir;
       Action.exec ~targets action >>| fun () ->
       Option.iter sandbox_dir ~f:Path.rm_rf;
       (* All went well, these targets are no longer pending *)