Add the ability to point the typechecker at additional directories

fredemmott · fredemmott · commit 1574fa14e907 · 2018-05-24T11:36:00.000-07:00
Summary:
The intent here is to point at dependencies that should not be
modified. As such:
- they are not watched for changes
- if there is a duplicate definition, the one from `extra_paths` takes
  precedence as 'correct', in the same way that builtin HHIs take
  precedence over both 'extra' and ones  in the root.

There are two primary use cases:
- allow fbcode projects such as opensource/shipit/ to use the HSL and other libraries (probably via third-party2) without copying into the tree
- docs.hhvm.com: to reduce the amount of out-of-date documentation, all examples are unit tests - both for the typechecker, and the runtime.
  When typechecked, they need to be copied into a separate directory with nothing else (to make sure they're self-contained examples) - however,
  they need something like this to have access to the HSL.

Reviewed By: kmeht

Differential Revision: D8106266
diff --git a/hphp/hack/src/server/serverConfig.ml b/hphp/hack/src/server/serverConfig.ml
@@ -39,6 +39,8 @@ type t = {
   config_hash      : string option;
   (* A list of regexps for paths to ignore *)
   ignored_paths    : string list;
+  (* A list of extra paths to search for declarations *)
+  extra_paths      : Path.t list;
 }
 
 let filename = Relative_path.from_root ".hhconfig"
@@ -155,7 +157,6 @@ let process_ignored_paths config =
   SMap.get config "ignored_paths"
   |> Option.value_map ~f:convert_ignored_paths ~default:[]
 
-
 let maybe_relative_path fn =
   (* Note: this is not the same as calling realpath; the cwd is not
    * necessarily the same as hh_server's root!!! *)
@@ -165,6 +166,11 @@ let maybe_relative_path fn =
     else fn
   end
 
+let process_extra_paths config =
+  match SMap.get config "extra_paths" with
+  | Some s -> Str.split config_list_regexp s |> List.map ~f:maybe_relative_path
+  | _ -> []
+
 let extract_auto_namespace_element ns_map element =
   match element with
     | (source, Hh_json.JSON_String target) ->
@@ -195,6 +201,7 @@ let load config_filename options =
   let local_config = ServerLocalConfig.load ~silent:false in
   let version = SMap.get config "version" in
   let ignored_paths = process_ignored_paths config in
+  let extra_paths = process_extra_paths config in
   let load_script =
     Option.map (SMap.get config "load_script") maybe_relative_path in
   (* Since we use the unix alarm() for our timeouts, a timeout value of 0 means
@@ -236,6 +243,7 @@ let load config_filename options =
     formatter_override = formatter_override;
     config_hash = config_hash;
     ignored_paths = ignored_paths;
+    extra_paths = extra_paths;
   }, local_config
 
 (* useful in testing code *)
@@ -251,6 +259,7 @@ let default_config = {
   formatter_override = None;
   config_hash = None;
   ignored_paths = [];
+  extra_paths = [];
 }
 
 let set_parser_options config popt = { config with parser_options = popt }
@@ -263,3 +272,4 @@ let parser_options config = config.parser_options
 let formatter_override config = config.formatter_override
 let config_hash config = config.config_hash
 let ignored_paths config = config.ignored_paths
+let extra_paths config = config.extra_paths;
diff --git a/hphp/hack/src/server/serverConfig.mli b/hphp/hack/src/server/serverConfig.mli
@@ -18,6 +18,7 @@ val is_compatible : t -> t -> bool
 val default_config : t
 
 val ignored_paths       : t -> string list
+val extra_paths         : t -> Path.t list
 val gc_control          : t -> Gc.control
 val sharedmem_config    : t -> SharedMem.config
 val state_prefetcher_script : t -> Path.t option
diff --git a/hphp/hack/src/server/serverInit.ml b/hphp/hack/src/server/serverInit.ml
@@ -72,11 +72,26 @@ module ServerInitCommon = struct
       (List.map ~f:(Relative_path.(create Hhi)))
       (Find.make_next_files
          ~name:"hhi" ~filter:hhi_filter hhi_root) in
+    let rec concat_next_files l () =
+      begin match l with
+      | [] -> []
+      | hd::tl -> begin match hd () with
+        | [] -> concat_next_files tl ()
+        | x -> x
+        end
+      end
+    in
+    let extra_roots = ServerConfig.extra_paths genv.config in
+    let next_files_extra = List.map extra_roots
+      (fun root -> compose
+        (List.map ~f:Relative_path.create_detect_prefix)
+        (Find.make_next_files
+          ~filter:ServerEnv.file_filter
+          root)
+      ) |> concat_next_files
+    in
     fun () ->
-      let next = match next_files_hhi () with
-      | [] -> next_files_root ()
-      | x -> x
-      in
+      let next = concat_next_files [next_files_hhi; next_files_extra; next_files_root] () in
       Bucket.of_list next
 
   let with_loader_timeout timeout stage f =
