Hint for mistyped targets

CHANGES.org

@@ -2,6 +2,9 @@
 
 - Add support for building Reason projects (Rudi Grinberg, #58)
 
+- Hint for mistyped targets. Only suggest correction on the basename
+  for now, otherwise it's slow when the workspace is big
+
 * 1.0+beta8 (17/04/2017)
 
 - Added =${lib-available:<library-name>}= which expands to =true= or

bin/main.ml

@@ -287,6 +287,31 @@ type target =
   | File  of Path.t
   | Alias of Path.t * Alias.t
 
+let target_hint (setup : Main.setup) path =
+  assert (Path.is_local path);
+  let sub_dir = Path.parent path in
+  let candidates = Build_system.all_targets setup.build_system in
+  let candidates =
+    if Path.is_in_build_dir path then
+      candidates
+    else
+      List.map candidates ~f:(fun path ->
+        match Path.extract_build_context path with
+        | None -> path
+        | Some (_, path) -> path)
+  in
+  let candidates =
+    (* Only suggest hints for the basename, otherwise it's slow when there are lots of
+       files *)
+    List.filter_map candidates ~f:(fun path ->
+      if Path.parent path = sub_dir then
+        Some (Path.to_string path)
+      else
+        None)
+  in
+  let candidates = String_set.of_list candidates |> String_set.elements in
+  hint (Path.to_string path) candidates
+
 let resolve_targets ~log common (setup : Main.setup) user_targets =
   match user_targets with
   | [] -> []
@@ -305,7 +330,8 @@ let resolve_targets ~log common (setup : Main.setup) user_targets =
         else
           let path = Path.relative Path.root (prefix_target common s) in
           let can't_build path =
-            die "Don't know how to build %s" (Path.to_string path)
+            die "Don't know how to build %s%s" (Path.to_string path)
+              (target_hint setup path)
           in
           if not (Path.is_local path) then
             [File path]

src/build_system.ml

@@ -64,6 +64,9 @@ type t =
   ; mutable local_mkdirs : Path.Local.Set.t
   }
 
+
+let all_targets t = Hashtbl.fold t.files ~init:[] ~f:(fun ~key ~data:_ acc -> key :: acc)
+
 let timestamp t fn =
   match Hashtbl.find t.timestamps fn with
   | Some _ as x -> x

src/build_system.mli

@@ -33,3 +33,6 @@ val all_lib_deps : t -> Path.t list -> Build.lib_deps Path.Map.t
 (** Return all the library dependencies required to build these targets, by context
     name *)
 val all_lib_deps_by_context : t -> Path.t list -> Build.lib_deps String_map.t
+
+(** List of all buildable targets *)
+val all_targets : t -> Path.t list