Skip directories when looking up programs in the PATH

Fixes #1616

Signed-off-by: Jeremie Dimino <jeremie@dimino.org>

CHANGES.md

@@ -4,6 +4,9 @@ unreleased
 - unstable-fmt: use boxes to wrap some lists (#1608, fix #1153, @emillon,
   thanks to @rgrinberg)
 
+- skip directories when looking up programs in the PATH (#1628, fixes
+  #1616, @diml)
+
 1.6.2 (05/12/2018)
 ------------------
 

src/stdune/bin.ml

@@ -18,13 +18,19 @@ let cons_path p ~_PATH =
 
 let exe = if Sys.win32 then ".exe" else ""
 
+let exists fn =
+  match Unix.stat (Path.to_string fn) with
+  | { st_kind = S_DIR; _ } -> false
+  | exception (Unix.Unix_error _) -> false
+  | _ -> true
+
 let best_prog dir prog =
   let fn = Path.relative dir (prog ^ ".opt" ^ exe) in
-  if Path.exists fn then
+  if exists fn then
     Some fn
   else
     let fn = Path.relative dir (prog ^ exe) in
-    if Path.exists fn then
+    if exists fn then
       Some fn
     else
       None

test/blackbox-tests/test-cases/github1616/run.t

@@ -1,3 +1,6 @@
 Regression test for #1616
 
   $ env PATH="$PWD/bin2:$PWD/bin1:$PATH" dune build --root root
+  Entering directory 'root'
+          prog alias default
+  Hello, World!