Fix plugins lookup dir when Catala is installed to PATH

build_system/clerk_driver.ml

@@ -278,10 +278,7 @@ module Poll = struct
         Some root
       | _ -> None)
 
-  let exec_dir : File.t =
-    (* Do not use Sys.executable_name, which may resolve symlinks: we want the
-       original path. (e.g. _build/install/default/bin/foo is a symlink) *)
-    Filename.dirname Sys.argv.(0)
+  let exec_dir : File.t = Catala_utils.Cli.exec_dir
 
   let clerk_exe : File.t Lazy.t = lazy (Unix.realpath Sys.executable_name)
 

compiler/catala_utils/cli.ml

@@ -113,6 +113,15 @@ let file_lang filename =
          @{<yellow>%s@}, and @{<bold>--language@} was not specified"
         filename)
 
+let exec_dir =
+  let cmd = Sys.argv.(0) in
+  if String.contains cmd '/' then
+    (* Do not use Sys.executable_name, which may resolve symlinks: we want the
+       original path. (e.g. _build/install/default/bin/foo is a symlink) *)
+    Filename.dirname cmd
+  else (* searched in PATH *)
+    Filename.dirname Sys.executable_name
+
 let reverse_path ?(from_dir = Sys.getcwd ()) ~to_dir f =
   if Filename.is_relative from_dir then invalid_arg "File.with_reverse_path"
   else if not (Filename.is_relative f) then f
@@ -225,7 +234,6 @@ module Flags = struct
       let env = Cmd.Env.info "CATALA_PLUGINS" in
       let default =
         let ( / ) = Filename.concat in
-        let exec_dir = Filename.(dirname Sys.argv.(0)) in
         let dev_plugin_dir = exec_dir / "plugins" in
         if Sys.file_exists dev_plugin_dir then
           (* When running tests in place, may need to lookup in _build/default

compiler/catala_utils/cli.mli

@@ -154,3 +154,8 @@ val s_plugins : string
 exception Exit_with of int
 (** Exit with a specific exit code (but less brutally than [Sys.exit] which
     would bypass all finalisers) *)
+
+(** {2 Other helpers} *)
+
+val exec_dir : file
+(** Returns the directory of the currently running executable *)