Some fixes to relative file lookups in modules and tests

This makes sure `catala module` finds the local runtime when run from the catala
source tree; and fixes lookup of the catala exec on custom uses of `clerk runtest`.

build_system/clerk_runtest.ml

@@ -197,7 +197,13 @@ let run_inline_tests
           let cmd_out_rd, cmd_out_wr = Unix.pipe () in
           let ic = Unix.in_channel_of_descr cmd_out_rd in
           let file_dir, file = Filename.dirname file, Filename.basename file in
-          let catala_exe = Unix.realpath catala_exe in
+          let catala_exe =
+            (* If the exe name contains directories, make it absolute. Otherwise
+               don't modify it so that it can be looked up in PATH. *)
+            if String.contains catala_exe Filename.dir_sep.[0] then
+              Unix.realpath catala_exe
+            else catala_exe
+          in
           let cmd =
             Array.of_list ((catala_exe :: catala_opts) @ test.params @ [file])
           in

compiler/plugins/modules.ml

@@ -84,24 +84,37 @@ let ocaml_libdir =
              "Could not locate the OCaml library directory, make sure OCaml or \
               opam is installed")))
 
+let rec find_catala_project_root dir =
+  if Sys.file_exists File.(dir / "catala.opam") then Some dir
+  else
+    let dir' = Unix.realpath File.(dir / Filename.parent_dir_name) in
+    if dir' = dir then None else find_catala_project_root dir'
+
 let runtime_dir =
   lazy
-    (match
-       List.find_map File.check_directory
-         [
-           "_build/install/default/lib/catala/runtime_ocaml";
-           (* Relative dir when running from catala source *)
-           File.(Lazy.force ocaml_libdir / "catala" / "runtime");
-         ]
-     with
-    | Some dir ->
-      Message.emit_debug "Catala runtime libraries found at @{<bold>%s@}." dir;
-      dir
-    | None ->
-      Message.raise_error
-        "Could not locate the Catala runtime library.@ Make sure that either \
-         catala is correctly installed,@ or you are running from the root of a \
-         compiled source tree.")
+    (let d =
+       match find_catala_project_root (Sys.getcwd ()) with
+       | Some root ->
+         (* Relative dir when running from catala source *)
+         File.(
+           root
+           / "_build"
+           / "install"
+           / "default"
+           / "lib"
+           / "catala"
+           / "runtime_ocaml")
+       | None -> File.(Lazy.force ocaml_libdir / "catala" / "runtime")
+     in
+     match File.check_directory d with
+     | Some dir ->
+       Message.emit_debug "Catala runtime libraries found at @{<bold>%s@}." dir;
+       dir
+     | None ->
+       Message.raise_error
+         "@[<hov>Could not locate the Catala runtime library.@ Make sure that \
+          either catala is correctly installed,@ or you are running from the \
+          root of a compiled source tree.@]")
 
 let compile options link_modules optimize check_invariants =
   let modname =

compiler/shared_ast/interpreter.ml

@@ -910,5 +910,10 @@ let load_runtime_modules = function
     List.iter
       Dynlink.(
         fun m ->
-          loadfile (adapt_filename (Filename.remove_extension m ^ ".cmo")))
+          try loadfile (adapt_filename (Filename.remove_extension m ^ ".cmo"))
+          with Dynlink.Error dl_err ->
+            Message.raise_error
+              "Could not load module %s, has it been suitably compiled?@;\
+               <1 2>@[<hov>%a@]" m Format.pp_print_text
+              (Dynlink.error_message dl_err))
       modules

compiler/shared_ast/print.ml

@@ -101,15 +101,6 @@ let external_ref fmt er =
   | External_value v -> TopdefName.format fmt v
   | External_scope s -> ScopeName.format fmt s
 
-let rec module_ctx ctx = function
-  | [] -> ctx
-  | (modname, mpos) :: path -> (
-    match ModuleName.Map.find_opt modname ctx.ctx_modules with
-    | None ->
-      Message.raise_spanned_error mpos "Module %a not found" ModuleName.format
-        modname
-    | Some ctx -> module_ctx ctx path)
-
 let rec typ_gen
     (ctx : decl_ctx option)
     ~(colors : Ocolor_types.color4 list)