Merge pull request rescript-lang#4530 from chenglou/lastlast

Remove Unix dependency from syntax; sync up again

lib/4.06.1/whole_compiler.ml

@@ -427262,6 +427262,19 @@ Explanation: lists are singly-linked list, where a node contains a value and poi
 Solution: directly use `concat`."
 
   let variantIdent = "A polymorphic variant (e.g. #id) must start with an alphabetical letter."
+
+  let experimentalIfLet expr =
+    let switchExpr = {expr with Parsetree.pexp_attributes = []} in
+    Doc.concat [
+      Doc.text "If-let is currently highly experimental.";
+      Doc.line;
+      Doc.text "Use a regular `switch` with pattern matching instead:";
+      Doc.concat [
+        Doc.hardLine;
+        Doc.hardLine;
+        NapkinscriptPrinter.printExpression switchExpr (CommentTable.empty);
+      ]
+    ] |> Doc.toString ~width:80
 end
 
 
@@ -430226,7 +430239,13 @@ and parseIfOrIfLetExpression p =
   let expr = match p.Parser.token with
     | Let ->
       Parser.next p;
-      parseIfLetExpr startPos p
+      let ifLetExpr = parseIfLetExpr startPos p in
+      Parser.err
+        ~startPos:ifLetExpr.pexp_loc.loc_start
+        ~endPos:ifLetExpr.pexp_loc.loc_end
+        p
+        (Diagnostics.message (ErrorMessages.experimentalIfLet ifLetExpr));
+      ifLetExpr
     | _ ->
       parseIfExpr startPos p
   in
@@ -434293,8 +434312,8 @@ module Napkin_multi_printer : sig
 #1 "napkin_multi_printer.mli"
 (* Interface to print source code from different languages to res.
  * Takes a filename called "input" and returns the corresponding formatted res syntax *)
-val print: [`ml | `res | `refmt of string (* path to refmt *)] -> input: string -> string [@@live]
- 
+val print: [`ml | `res | `refmt of string (* path to refmt *)] -> input: string -> string
+
 end = struct
 #1 "napkin_multi_printer.ml"
 module IO = Napkin_io
@@ -434365,9 +434384,12 @@ let printMl ~isInterface ~filename =
 let printReason ~refmtPath ~isInterface ~filename =
   (* open a tempfile *)
   let (tempFilename, chan) =
+    (* refmt is just a prefix, `open_temp_file` takes care of providing a random name
+     * It tries 1000 times in the case of a name conflict.
+     * In practise this means that we shouldn't worry too much about filesystem races *)
     Filename.open_temp_file "refmt" (if isInterface then ".rei" else ".re") in
   close_out chan;
-  (* write the source code found in "filename" into the tempfile *)
+  (* Write the source code found in "filename" into the tempfile *)
   IO.writeFile ~filename:tempFilename ~content:(IO.readFile ~filename);
   let cmd = Printf.sprintf "%s --print=binary --in-place --interface=%b %s" refmtPath isInterface tempFilename in
   (* run refmt in-place in binary mode on the tempfile *)