Compiler: new -Werror flag to turn wanrings into errors (#1222)

* Compiler: new -Werror flag to turn wanrings into errors

* Changes

* Fix fmt

Author: hhugo

CHANGES.md

@@ -8,6 +8,7 @@
 * Compiler: be more consistent dealing with js vs ocaml strings (#984)
 * Compiler: Compiler: add BigInt to provided symbols (fix #1168) (#1191)
 * Compiler: use globalThis, drop joo_global_object #1193
+* Compiler: new -Werror flag to turn wanrings into errors (#1222)
 * Lib: add messageEvent to Dom_html (#1164)
 * Lib: add PerformanceObserver API (#1164)
 * Lib: add CSSStyleDeclaration.{setProperty, getPropertyValue, getPropertyPriority, removeProperty} (#1170)

compiler/bin-js_of_ocaml/js_of_ocaml.ml

@@ -45,17 +45,29 @@ let _ =
     | _ -> argv
   in
   try
-    Cmdliner.Term.eval_choice
-      ~catch:false
-      ~argv
-      Compile.command_main
-      [ Link.command
-      ; Build_fs.command
-      ; Build_runtime.command
-      ; Print_runtime.command
-      ; Check_runtime.command
-      ; Compile.command
-      ]
+    match
+      Cmdliner.Term.eval_choice
+        ~catch:false
+        ~argv
+        Compile.command_main
+        [ Link.command
+        ; Build_fs.command
+        ; Build_runtime.command
+        ; Print_runtime.command
+        ; Check_runtime.command
+        ; Compile.command
+        ]
+    with
+    | `Ok () | `Help | `Version ->
+        if !warnings > 0 && !werror
+        then (
+          Format.eprintf "%s: all warnings being treated as errors@." Sys.argv.(0);
+          exit 1)
+        else exit 0
+    | `Error `Term -> exit 1
+    | `Error `Parse -> exit 124
+    | `Error `Exn -> ()
+    (* should not happen *)
   with
   | (Match_failure _ | Assert_failure _ | Not_found) as exc ->
       let backtrace = Printexc.get_backtrace () in
@@ -65,7 +77,7 @@ let _ =
         Sys.argv.(0);
       Format.eprintf "Error: %s@." (Printexc.to_string exc);
       prerr_string backtrace;
-      exit 1
+      exit 125
   | Magic_number.Bad_magic_number s ->
       Format.eprintf "%s: Error: Not an ocaml bytecode file@." Sys.argv.(0);
       Format.eprintf "%s: Error: Invalid magic number %S@." Sys.argv.(0) s;

compiler/lib-cmdline/arg.ml

@@ -30,6 +30,7 @@ type t =
   { debug : string list on_off
   ; optim : string list on_off
   ; quiet : bool
+  ; werror : bool
   ; custom_header : string option
   }
 
@@ -73,6 +74,10 @@ let is_quiet =
   let doc = "suppress non-error messages." in
   Arg.(value & flag & info [ "quiet"; "q" ] ~doc)
 
+let is_werror =
+  let doc = "turn all warnings into errors." in
+  Arg.(value & flag & info [ "Werror" ] ~doc)
+
 let custom_header =
   let doc =
     "Provide a custom header for the generated JavaScript file, useful for making the \
@@ -82,7 +87,7 @@ let custom_header =
 
 let t =
   Term.(
-    pure (fun debug enable disable pretty debuginfo noinline quiet c_header ->
+    pure (fun debug enable disable pretty debuginfo noinline quiet werror c_header ->
         let enable = if pretty then "pretty" :: enable else enable in
         let enable = if debuginfo then "debuginfo" :: enable else enable in
         let disable = if noinline then "inline" :: disable else disable in
@@ -94,6 +99,7 @@ let t =
         { debug = { enable = debug; disable = [] }
         ; optim = { enable; disable }
         ; quiet
+        ; werror
         ; custom_header = c_header
         })
     $ debug
@@ -103,6 +109,7 @@ let t =
     $ debuginfo
     $ noinline
     $ is_quiet
+    $ is_werror
     $ custom_header)
 
 let on_off on off t =
@@ -112,4 +119,5 @@ let on_off on off t =
 let eval t =
   Config.Flag.(on_off enable disable t.optim);
   Debug.(on_off enable disable t.debug);
-  quiet := t.quiet
+  quiet := t.quiet;
+  werror := t.werror

compiler/lib-cmdline/arg.mli

@@ -26,6 +26,7 @@ type t =
   { debug : string list on_off
   ; optim : string list on_off
   ; quiet : bool
+  ; werror : bool
   ; custom_header : string option
   }
 

compiler/lib/stdlib.ml

@@ -66,7 +66,16 @@ include Int_replace_polymorphic_compare
 
 let quiet = ref false
 
-let warn fmt = Format.ksprintf (fun s -> if not !quiet then Format.eprintf "%s%!" s) fmt
+let werror = ref false
+
+let warnings = ref 0
+
+let warn fmt =
+  Format.ksprintf
+    (fun s ->
+      incr warnings;
+      if not !quiet then Format.eprintf "%s%!" s)
+    fmt
 
 let fail = ref true
 

toplevel/examples/lwt_toplevel/dune

@@ -87,6 +87,7 @@
  (action
   (run
    %{bin:js_of_ocaml}
+   --Werror
    -I
    %{lib:reactiveData:.}
    -I