Fix a bug with warning 199 and -stop-after typing

ocaml/driver/compile_common.ml

@@ -139,9 +139,10 @@ let implementation ~hook_parse_tree ~hook_typed_tree info ~backend =
       let typed = typecheck_impl info parsed in
       hook_typed_tree typed;
       if Clflags.(should_stop_after Compiler_pass.Typing) then () else begin
-        backend info typed
+        backend info typed;
       end;
     end;
-    Builtin_attributes.warn_unchecked_property ();
+    if not (Clflags.(should_stop_after Compiler_pass.Selection)) then
+      Builtin_attributes.warn_unchecked_property ();
     Warnings.check_fatal ();
   )

tests/backend/checkmach/dune.inc

@@ -850,3 +850,10 @@
  (enabled_if (= %{context_name} "main"))
  (deps test_arity.output test_arity.output.corrected)
  (action (diff test_arity.output test_arity.output.corrected)))
+
+(rule
+ (alias runtest)
+ (deps stop_after_typing.ml)
+ (target stop_after_typing.cmi)
+ (enabled_if (= %{context_name} "main"))
+ (action (run %{bin:ocamlopt.opt} stop_after_typing.ml -g -c -stop-after typing -O3 -warn-error +a)))

tests/backend/checkmach/gen/gen_dune.ml

@@ -18,6 +18,24 @@ let () =
  ${enabled_if}
  (deps ${deps})
  (action (run %{bin:ocamlopt.opt} %{deps} -g -c ${extra_flags} -dcse -dcheckmach -dump-into-file -O3 -warn-error +a)))
+|};
+    Buffer.output_buffer Out_channel.stdout buf
+  in
+  let print_cmi_target name =
+    let subst = function
+      | "enabled_if" -> enabled_if
+      | "name" -> name
+      | _ -> "assert false"
+    in
+    Buffer.clear buf;
+    Buffer.add_substitute buf subst
+    {|
+(rule
+ (alias runtest)
+ (deps ${name}.ml)
+ (target ${name}.cmi)
+ ${enabled_if}
+ (action (run %{bin:ocamlopt.opt} ${name}.ml -g -c -stop-after typing -O3 -warn-error +a)))
 |};
     Buffer.output_buffer Out_channel.stdout buf
   in
@@ -140,4 +158,5 @@ let () =
     ~extra_dep:None ~exit_code:2 "test_all_opt3";
   print_test_expected_output ~cutoff:default_cutoff
     ~extra_dep:None ~exit_code:2 "test_arity";
+  print_cmi_target "stop_after_typing";
   ()

tests/backend/checkmach/stop_after_typing.ml

@@ -0,0 +1,4 @@
+(* This just checks we don't get a warning 199 (unchecked zero alloc attribute)
+   if we stop after typing. *)
+
+let[@zero_alloc] f x = x