From e7dbaeb8ce8c3156664b8763b676a544ad417b7a Mon Sep 17 00:00:00 2001
From: Leo White <leo@lpw25.net>
Date: Mon, 26 Oct 2020 12:39:43 +0000
Subject: [PATCH] Fix reproducibility for `-no-alias-deps`

---
 .../reproducibility/cmis_on_file_system.ml    |  6 ++--
 typing/env.ml                                 | 34 +++++++++++++------
 2 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/testsuite/tests/reproducibility/cmis_on_file_system.ml b/testsuite/tests/reproducibility/cmis_on_file_system.ml
index b9761dfca..92066e711 100644
--- a/testsuite/tests/reproducibility/cmis_on_file_system.ml
+++ b/testsuite/tests/reproducibility/cmis_on_file_system.ml
@@ -4,7 +4,7 @@
   ** ocamlc.byte
   compile_only = "true"
   module = "cmis_on_file_system.ml"
-  flags="-bin-annot"
+  flags="-bin-annot -no-alias-deps -w '-49'"
   *** script
   script= "mv cmis_on_file_system.cmt lone.cmt"
   **** ocamlc.byte
@@ -12,7 +12,7 @@
   compile_only="true"
   ***** ocamlc.byte
   compile_only = "true"
-  flags="-bin-annot"
+  flags="-bin-annot -no-alias-deps -w '-49'"
   module="cmis_on_file_system.ml"
   ****** compare-binary-files
   program="cmis_on_file_system.cmt"
@@ -24,3 +24,5 @@
     at a given point in time *)
 type t = int
 let () = ()
+
+module M = Cmis_on_file_system_companion
diff --git a/typing/env.ml b/typing/env.ml
index 1f35e0d10..108bb71ab 100644
--- a/typing/env.ml
+++ b/typing/env.ml
@@ -707,20 +707,34 @@ let find_name_module ~mark name tbl =
 
 let add_persistent_structure id env =
   if not (Ident.persistent id) then invalid_arg "Env.add_persistent_structure";
-  if not (Current_unit_name.is_ident id) then
-    let summary =
+  if Current_unit_name.is_ident id then env
+  else begin
+    let material =
+      (* This addition only observably changes the environment if it shadows a
+         non-persistent module already in the environment.
+         (See PR#9345) *)
       match
         IdTbl.find_name wrap_module ~mark:false (Ident.name id) env.modules
       with
-      | exception Not_found | _, Mod_persistent -> env.summary
-      | _ -> Env_persistent (env.summary, id)
+      | exception Not_found | _, Mod_persistent -> false
+      | _ -> true
     in
-    { env with
-      modules = IdTbl.add id Mod_persistent env.modules;
-      summary
-    }
-  else
-    env
+    let summary =
+      if material then Env_persistent (env.summary, id)
+      else env.summary
+    in
+    let modules =
+      (* With [-no-alias-deps], non-material additions should not
+         affect the environment at all. We should only observe the
+         existence of a cmi when accessing components of the module.
+         (See #9991). *)
+      if material || not !Clflags.transparent_modules then
+        IdTbl.add id Mod_persistent env.modules
+      else
+        env.modules
+    in
+    { env with modules; summary }
+  end
 
 let components_of_module ~alerts ~uid env fs ps path addr mty =
   {