feat: dune build asks for relocking (#10851)

* feat: ask to re run dune pkg lock on change

Signed-off-by: Etienne Marais <[email protected]>

src/dune_pkg/package_universe.ml

@@ -127,6 +127,27 @@ let check_for_unnecessary_packges_in_lock_dir
       ])
 ;;
 
+let up_to_date local_packages (lock_dir : Lock_dir.t) =
+  let local_packages =
+    Package_name.Map.values local_packages |> List.map ~f:Local_package.for_solver
+  in
+  let non_local_dependencies =
+    Local_package.For_solver.list_non_local_dependency_set local_packages
+  in
+  let dependency_hash = Local_package.Dependency_set.hash non_local_dependencies in
+  match lock_dir.dependency_hash, dependency_hash with
+  | None, None -> `Valid
+  | Some (_, lock_dir_dependency_hash), Some non_local_dependencies_hash
+    when Local_package.Dependency_hash.equal
+           lock_dir_dependency_hash
+           non_local_dependencies_hash -> `Valid
+  | None, Some _ ->
+    `Valid (* This case happens when the user writes themselves their lock.dune. *)
+  | Some _, Some non_local_dependencies_hash ->
+    `Invalid (Some non_local_dependencies_hash)
+  | Some _, None -> `Invalid None
+;;
+
 let validate_dependency_hash { local_packages; lock_dir; _ } =
   let local_packages =
     Package_name.Map.values local_packages |> List.map ~f:Local_package.for_solver

src/dune_pkg/package_universe.mli

@@ -10,6 +10,14 @@ val create
   -> Lock_dir.t
   -> (t, User_message.t) result
 
+(** Verifies if the dependencies described in the project file are still
+    synchronize with the dependencies selected in the lock directroy. If it is
+    not the case, it returns the hash of the new dependency set. *)
+val up_to_date
+  :  Local_package.t Package_name.Map.t
+  -> Lock_dir.t
+  -> [ `Valid | `Invalid of Local_package.Dependency_hash.t option ]
+
 (** Returns the dependencies of the specified package within the package
     universe *)
 val opam_package_dependencies_of_package

src/dune_rules/gen_rules.ml

@@ -656,6 +656,30 @@ let private_context ~dir components _ctx =
     Gen_rules.make ~build_dir_only_sub_dirs (Memo.return Rules.empty)
 ;;
 
+let raise_on_lock_dir_out_of_sync =
+  Per_context.create_by_name ~name:"check-lock-dir" (fun ctx ->
+    Memo.lazy_ (fun () ->
+      let open Memo.O in
+      let* lock_dir_available = Lock_dir.lock_dir_active ctx in
+      if lock_dir_available
+      then
+        let* lock_dir = Lock_dir.get_exn ctx in
+        let+ local_packages =
+          Dune_load.packages ()
+          >>| Dune_lang.Package.Name.Map.map ~f:Dune_pkg.Local_package.of_package
+        in
+        match Dune_pkg.Package_universe.up_to_date local_packages lock_dir with
+        | `Valid -> ()
+        | `Invalid _ ->
+          let hints = Pp.[ text "run dune pkg lock" ] in
+          User_error.raise
+            ~hints
+            [ Pp.text "The lock dir is not sync with your dune-project" ]
+      else Memo.return ())
+    |> Memo.Lazy.force)
+  |> Staged.unstage
+;;
+
 let gen_rules ctx ~dir components =
   if Context_name.equal ctx Install.Context.install_context.name
   then (
@@ -684,5 +708,7 @@ let gen_rules ctx ~dir components =
   then private_context ~dir components ctx
   else if Context_name.equal ctx Fetch_rules.context.name
   then Fetch_rules.gen_rules ~dir ~components
-  else gen_rules ctx (Super_context.find_exn ctx) ~dir components
+  else
+    let* () = raise_on_lock_dir_out_of_sync ctx in
+    gen_rules ctx (Super_context.find_exn ctx) ~dir components
 ;;

test/blackbox-tests/test-cases/pkg/lock-out-of-sync.t

@@ -0,0 +1,54 @@
+Trying to build a package after updating the dependencies in dune-project but
+without running `dune pkg lock` must raise an error in the context of Dune
+Package Managemenet. 
+
+  $ . ./helpers.sh
+
+Create a fake project and lock it:
+
+  $ mkrepo
+  $ mkpkg foo <<EOF
+  > build: [ "echo" "foo" ]
+  > EOF
+  $ mkpkg bar <<EOF
+  > build: [ "echo" "bar" ]
+  > EOF
+
+  $ cat > dune-project <<EOF
+  > (lang dune 3.16)
+  > (package
+  >  (name test)
+  >  (allow_empty)
+  >  (depends foo))
+  > EOF
+  $ add_mock_repo_if_needed
+  $ dune pkg lock
+  Solution for dune.lock:
+  - foo.0.0.1
+
+As the lock file is syncronised with `dune-pkg`, the build succeeds:
+  $ dune build
+  foo
+
+We add the bar dependency to the test package
+  $ cat > dune-project <<EOF
+  > (lang dune 3.16)
+  > (package
+  >  (name test)
+  >  (allow_empty)
+  >  (depends foo bar))
+  > EOF
+
+It fails as we have not regenerated the lock:
+  $ dune build
+  Error: The lock dir is not sync with your dune-project
+  Hint: run dune pkg lock
+  [1]
+
+We fix it and the build succeeds again:
+  $ dune pkg lock
+  Solution for dune.lock:
+  - bar.0.0.1
+  - foo.0.0.1
+  $ dune build
+  bar