fix: correctly generate .install files

Previously, the contents of the .install file would depend on whether
the .opam install file would be present in the source.

This check is wrong whenever we generate the .opam file ourselves. This
commit checks if we are generating the .opam file.

Signed-off-by: Rudi Grinberg <[email protected]>

<!-- ps-id: ce2222c8-7d98-418a-9345-340bdaa32baf -->

src/dune_rules/dune_project.ml

@@ -730,7 +730,7 @@ let forbid_opam_files_relative_to_project opam_file_location packages =
         ]
 
 let parse_packages (name : Name.t option) ~info ~dir ~version packages
-    opam_file_location opam_packages =
+    opam_file_location ~generate_opam_files opam_packages =
   let open Memo.O in
   let+ packages =
     forbid_opam_files_relative_to_project opam_file_location opam_packages;
@@ -799,18 +799,26 @@ let parse_packages (name : Name.t option) ~info ~dir ~version packages
       | Ok packages -> (
         Memo.return
         @@
+        let generated_opam_file =
+          if generate_opam_files then fun p ->
+            { p with Package.has_opam_file = Generated }
+          else Fun.id
+        in
         match opam_file_location with
         | `Inside_opam_directory ->
           Package.Name.Map.map packages ~f:(fun p ->
               let dir = Path.Source.relative dir "opam" in
-              Package.set_inside_opam_dir p ~dir)
+              let p = Package.set_inside_opam_dir p ~dir in
+              generated_opam_file p)
         | `Relative_to_project ->
           Package.Name.Map.merge packages opam_packages
             ~f:(fun _name dune opam ->
               match (dune, opam) with
-              | _, None -> dune
+              | None, None -> assert false
+              | Some p, None -> Some (generated_opam_file p)
               | Some p, Some _ ->
-                Some { p with Package.has_opam_file = Exists true }
+                let p = { p with Package.has_opam_file = Exists true } in
+                Some (generated_opam_file p)
               | None, Some (loc, _) ->
                 User_error.raise ~loc
                   [ Pp.text
@@ -907,10 +915,13 @@ let parse ~dir ~(lang : Lang.Instance.t) ~file =
          Option.value opam_file_location
            ~default:(opam_file_location_default ~lang)
        in
+       let generate_opam_files =
+         Option.value ~default:false generate_opam_files
+       in
        let open Memo.O in
        let+ packages =
          parse_packages name ~info ~dir ~version packages opam_file_location
-           opam_packages
+           ~generate_opam_files opam_packages
        in
        let name =
          match name with
@@ -945,9 +956,6 @@ let parse ~dir ~(lang : Lang.Instance.t) ~file =
        let explicit_js_mode =
          Option.value explicit_js_mode ~default:(explicit_js_mode_default ~lang)
        in
-       let generate_opam_files =
-         Option.value ~default:false generate_opam_files
-       in
        let use_standard_c_and_cxx_flags =
          match use_standard_c_and_cxx_flags with
          | None -> use_standard_c_and_cxx_flags_default ~lang

src/dune_rules/install_rules.ml

@@ -10,16 +10,14 @@ let install_file ~(package : Package.Name.t) ~findlib_toolchain =
 
 module Package_paths = struct
   let opam_file (ctx : Context.t) (pkg : Package.t) =
-    match pkg.has_opam_file with
-    | Exists false -> Memo.return None
-    | Exists true ->
-      Memo.return
-      @@ Some (Path.Build.append_source ctx.build_dir (Package.opam_file pkg))
-    | Look_inside_opam_dir -> (
-      let opam_file = Package.opam_file pkg in
-      Source_tree.file_exists opam_file >>| function
-      | true -> Some (Path.Build.append_source ctx.build_dir opam_file)
-      | false -> None)
+    let opam_file = Package.opam_file pkg in
+    let exists =
+      match pkg.has_opam_file with
+      | Exists b -> b
+      | Generated -> true
+    in
+    if exists then Some (Path.Build.append_source ctx.build_dir opam_file)
+    else None
 
   let meta_file (ctx : Context.t) pkg =
     Path.Build.append_source ctx.build_dir (Package.meta_file pkg)
@@ -419,7 +417,7 @@ end = struct
     let+ init =
       Package.Name.Map_traversals.parallel_map packages
         ~f:(fun _name (pkg : Package.t) ->
-          let* opam_file = Package_paths.opam_file ctx pkg in
+          let opam_file = Package_paths.opam_file ctx pkg in
           let init =
             let file section local_file dst =
               Install.Entry.make section local_file ~kind:`File ~dst

src/dune_rules/package.ml

@@ -549,7 +549,7 @@ end
 
 type opam_file =
   | Exists of bool
-  | Look_inside_opam_dir
+  | Generated
 
 type t =
   { id : Id.t
@@ -579,10 +579,7 @@ let name t = t.id.name
 let dir t = t.id.dir
 
 let set_inside_opam_dir t ~dir =
-  { t with
-    has_opam_file = Look_inside_opam_dir
-  ; opam_file = Path.Source.relative dir (Name.opam_fn t.id.name)
-  }
+  { t with opam_file = Path.Source.relative dir (Name.opam_fn t.id.name) }
 
 let encode (name : Name.t)
     { id = _
@@ -687,7 +684,7 @@ let dyn_of_opam_file =
   let open Dyn in
   function
   | Exists b -> variant "Exists" [ bool b ]
-  | Look_inside_opam_dir -> variant "Look_inside_opam_dir" []
+  | Generated -> variant "Generated" []
 
 let to_dyn
     { id

src/dune_rules/package.mli

@@ -142,7 +142,7 @@ end
 
 type opam_file =
   | Exists of bool
-  | Look_inside_opam_dir
+  | Generated
 
 type t =
   { id : Id.t

test/blackbox-tests/test-cases/dune-project-meta/fresh-build.t

@@ -16,7 +16,7 @@ source tree if (generate_opam_files true) is enabled.
 
   $ dune build foo.install
   $ grep opam _build/default/foo.install
-  [1]
+    "_build/install/default/lib/foo/opam"
 
   $ dune build @check
   $ dune build foo.install