fix(melange): treat private libraries with (package ..) as public libs

doc/changes/10415.md

@@ -0,0 +1,3 @@
+- melange: treat private libraries with `(package ..)` as public libraries,
+  fixing an issue where `import` paths were wrongly emitted. (#10415,
+  @anmonteiro)

src/dune_rules/cinaps.ml

@@ -183,6 +183,7 @@ let gen_rules sctx t ~dir ~scope =
       ~requires_link
       ~flags:(Ocaml_flags.of_list [ "-w"; "-24" ])
       ~js_of_ocaml:None
+      ~melange_package_name:None
       ~package:None
   in
   let* (_ : Exe.dep_graphs) =

src/dune_rules/compilation_context.ml

@@ -83,7 +83,7 @@ type t =
   ; sandbox : Sandbox_config.t
   ; package : Package.t option
   ; vimpl : Vimpl.t option
-  ; public_lib_name : Lib_name.t option
+  ; melange_package_name : Lib_name.t option
   ; modes : Lib_mode.Map.Set.t
   ; bin_annot : bool
   ; ocamldep_modules_data : Ocamldep.Modules_data.t
@@ -108,7 +108,7 @@ let js_of_ocaml t = t.js_of_ocaml
 let sandbox t = t.sandbox
 let set_sandbox t sandbox = { t with sandbox }
 let package t = t.package
-let public_lib_name t = t.public_lib_name
+let melange_package_name t = t.melange_package_name
 let vimpl t = t.vimpl
 let modes t = t.modes
 let bin_annot t = t.bin_annot
@@ -130,7 +130,7 @@ let create
   ?stdlib
   ~js_of_ocaml
   ~package
-  ?public_lib_name
+  ~melange_package_name
   ?vimpl
   ?modes
   ?bin_annot
@@ -197,7 +197,7 @@ let create
   ; sandbox
   ; package
   ; vimpl
-  ; public_lib_name
+  ; melange_package_name
   ; modes
   ; bin_annot
   ; ocamldep_modules_data

src/dune_rules/compilation_context.mli

@@ -32,7 +32,7 @@ val create
   -> ?stdlib:Ocaml_stdlib.t
   -> js_of_ocaml:Js_of_ocaml.In_context.t option
   -> package:Package.t option
-  -> ?public_lib_name:Lib_name.t
+  -> melange_package_name:Lib_name.t option
   -> ?vimpl:Vimpl.t
   -> ?modes:Mode_conf.Set.Details.t Lib_mode.Map.t
   -> ?bin_annot:bool
@@ -65,7 +65,7 @@ val sandbox : t -> Sandbox_config.t
 val set_sandbox : t -> Sandbox_config.t -> t
 val package : t -> Package.t option
 val vimpl : t -> Vimpl.t option
-val public_lib_name : t -> Lib_name.t option
+val melange_package_name : t -> Lib_name.t option
 val modes : t -> Lib_mode.Map.Set.t
 val for_wrapped_compat : t -> t
 val for_root_module : t -> Module.t -> t

src/dune_rules/exe_rules.ml

@@ -173,6 +173,7 @@ let executables_rules
       ~preprocessing:pp
       ~js_of_ocaml
       ~opaque:Inherit_from_settings
+      ~melange_package_name:None
       ~package:exes.package
   in
   let lib_config = ocaml.lib_config in

src/dune_rules/inline_tests.ml

@@ -167,6 +167,7 @@ include Sub_system.Register_end_point (struct
           ~requires_link:(Memo.lazy_ (fun () -> runner_libs))
           ~flags
           ~js_of_ocaml:(Some js_of_ocaml)
+          ~melange_package_name:None
           ~package
       in
       let linkages =

src/dune_rules/lib_rules.ml

@@ -528,14 +528,16 @@ let cctx (lib : Library.t) ~sctx ~source_modules ~dir ~expander ~scope ~compile_
   in
   let package = Library.package lib in
   let js_of_ocaml = Js_of_ocaml.In_context.make ~dir lib.buildable.js_of_ocaml in
-  (* XXX(anmonteiro): `public_lib_name` is used to derive Melange's
+  (* XXX(anmonteiro): `melange_package_name` is used to derive Melange's
      `--bs-package-name` argument. We only use the library name for public
-     libraries because we need melange to preserve relative paths for private
-     libs (i.e. not pass the `--bs-package-name` arg). *)
-  let public_lib_name =
+     libraries / private libraries with `(package ..)` because we need Melange
+     to preserve relative paths for private libs (i.e. not pass the
+     `--bs-package-name` arg). *)
+  let melange_package_name =
     match lib.visibility with
     | Public p -> Some (Public_lib.name p)
-    | Private _ -> None
+    | Private (Some pkg) -> Some (Lib_name.mangled (Package.name pkg) (snd lib.name))
+    | Private None -> None
   in
   Compilation_context.create
     ()
@@ -552,7 +554,7 @@ let cctx (lib : Library.t) ~sctx ~source_modules ~dir ~expander ~scope ~compile_
     ?stdlib:lib.stdlib
     ~package
     ?vimpl
-    ?public_lib_name
+    ~melange_package_name
     ~modes
 ;;
 

src/dune_rules/mdx.ml

@@ -488,6 +488,7 @@ let mdx_prog_gen t ~sctx ~dir ~scope ~mdx_prog =
       ~requires_link
       ~opaque:(Explicit false)
       ~js_of_ocaml:None
+      ~melange_package_name:None
       ~package:None
       ()
   in

src/dune_rules/melange/melange_rules.ml

@@ -1,17 +1,24 @@
 open Import
 open Memo.O
 
-let output_of_lib ~target_dir lib =
-  let info = Lib.info lib in
-  match Lib_info.status info with
-  | Private _ -> `Private_library_or_emit target_dir
-  | Installed | Installed_private | Public _ ->
-    let lib_name = Lib_info.name info in
-    let src_dir = Lib_info.src_dir info in
+let output_of_lib =
+  let public_lib ~info ~target_dir lib_name =
     `Public_library
-      ( src_dir
+      ( Lib_info.src_dir info
       , Path.Build.L.relative target_dir [ "node_modules"; Lib_name.to_string lib_name ]
       )
+  in
+  fun ~target_dir lib ->
+    let info = Lib.info lib in
+    match Lib_info.status info with
+    | Private (_, None) -> `Private_library_or_emit target_dir
+    | Private (_, Some pkg) ->
+      public_lib
+        ~info
+        ~target_dir
+        (Lib_name.mangled (Package.name pkg) (Lib_name.to_local_exn (Lib.name lib)))
+    | Installed | Installed_private | Public _ ->
+      public_lib ~info ~target_dir (Lib_info.name info)
 ;;
 
 let lib_output_path ~output_dir ~lib_dir src =
@@ -298,6 +305,7 @@ let setup_emit_cmj_rules
         ~preprocessing:pp
         ~js_of_ocaml:None
         ~opaque:Inherit_from_settings
+        ~melange_package_name:None
         ~package:mel.package
         ~modes:
           { ocaml = { byte = None; native = None }; melange = Some (Requested mel.loc) }

src/dune_rules/module_compilation.ml

@@ -55,7 +55,7 @@ let melange_args (cctx : Compilation_context.t) (cm_kind : Lib_mode.Cm_kind.t) m
       let package_output =
         Module.file ~ml_kind:Impl module_ |> Option.value_exn |> Path.parent_exn
       in
-      match Compilation_context.public_lib_name cctx with
+      match Compilation_context.melange_package_name cctx with
       | None -> [], package_output
       | Some lib_name ->
         let dir =

src/dune_rules/ppx_driver.ml

@@ -327,6 +327,7 @@ let build_ppx_driver sctx ~scope ~target ~pps ~pp_names =
       ~requires_link
       ~opaque
       ~js_of_ocaml:None
+      ~melange_package_name:None
       ~package:None
       ~bin_annot:false
       ()

src/dune_rules/toplevel.ml

@@ -238,6 +238,7 @@ module Stanza = struct
         ~requires_link
         ~flags
         ~js_of_ocaml:None
+        ~melange_package_name:None
         ~package:None
         ~preprocessing
     in

src/dune_rules/utop.ml

@@ -192,6 +192,7 @@ let setup sctx ~dir =
       ~requires_compile:requires
       ~flags
       ~js_of_ocaml:None
+      ~melange_package_name:None
       ~package:None
       ~preprocessing
   in

test/blackbox-tests/test-cases/melange/emit-private.t

@@ -2,7 +2,7 @@ Test dependency on a private library in the same package as melange.emit
 
   $ cat >dune-project <<EOF
   > (lang dune 3.8)
-  > (package  (name a))
+  > (package  (name pkg))
   > (using melange 0.1)
   > EOF
 
@@ -12,7 +12,7 @@ Test dependency on a private library in the same package as melange.emit
   > (library
   >  (name a)
   >  (modes melange)
-  >  (package a))
+  >  (package pkg))
   > EOF
 
   $ cat > a/foo.ml <<EOF
@@ -22,33 +22,33 @@ Test dependency on a private library in the same package as melange.emit
   $ dune build
 
   $ dune install --prefix $PWD/prefix --display short
-  Installing $TESTCASE_ROOT/prefix/lib/a/META
-  Installing $TESTCASE_ROOT/prefix/lib/a/__private__/a/a.ml
-  Installing $TESTCASE_ROOT/prefix/lib/a/__private__/a/foo.ml
-  Installing $TESTCASE_ROOT/prefix/lib/a/__private__/a/melange/.public_cmi_melange/a.cmi
-  Installing $TESTCASE_ROOT/prefix/lib/a/__private__/a/melange/.public_cmi_melange/a.cmt
-  Installing $TESTCASE_ROOT/prefix/lib/a/__private__/a/melange/.public_cmi_melange/a__Foo.cmi
-  Installing $TESTCASE_ROOT/prefix/lib/a/__private__/a/melange/.public_cmi_melange/a__Foo.cmt
-  Installing $TESTCASE_ROOT/prefix/lib/a/__private__/a/melange/a.cmj
-  Installing $TESTCASE_ROOT/prefix/lib/a/__private__/a/melange/a__Foo.cmj
-  Installing $TESTCASE_ROOT/prefix/lib/a/dune-package
+  Installing $TESTCASE_ROOT/prefix/lib/pkg/META
+  Installing $TESTCASE_ROOT/prefix/lib/pkg/__private__/a/a.ml
+  Installing $TESTCASE_ROOT/prefix/lib/pkg/__private__/a/foo.ml
+  Installing $TESTCASE_ROOT/prefix/lib/pkg/__private__/a/melange/.public_cmi_melange/a.cmi
+  Installing $TESTCASE_ROOT/prefix/lib/pkg/__private__/a/melange/.public_cmi_melange/a.cmt
+  Installing $TESTCASE_ROOT/prefix/lib/pkg/__private__/a/melange/.public_cmi_melange/a__Foo.cmi
+  Installing $TESTCASE_ROOT/prefix/lib/pkg/__private__/a/melange/.public_cmi_melange/a__Foo.cmt
+  Installing $TESTCASE_ROOT/prefix/lib/pkg/__private__/a/melange/a.cmj
+  Installing $TESTCASE_ROOT/prefix/lib/pkg/__private__/a/melange/a__Foo.cmj
+  Installing $TESTCASE_ROOT/prefix/lib/pkg/dune-package
 
   $ cat > b/dune <<EOF
   > (melange.emit
   >  (target dist)
   >  (alias dist)
   >  (libraries a)
   >  (emit_stdlib false)
-  >  (package a))
+  >  (package pkg))
   > EOF
 
   $ cat > b/bar.ml <<EOF
   > let x = Js.log A.Foo.x
   > EOF
 
   $ OCAMLPATH=$PWD/prefix/lib/:$OCAMLPATH dune build @dist --display=short 2>&1 | grep -v melange
-          melc b/dist/a/a.js
-          melc b/dist/a/foo.js
+          melc b/dist/node_modules/pkg.__private__.a/a.js
+          melc b/dist/node_modules/pkg.__private__.a/foo.js
           melc b/dist/b/bar.js
 
   $ node _build/default/b/dist/b/bar.js

test/blackbox-tests/test-cases/melange/private-lib-dep.t

@@ -41,14 +41,14 @@ Melange public library depends on private library
 
   $ dune build @melange
 
-  $ node _build/default/output/entry.js 2>&1 | grep 'Cannot find module'
-  Error: Cannot find module 'priv/priv.js'
+  $ node _build/default/output/entry.js
+  public lib uses private
 
   $ cat _build/default/output/node_modules/foo/foo.js
   // Generated by Melange
   'use strict';
 
-  let Priv = require("priv/priv.js");
+  let Priv = require("foo.__private__.priv/priv.js");
 
   const x = "public lib uses " + Priv.x;