feature: introduce public_headers

This field works like install_c_headers except it allows full file names
and allows to customize the destination paths

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

<!-- ps-id: cf542cda-1684-4719-bffd-fdb6a8bc2d63 -->

CHANGES.md

@@ -1,6 +1,10 @@
 Unreleased
 ----------
 
+- Introduce a `public_headers` field on libraries. This field is like
+  `install_c_headers`, but it allows to choose the extension and choose the
+  paths for the installed headers. (#7512, @rgrinberg)
+
 - Load the host context `findlib.conf` when cross-compiling (#7428, fixes
   #1701, @rgrinberg, @anmonteiro)
 

src/dune_rules/dune_file.ml

@@ -562,6 +562,7 @@ module Library = struct
     ; visibility : visibility
     ; synopsis : string option
     ; install_c_headers : string list
+    ; public_headers : Install_entry.File.t list
     ; ppx_runtime_libraries : (Loc.t * Lib_name.t) list
     ; modes : Mode_conf.Lib.Set.t
     ; kind : Lib_kind.t
@@ -599,6 +600,11 @@ module Library = struct
        and+ synopsis = field_o "synopsis" string
        and+ install_c_headers =
          field "install_c_headers" (repeat string) ~default:[]
+       and+ public_headers =
+         field "public_headers"
+           (Dune_lang.Syntax.since Stanza.syntax (3, 8)
+           >>> repeat Install_entry.File.decode)
+           ~default:[]
        and+ ppx_runtime_libraries =
          field "ppx_runtime_libraries"
            (repeat (located Lib_name.decode))
@@ -734,6 +740,7 @@ module Library = struct
        ; visibility
        ; synopsis
        ; install_c_headers
+       ; public_headers
        ; ppx_runtime_libraries
        ; modes
        ; kind

src/dune_rules/dune_file.mli

@@ -148,6 +148,7 @@ module Library : sig
     ; visibility : visibility
     ; synopsis : string option
     ; install_c_headers : string list
+    ; public_headers : Install_entry.File.t list
     ; ppx_runtime_libraries : (Loc.t * Lib_name.t) list
     ; modes : Mode_conf.Lib.Set.t
     ; kind : Lib_kind.t

src/dune_rules/install_rules.ml

@@ -95,14 +95,14 @@ end = struct
       && ctx.dynamically_linked_foreign_archives)
       (Lib_info.foreign_dll_files lib)
 
-  let lib_install_files sctx ~scope ~dir_contents ~dir ~sub_dir:lib_subdir
-      (lib : Library.t) =
+  let lib_install_files sctx ~expander ~scope ~dir_contents ~dir
+      ~sub_dir:lib_subdir (lib : Library.t) =
     let loc = lib.buildable.loc in
     let ctx = Super_context.context sctx in
     let lib_config = ctx.lib_config in
     let* info = Dune_file.Library.to_lib_info lib ~dir ~lib_config in
     let obj_dir = Lib_info.obj_dir info in
-    let make_entry section ?sub_dir ?dst fn =
+    let make_entry section ?(loc = loc) ?sub_dir ?dst fn =
       let entry =
         Install.Entry.make section fn ~kind:`File
           ~dst:
@@ -272,15 +272,25 @@ end = struct
       in
       modules
     in
+    let install_c_headers =
+      List.map lib.install_c_headers ~f:(fun base ->
+          Path.Build.relative dir (base ^ Foreign_language.header_extension))
+    in
     let* lib_files, dll_files =
       let+ lib_files = lib_files ~dir ~dir_contents ~lib_config info in
       let dll_files = dll_files ~modes:ocaml ~dynlink:lib.dynlink ~ctx info in
       (lib_files, dll_files)
     in
-    let+ execs = lib_ppxs ctx ~scope ~lib in
-    let install_c_headers =
-      List.map lib.install_c_headers ~f:(fun base ->
-          Path.Build.relative dir (base ^ Foreign_language.header_extension))
+    let* execs = lib_ppxs ctx ~scope ~lib in
+    let+ public_headers =
+      Install_entry.File.to_file_bindings_expanded lib.public_headers
+        ~expand_str:(Expander.No_deps.expand_str expander)
+        ~dir
+      >>| List.map ~f:(fun fb ->
+              let loc = File_binding.Expanded.src_loc fb in
+              let src = File_binding.Expanded.src fb in
+              let dst = File_binding.Expanded.dst fb in
+              make_entry ~loc Lib ?dst src)
     in
     List.concat
       [ sources
@@ -293,6 +303,7 @@ end = struct
             let entry = Install.Entry.make ~kind:`File Stublibs a in
             Install.Entry.Sourced.create ~loc entry)
       ; List.map ~f:(make_entry Lib) install_c_headers
+      ; public_headers
       ]
 
   let keep_if expander ~scope stanza =
@@ -402,7 +413,8 @@ end = struct
         | Library lib ->
           let sub_dir = Dune_file.Library.sub_dir lib in
           let* dir_contents = Dir_contents.get sctx ~dir in
-          lib_install_files sctx ~scope ~dir ~sub_dir lib ~dir_contents
+          lib_install_files sctx ~expander ~scope ~dir ~sub_dir lib
+            ~dir_contents
         | Coq_stanza.Theory.T coqlib ->
           Coq_rules.install_rules ~sctx ~dir coqlib
         | Documentation d ->

test/blackbox-tests/test-cases/foreign-stubs/public-headers.t

@@ -0,0 +1,47 @@
+Headers with the same filename cannot be installed together:
+
+  $ cat >dune-project <<EOF
+  > (lang dune 3.8)
+  > (package (name mypkg))
+  > EOF
+
+  $ mkdir inc
+
+  $ cat >dune <<EOF
+  > (library
+  >  (public_name mypkg)
+  >  (public_headers foo.h (inc/foo.h as inc/foo.h)))
+  > EOF
+
+  $ touch foo.h inc/foo.h
+
+  $ dune build mypkg.install && cat _build/default/mypkg.install | grep ".h"
+    "_build/install/default/lib/mypkg/foo.h"
+    "_build/install/default/lib/mypkg/inc/foo.h" {"inc/foo.h"}
+
+Now we try to use the installed headers:
+
+  $ dune install --prefix _install mypkg
+  $ export OCAMLPATH=$PWD/_install/lib:$OCAMLPATH
+
+  $ mkdir subdir
+  $ cd subdir
+
+  $ cat >dune-project <<EOF
+  > (lang dune 3.8)
+  > EOF
+
+  $ cat >dune <<EOF
+  > (executable
+  >  (name bar)
+  >  (foreign_stubs
+  >   (language c)
+  >   (include_dirs (lib mypkg))
+  >   (names foo)))
+  > EOF
+  $ touch bar.ml
+  $ cat >foo.c <<EOF
+  > #include <foo.h>
+  > #include <inc/foo.h>
+  > EOF
+  $ dune build bar.exe