Add link flags ocamlmklib when using ctypes stubs.

doc/changes/8784.md

@@ -0,0 +1 @@
+- Add link flags to to ocamlmklib for ctypes stubs (#8784, @frejsoya)

src/dune_rules/lib_rules.ml

@@ -328,7 +328,14 @@ let build_stubs lib ~cctx ~dir ~expander ~requires ~dir_contents ~vlib_stubs_o_f
       | _ -> Action_builder.return []
     in
     let c_library_flags =
-      Expander.expand_and_eval_set expander lib.c_library_flags ~standard
+      let open Action_builder.O in
+      let+ c_lib = Expander.expand_and_eval_set expander lib.c_library_flags ~standard
+      and+ ctypes_lib =
+        (* CR rgrinberg: Should we add these flags to :standard? to make
+           it possible for users to remove these *)
+        Ctypes_rules.ctypes_cclib_flags sctx ~expander ~buildable:lib.buildable
+      in
+      c_lib @ ctypes_lib
     in
     let lib_o_files_for_all_modes = Mode.Map.Multi.for_all_modes o_files in
     let for_all_modes = List.rev_append vlib_stubs_o_files lib_o_files_for_all_modes in

test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/dune

@@ -0,0 +1,4 @@
+(executable
+ (name example)
+ (modes byte)
+ (libraries examplelib))

test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/dune-project

@@ -0,0 +1,3 @@
+(lang dune 3.10)
+
+(using ctypes 0.3)

test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/example.ml

@@ -0,0 +1,2 @@
+let () =
+  Printf.printf "%d\n" (Examplelib.C.Functions.add2 2)

test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/run.t

@@ -0,0 +1,23 @@
+Build an example library as a DLL and set up the environment so that it looks
+like a system/distro library that can be probed with pkg-config and dynamically
+loaded.
+
+  $ LIBEX=$(realpath "$PWD/../libexample")
+
+ocamlrun + requires CAML_LD_LIBRARY_PATH such that dlopen system call can find
+dllexamplelib_stub.so
+
+Explictly set {DYLD,LD}_LIBRARY_PATH at runtime for this testcase, otherwise
+dlopen cannot find libexample, after loading dllexamplelib_stub.so
+
+  $  PKG_CONFIG_PATH="$LIBEX/pkgconfig" PKG_CONFIG_ARGN="--define-prefix" DYLD_LIBRARY_PATH="$DYLD_LIBRARY_PATH:$LIBEX" LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$LIBEX" CAML_LD_LIBRARY_PATH="$CAML_LD_LIBRARY_PATH:$PWD/_build/default/stubgen" dune exec ./example.bc
+  4
+
+Utop works with ctypes pkg-config external library.
+
+  $   DYLD_LIBRARY_PATH="$DYLD_LIBRARY_PATH:$LIBEX" LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$LIBEX"  PKG_CONFIG_PATH="$LIBEX/pkgconfig" PKG_CONFIG_ARGN="--define-prefix" dune utop --display=short ./ -- example.ml
+    pkg-config stubgen/.pkg-config/libexample.cflags
+    pkg-config stubgen/.pkg-config/libexample.libs
+        ocamlc .utop/.utop.eobjs/byte/dune__exe__Utop.{cmi,cmo,cmt}
+        ocamlc .utop/utop.bc
+  4

test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/dune

@@ -0,0 +1,14 @@
+(library
+  (name examplelib)
+  (flags (:standard -w -9-27))
+  (ctypes
+    (external_library_name libexample)
+    (build_flags_resolver pkg_config)
+    (headers (include "example.h"))
+    (type_description
+      (instance Types)
+      (functor Type_description))
+    (function_description
+      (instance Functions)
+      (functor Function_description))
+    (generated_entry_point C)))

test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/function_description.ml

@@ -0,0 +1,8 @@
+open Ctypes
+
+module Types = Types_generated
+
+module Functions (F : Ctypes.FOREIGN) = struct
+  open F
+  let add2 = foreign "example_add2" (int @-> returning int)
+end

test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/type_description.ml

@@ -0,0 +1,3 @@
+module Types (F : Ctypes.TYPE) = struct
+
+end

test/blackbox-tests/test-cases/ctypes/dune

@@ -27,6 +27,7 @@
 
 (cram
  (applies_to
+  bytecode-stubs-external-lib
   lib-pkg_config
   lib-pkg_config-multiple-fd
   lib-external-name-need-mangling