Generate .cargo/config

Cargo.toml

@@ -2,5 +2,5 @@
 members = [
   "rustler",
   "rustler_codegen",
-  "rustler_tests"
+  "rustler_tests/native/rustler_test",
 ]

rustler_mix/lib/mix/tasks/compile.rustler.ex

@@ -1,5 +1,6 @@
 defmodule Mix.Tasks.Compile.Rustler do
   use Mix.Task
+  require Logger
 
   alias Rustler.Compiler.{Messages, Rustup}
 
@@ -51,7 +52,7 @@ defmodule Mix.Tasks.Compile.Rustler do
       |> make_no_default_features_flag(Keyword.get(config, :default_features, true))
       |> make_features_flag(Keyword.get(config, :features, []))
       |> make_build_mode_flag(build_mode)
-      |> make_platform_hacks(output_type, :os.type())
+      |> make_platform_hacks(crate_full_path, output_type, :os.type())
 
     [cmd_bin | args] = compile_command
 
@@ -93,11 +94,44 @@ defmodule Mix.Tasks.Compile.Rustler do
     ["rustup", "run", version, "cargo", "rustc"]
   end
 
-  defp make_platform_hacks(args, :lib, {:unix, :darwin}) do
-    # Fix for https://github.com/hansihe/Rustler/issues/12
-    args ++ ["--", "--codegen", "link-args=-flat_namespace -undefined suppress"]
+  defp make_platform_hacks(args, crate_path, :lib, {:unix, :darwin}) do
+    path = Path.join([crate_path, ".cargo", "config"])
+
+    if File.exists?(path) do
+      args
+    else
+      IO.write([
+        "\n",
+        IO.ANSI.yellow(),
+        """
+        Compiling on macOS requires special link args in order to compile
+        correctly.
+
+        Rustler is currently working around this issue in the compiler task.
+        This will be removed in v1.0.0 in favor of a user supplied .cargo/config
+        file.
+
+        To remove this warning, please create #{path}
+        with the following content:
+
+              [target.x86_64-apple-darwin]
+              rustflags = [
+                  "-C", "link-arg=-undefined",
+                  "-C", "link-arg=dynamic_lookup",
+              ]
+
+        See https://developer.apple.com/library/archive/documentation/DeveloperTools/Conceptual/MachOTopics/1-Articles/executing_files.html
+        for more details.
+
+        """,
+        IO.ANSI.default_color(),
+        "\n"
+      ])
+
+      args ++ ["--", "-C", "link-arg=-undefined", "-C", "link-arg=dynamic_lookup"]
+    end
   end
-  defp make_platform_hacks(args, _, _), do: args
+  defp make_platform_hacks(args, _, _, _), do: args
 
   defp make_no_default_features_flag(args, true), do: args ++ []
   defp make_no_default_features_flag(args, false), do: args ++ ["--no-default-features"]

rustler_mix/lib/mix/tasks/rustler.new.ex

@@ -11,6 +11,7 @@ defmodule Mix.Tasks.Rustler.New do
   """
 
   @basic [
+    {:eex, "basic/.cargo/config", ".cargo/config"},
     {:eex, "basic/README.md", "README.md"},
     {:eex, "basic/Cargo.toml.eex", "Cargo.toml"},
     {:eex, "basic/src/lib.rs", "src/lib.rs"},

rustler_mix/priv/templates/basic/.cargo/config

@@ -0,0 +1,5 @@
+[target.x86_64-apple-darwin]
+rustflags = [
+    "-C", "link-arg=-undefined",
+    "-C", "link-arg=dynamic_lookup",
+]

rustler_tests/mix.exs

@@ -5,10 +5,10 @@ defmodule RustlerTest.Mixfile do
     [app: :rustler_test,
      version: "0.0.1",
      elixir: "~> 1.2",
-     build_embedded: Mix.env == :prod,
-     start_permanent: Mix.env == :prod,
-     compilers: [:rustler] ++ Mix.compilers,
-     rustler_crates: rustler_crates(),
+     build_embedded: Mix.env() == :prod,
+     start_permanent: Mix.env() == :prod,
+     compilers: [:rustler] ++ Mix.compilers(),
+     rustler_crates: [rustler_test: [mode: :debug]],
      deps: deps()]
   end
 
@@ -19,11 +19,4 @@ defmodule RustlerTest.Mixfile do
   defp deps do
     [{:rustler, path: "../rustler_mix"}]
   end
-
-  defp rustler_crates do
-    [rustler_test: [
-        path: ".",
-        mode: :debug,
-    ]]
-  end
 end

rustler_tests/Cargo.toml → rustler_tests/native/rustler_test/Cargo.toml

@@ -9,6 +9,6 @@ path = "src/lib.rs"
 crate-type = ["cdylib"]
 
 [dependencies]
-lazy_static = "1.0"
-rustler = { path = "../rustler" }
-rustler_codegen = { path = "../rustler_codegen" }
+lazy_static = "1.2"
+rustler = { path = "../../../rustler" }
+rustler_codegen = { path = "../../../rustler_codegen" }