From 926b0a742382e3062082350aab6b693d4fdf0a0d Mon Sep 17 00:00:00 2001
From: Dave Lucia <davelucianyc@gmail.com>
Date: Tue, 26 May 2026 20:42:05 -0400
Subject: [PATCH] fix(stdlib): convert dots to path separators in require()
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Lua 5.3 §6.3 requires that the module-name dots be replaced with the
directory separator before substitution into each `?` slot of a
`package.path` template. The new VM was substituting `modname` verbatim,
so `require("foo.bar")` looked for `foo.bar.lua` instead of `foo/bar.lua`.

This broke downstream consumers that chain dotted requires (e.g. the
`luassert` bootstrap: `luassert/init.lua` → `require("luassert.assert")`).

The fix hoists a `String.replace(modname, ".", "/")` above the pattern
loop. The default `package.path` already hardcodes `/` as the separator,
so no new configuration surface is introduced.

Adds a regression test exercising the disk-load path with a dotted name;
prior tests only used single-segment module names.
---
 lib/lua/vm/stdlib.ex                |  4 +++-
 test/lua/vm/stdlib/package_test.exs | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/lib/lua/vm/stdlib.ex b/lib/lua/vm/stdlib.ex
index 597f572..c9e99c5 100644
--- a/lib/lua/vm/stdlib.ex
+++ b/lib/lua/vm/stdlib.ex
@@ -750,8 +750,10 @@ defmodule Lua.VM.Stdlib do
 
   # Find a module file by searching the patterns
   defp find_module_file(modname, patterns) do
+    resolved = String.replace(modname, ".", "/")
+
     Enum.find_value(patterns, {:error, :not_found}, fn pattern ->
-      file_path = String.replace(pattern, "?", modname)
+      file_path = String.replace(pattern, "?", resolved)
 
       case File.read(file_path) do
         {:ok, content} -> {:ok, file_path, content}
diff --git a/test/lua/vm/stdlib/package_test.exs b/test/lua/vm/stdlib/package_test.exs
index 3486477..f0c815a 100644
--- a/test/lua/vm/stdlib/package_test.exs
+++ b/test/lua/vm/stdlib/package_test.exs
@@ -123,4 +123,22 @@ defmodule Lua.VM.Stdlib.PackageTest do
       assert {[true, 1], _} = eval_with_path(code, tmp_dir)
     end
   end
+
+  describe "dotted module names" do
+    @tag :tmp_dir
+    test "require('foo.bar') resolves dots to directory separators", %{tmp_dir: tmp_dir} do
+      File.mkdir_p!(Path.join(tmp_dir, "foo"))
+
+      File.write!(Path.join([tmp_dir, "foo", "bar.lua"]), """
+      return { ok = true }
+      """)
+
+      code = ~S"""
+      local m = require("foo.bar")
+      return m.ok
+      """
+
+      assert {[true], _} = eval_with_path(code, tmp_dir)
+    end
+  end
 end