fix(runtime): don't use regexes inside lua require'mod'

Fixes #15147 and fixes #15497. Also sketch "subdir" caching. Currently
this only caches whether an rtp entry has a "lua/" subdir but we could
consider cache other subdirs potentially or even "lua/mybigplugin/"
possibly.

Note: the async_leftpad test doesn't actually fail on master, at least
not deterministically (even when disabling the fast_breakcheck
throttling). It's still useful as a regression test for further changes
and included as such.

2 files changed, 22 insertions, 21 deletions

diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 3f93bb9a09..59ebafd9c8 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -790,7 +790,7 @@ int nlua_call(lua_State *lstate)
   Error err = ERROR_INIT;
   size_t name_len;
   const char_u *name = (const char_u *)luaL_checklstring(lstate, 1, &name_len);
-  if (!nlua_is_deferred_safe(lstate)) {
+  if (!nlua_is_deferred_safe()) {
     return luaL_error(lstate, e_luv_api_disabled, "vimL function");
   }
 
@@ -846,7 +846,7 @@ free_vim_args:
 
 static int nlua_rpcrequest(lua_State *lstate)
 {
-  if (!nlua_is_deferred_safe(lstate)) {
+  if (!nlua_is_deferred_safe()) {
     return luaL_error(lstate, e_luv_api_disabled, "rpcrequest");
   }
   return nlua_rpc(lstate, true);
@@ -1316,7 +1316,7 @@ Object nlua_call_ref(LuaRef ref, const char *name, Array args, bool retval, Erro
 
 /// check if the current execution context is safe for calling deferred API
 /// methods. Luv callbacks are unsafe as they are called inside the uv loop.
-bool nlua_is_deferred_safe(lua_State *lstate)
+bool nlua_is_deferred_safe(void)
 {
   return in_fast_callback == 0;
 }
diff --git a/src/nvim/lua/vim.lua b/src/nvim/lua/vim.lua
index 5ca4cc82a5..51b7430957 100644
--- a/src/nvim/lua/vim.lua
+++ b/src/nvim/lua/vim.lua
@@ -57,28 +57,29 @@ end
 function vim._load_package(name)
   local basename = name:gsub('%.', '/')
   local paths = {"lua/"..basename..".lua", "lua/"..basename.."/init.lua"}
-  for _,path in ipairs(paths) do
-    local found = vim.api.nvim_get_runtime_file(path, false)
-    if #found > 0 then
-      local f, err = loadfile(found[1])
-      return f or error(err)
-    end
+  local found = vim.api.nvim__get_runtime(paths, false, {is_lua=true})
+  if #found > 0 then
+    local f, err = loadfile(found[1])
+    return f or error(err)
   end
 
+  local so_paths = {}
   for _,trail in ipairs(vim._so_trails) do
     local path = "lua"..trail:gsub('?', basename) -- so_trails contains a leading slash
-    local found = vim.api.nvim_get_runtime_file(path, false)
-    if #found > 0 then
-      -- Making function name in Lua 5.1 (see src/loadlib.c:mkfuncname) is
-      -- a) strip prefix up to and including the first dash, if any
-      -- b) replace all dots by underscores
-      -- c) prepend "luaopen_"
-      -- So "foo-bar.baz" should result in "luaopen_bar_baz"
-      local dash = name:find("-", 1, true)
-      local modname = dash and name:sub(dash + 1) or name
-      local f, err = package.loadlib(found[1], "luaopen_"..modname:gsub("%.", "_"))
-      return f or error(err)
-    end
+    table.insert(so_paths, path)
+  end
+
+  found = vim.api.nvim__get_runtime(so_paths, false, {is_lua=true})
+  if #found > 0 then
+    -- Making function name in Lua 5.1 (see src/loadlib.c:mkfuncname) is
+    -- a) strip prefix up to and including the first dash, if any
+    -- b) replace all dots by underscores
+    -- c) prepend "luaopen_"
+    -- So "foo-bar.baz" should result in "luaopen_bar_baz"
+    local dash = name:find("-", 1, true)
+    local modname = dash and name:sub(dash + 1) or name
+    local f, err = package.loadlib(found[1], "luaopen_"..modname:gsub("%.", "_"))
+    return f or error(err)
   end
   return nil
 end