feat(startup): Source runtime/plugin/**/*.lua at startup

For opt plugins these files are sourced on `:packadd`

* `:runtime` Now can exexute lua files

runtime/doc/repeat.txt

@@ -187,8 +187,10 @@ For writing a Vim script, see chapter 41 of the user manual |usr_41.txt|.
 
 							*:ru* *:runtime*
 :ru[ntime][!] [where] {file} ..
-			Read Ex commands from {file} in each directory given
-			by 'runtimepath' and/or 'packpath'.  There is no error
+			Source vim/lua {file} in each directory given by
+			'runtimepath' and/or 'packpath'. The vim files are
+			executed in same mannar as |:source| and lua files
+			similarly as |:luafile|. There is no error
 			for non-existing files.
 
 			Example: >
@@ -244,6 +246,8 @@ For writing a Vim script, see chapter 41 of the user manual |usr_41.txt|.
 			Note that {name} is the directory name, not the name
 			of the .vim file.  All the files matching the pattern
 				pack/*/opt/{name}/plugin/**/*.vim ~
+			and
+				pack/*/opt/{name}/plugin/**/*.lua ~
 			will be sourced.  This allows for using subdirectories
 			below "plugin", just like with plugins in
 			'runtimepath'.

runtime/doc/starting.txt

@@ -469,10 +469,15 @@ accordingly.  Vim proceeds in this order:
 7. Load the plugin scripts.					*load-plugins*
 	This does the same as the command: >
 		:runtime! plugin/**/*.vim
+		:runtime! plugin/**/*.lua
 <	The result is that all directories in the 'runtimepath' option will be
 	searched for the "plugin" sub-directory and all files ending in ".vim"
-	will be sourced (in alphabetical order per directory), also in
-	subdirectories.
+	and ".lua" will be sourced (in alphabetical order per directory),
+	also in subdirectories. First all the "*.vim" files will be sourced and
+	then all the "*.lua" files will be sourced. If two files with same
+	name but different extensions exists they will be treated in same
+	manner. For example when both "foo.vim" and "foo.lua" exists then
+	first "foo.vim" will be sourced then "foo.lua" will be ran.
 	However, directories in 'runtimepath' ending in "after" are skipped
 	here and only loaded after packages, see below.
 	Loading plugins won't be done when:

src/nvim/main.c

@@ -1367,7 +1367,8 @@ static void load_plugins(void)
 {
   if (p_lpl) {
     char_u *rtp_copy = NULL;
-    char_u *const plugin_pattern = (char_u *)"plugin/**/*.vim";  // NOLINT
+    char_u *const plugin_pattern_vim = (char_u *)"plugin/**/*.vim";  // NOLINT
+    char_u *const plugin_pattern_lua = (char_u *)"plugin/**/*.lua";  // NOLINT
 
     // First add all package directories to 'runtimepath', so that their
     // autoload directories can be found.  Only if not done already with a
@@ -1380,7 +1381,10 @@ static void load_plugins(void)
     }
 
     source_in_path(rtp_copy == NULL ? p_rtp : rtp_copy,
-                   plugin_pattern,
+                   plugin_pattern_vim,
+                   DIP_ALL | DIP_NOAFTER);
+    source_in_path(rtp_copy == NULL ? p_rtp : rtp_copy,
+                   plugin_pattern_lua,
                    DIP_ALL | DIP_NOAFTER);
     TIME_MSG("loading plugins");
     xfree(rtp_copy);
@@ -1392,7 +1396,8 @@ static void load_plugins(void)
     }
     TIME_MSG("loading packages");
 
-    source_runtime(plugin_pattern, DIP_ALL | DIP_AFTER);
+    source_runtime(plugin_pattern_vim, DIP_ALL | DIP_AFTER);
+    source_runtime(plugin_pattern_lua, DIP_ALL | DIP_AFTER);
     TIME_MSG("loading after plugins");
   }
 }

src/nvim/runtime.c

@@ -15,6 +15,7 @@
 #include "nvim/misc1.h"
 #include "nvim/os/os.h"
 #include "nvim/runtime.h"
+#include "nvim/lua/executor.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "runtime.c.generated.h"
@@ -49,7 +50,11 @@ void ex_runtime(exarg_T *eap)
 
 static void source_callback(char_u *fname, void *cookie)
 {
-  (void)do_source(fname, false, DOSO_NONE);
+  if (path_with_extension((const char *)fname, "lua")) {
+    nlua_exec_file((const char *)fname);
+  } else {
+    (void)do_source(fname, false, DOSO_NONE);
+  }
 }
 
 /// Find the file "name" in all directories in "path" and invoke
@@ -245,7 +250,8 @@ int source_in_path(char_u *path, char_u *name, int flags)
   return do_in_path_and_pp(path, name, flags, source_callback, NULL);
 }
 
-// Expand wildcards in "pat" and invoke do_source() for each match.
+// Expand wildcards in "pat" and invoke do_source()/nlua_exec_file()
+// for each match.
 static void source_all_matches(char_u *pat)
 {
   int num_files;
@@ -253,7 +259,11 @@ static void source_all_matches(char_u *pat)
 
   if (gen_expand_wildcards(1, &pat, &num_files, &files, EW_FILE) == OK) {
     for (int i = 0; i < num_files; i++) {
-      (void)do_source(files[i], false, DOSO_NONE);
+      if (path_with_extension((const char *)files[i], "lua")) {
+        nlua_exec_file((const char *)files[i]);
+      } else {
+        (void)do_source(files[i], false, DOSO_NONE);
+      }
     }
     FreeWild(num_files, files);
   }
@@ -405,17 +415,15 @@ theend:
 /// Load scripts in "plugin" and "ftdetect" directories of the package.
 static int load_pack_plugin(char_u *fname)
 {
-  static const char *plugpat = "%s/plugin/**/*.vim";  // NOLINT
   static const char *ftpat = "%s/ftdetect/*.vim";  // NOLINT
 
-  int retval = FAIL;
   char *const ffname = fix_fname((char *)fname);
   size_t len = strlen(ffname) + STRLEN(ftpat);
-  char_u *pat = try_malloc(len + 1);
-  if (pat == NULL) {
-    goto theend;
-  }
-  vim_snprintf((char *)pat, len, plugpat, ffname);
+  char_u *pat = xmallocz(len);
+
+  vim_snprintf((char *)pat, len, "%s/plugin/**/*.vim", ffname);
+  source_all_matches(pat);
+  vim_snprintf((char *)pat, len, "%s/plugin/**/*.lua", ffname);
   source_all_matches(pat);
 
   char_u *cmd = vim_strsave((char_u *)"g:did_load_filetypes");
@@ -430,12 +438,9 @@ static int load_pack_plugin(char_u *fname)
   }
   xfree(cmd);
   xfree(pat);
-  retval = OK;
-
-theend:
   xfree(ffname);
 
-  return retval;
+  return OK;
 }
 
 // used for "cookie" of add_pack_plugin()

test/functional/core/startup_spec.lua

@@ -11,6 +11,7 @@ local exec_lua = helpers.exec_lua
 local feed = helpers.feed
 local funcs = helpers.funcs
 local mkdir = helpers.mkdir
+local mkdir_p = helpers.mkdir_p
 local nvim_prog = helpers.nvim_prog
 local nvim_set = helpers.nvim_set
 local read_file = helpers.read_file
@@ -494,6 +495,53 @@ describe('user config init', function()
   end)
 end)
 
+describe('runtime/plugin', function()
+  local xhome = 'Xhome'
+  local pathsep = helpers.get_pathsep()
+  local xconfig = xhome .. pathsep .. 'Xconfig'
+
+  before_each(function()
+    mkdir_p(xconfig .. pathsep .. 'nvim')
+  end)
+
+  after_each(function()
+    rmdir(xhome)
+  end)
+
+  it('loads plugin/*.lua from XDG config home', function()
+    local plugin_folder_path = table.concat({xconfig, 'nvim', 'plugin'}, pathsep)
+    local plugin_file_path = table.concat({plugin_folder_path, 'plugin.lua'}, pathsep)
+    mkdir_p(plugin_folder_path)
+    write_file(plugin_file_path, [[
+    vim.g.lua_plugin = 1
+    ]])
+
+    clear{ args_rm={'-u' }, env={ XDG_CONFIG_HOME=xconfig }}
+
+    eq(1, eval('g:lua_plugin'))
+    rmdir(plugin_folder_path)
+  end)
+
+
+  it('loads plugin/*.lua from start plugins', function()
+    local plugin_path = table.concat({xconfig, 'nvim', 'pack', 'catagory',
+                                      'start', 'test_plugin'}, pathsep)
+    local plugin_folder_path = table.concat({plugin_path, 'plugin'}, pathsep)
+    local plugin_file_path = table.concat({plugin_folder_path, 'plugin.lua'},
+                                          pathsep)
+    mkdir_p(plugin_folder_path)
+    write_file(plugin_file_path, [[
+    vim.g.lua_plugin = 2
+    ]])
+
+    clear{ args_rm={'-u' }, env={ XDG_CONFIG_HOME=xconfig }}
+
+    eq(2, eval('g:lua_plugin'))
+    rmdir(plugin_path)
+  end)
+
+end)
+
 describe('user session', function()
   local xhome = 'Xhome'
   local pathsep = helpers.get_pathsep()

test/functional/helpers.lua

@@ -878,6 +878,11 @@ function module.os_kill(pid)
     or  'kill -9 '..pid..' > /dev/null'))
 end
 
+-- Create directories with non exsisting intermidiate directories
+function module.mkdir_p(path)
+  return module.meths.call_function('mkdir', {path, 'p'})
+end
+
 module = global_helpers.tbl_extend('error', module, global_helpers)
 
 return function(after_each)

test/functional/legacy/packadd_spec.lua

@@ -101,9 +101,14 @@ describe('packadd', function()
         call setline(1, 'let g:plugin_works = 24')
         wq
 
+        exe 'split ' . plugdir . '/plugin/test.lua'
+        call setline(1, 'vim.g.plugin_lua_works = 24')
+        wq
+
         packadd other
 
         call assert_equal(24, g:plugin_works)
+        call assert_equal(24, g:plugin_lua_works)
         call assert_true(len(&rtp) > len(rtp))
         call assert_match(Escape(plugdir) . '\($\|,\)', &rtp)
       endfunc
@@ -117,13 +122,18 @@ describe('packadd', function()
         exe 'split ' . s:plugdir . '/plugin/test.vim'
         call setline(1, 'let g:plugin_works = 42')
         wq
+        exe 'split ' . s:plugdir . '/plugin/test.lua'
+        call setline(1, 'let g:plugin_lua_works = 42')
+        wq
         let g:plugin_works = 0
+        let g:plugin_lua_works = 0
 
         packadd! mytest
 
         call assert_true(len(&rtp) > len(rtp))
         call assert_match(Escape(s:plugdir) . '\($\|,\)', &rtp)
         call assert_equal(0, g:plugin_works)
+        call assert_equal(0, g:plugin_lua_works)
 
         " check the path is not added twice
         let new_rtp = &rtp