fix(exrc): exrc knows its own location #34638

Problem:
'exrc' files are inherently bound to their location / workspace and
therefore require to "know" their location on the filesystem. However,
currently using `debug.getinfo(1, 'S')` returns `"<nvim>"`.

Solution:
Include the filepath as chunkname in `loadstring()` and `nlua_exec()`.

(cherry picked from commit f7c939fa7a)

runtime/doc/options.txt

@@ -2357,6 +2357,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	in the |trust| list. Use |:trust| to manage trusted files. See also
 	|vim.secure.read()|.
 
+	To get its own location, Lua exrc files can use |debug.getinfo()|.
+
 	Compare 'exrc' to |editorconfig|:
 	- 'exrc' can execute any code; editorconfig only specifies settings.
 	- 'exrc' is Nvim-specific; editorconfig works in other editors.

runtime/doc/vimfn.txt

@@ -2040,7 +2040,8 @@ expand({string} [, {nosuf} [, {list}]])                               *expand()*
 			<SID>		"<SNR>123_"  where "123" is the
 					current script ID  |<SID>|
 			<script>	sourced script file, or script file
-					where the current function was defined
+					where the current function was defined.
+					Use |debug.getinfo()| in Lua scripts.
 			<stack>		call stack
 			<cword>		word under the cursor
 			<cWORD>		WORD under the cursor

runtime/lua/vim/_meta/options.lua

@@ -2015,6 +2015,8 @@ vim.bo.et = vim.bo.expandtab
 --- in the `trust` list. Use `:trust` to manage trusted files. See also
 --- `vim.secure.read()`.
 ---
+--- To get its own location, Lua exrc files can use `debug.getinfo()`.
+---
 --- Compare 'exrc' to `editorconfig`:
 --- - 'exrc' can execute any code; editorconfig only specifies settings.
 --- - 'exrc' is Nvim-specific; editorconfig works in other editors.

runtime/lua/vim/_meta/vimfn.lua

@@ -1801,7 +1801,8 @@ function vim.fn.exp(expr) end
 ---   <SID>    "<SNR>123_"  where "123" is the
 ---       current script ID  |<SID>|
 ---   <script>  sourced script file, or script file
----       where the current function was defined
+---       where the current function was defined.
+---       Use |debug.getinfo()| in Lua scripts.
 ---   <stack>    call stack
 ---   <cword>    word under the cursor
 ---   <cWORD>    WORD under the cursor

src/nvim/api/deprecated.c

@@ -62,7 +62,7 @@ Object nvim_execute_lua(String code, Array args, Arena *arena, Error *err)
   FUNC_API_DEPRECATED_SINCE(7)
   FUNC_API_REMOTE_ONLY
 {
-  return nlua_exec(code, args, kRetObject, arena, err);
+  return nlua_exec(code, NULL, args, kRetObject, arena, err);
 }
 
 /// Gets the buffer number

src/nvim/api/vim.c

@@ -514,7 +514,7 @@ Object nvim_exec_lua(String code, Array args, Arena *arena, Error *err)
   FUNC_API_REMOTE_ONLY
 {
   // TODO(bfredl): convert directly from msgpack to lua and then back again
-  return nlua_exec(code, args, kRetObject, arena, err);
+  return nlua_exec(code, NULL, args, kRetObject, arena, err);
 }
 
 /// Calculates the number of display cells occupied by `text`.

src/nvim/eval.lua

@@ -2342,7 +2342,8 @@ M.funcs = {
       	<SID>		"<SNR>123_"  where "123" is the
       			current script ID  |<SID>|
       	<script>	sourced script file, or script file
-      			where the current function was defined
+      			where the current function was defined.
+      			Use |debug.getinfo()| in Lua scripts.
       	<stack>		call stack
       	<cword>		word under the cursor
       	<cWORD>		WORD under the cursor

src/nvim/lua/executor.c

@@ -1507,17 +1507,20 @@ int typval_exec_lua_callable(LuaRef lua_cb, int argcount, typval_T *argvars, typ
 /// Used for nvim_exec_lua() and internally to execute a lua string.
 ///
 /// @param[in]  str  String to execute.
+/// @param[in]  chunkname Chunkname, defaults to "<nvim>".
 /// @param[in]  args array of ... args
 /// @param[in]  mode Whether and how the the return value should be converted to Object
 /// @param[in] arena  can be NULL, then nested allocations are used
 /// @param[out]  err  Location where error will be saved.
 ///
 /// @return Return value of the execution.
-Object nlua_exec(const String str, const Array args, LuaRetMode mode, Arena *arena, Error *err)
+Object nlua_exec(const String str, const char *chunkname, const Array args, LuaRetMode mode,
+                 Arena *arena, Error *err)
 {
   lua_State *const lstate = global_lstate;
 
-  if (luaL_loadbuffer(lstate, str.data, str.size, "<nvim>")) {
+  const char *name = (chunkname && chunkname[0]) ? chunkname : "<nvim>";
+  if (luaL_loadbuffer(lstate, str.data, str.size, name)) {
     size_t len;
     const char *errstr = lua_tolstring(lstate, -1, &len);
     api_set_error(err, kErrorTypeValidation,

src/nvim/lua/executor.h

@@ -26,7 +26,7 @@ typedef struct {
 } nlua_ref_state_t;
 
 #define NLUA_EXEC_STATIC(cstr, arg, mode, arena, err) \
-  nlua_exec(STATIC_CSTR_AS_STRING(cstr), arg, mode, arena, err)
+  nlua_exec(STATIC_CSTR_AS_STRING(cstr), NULL, arg, mode, arena, err)
 
 #define NLUA_CLEAR_REF(x) \
   do { \

src/nvim/main.c

@@ -958,7 +958,7 @@ static void remote_request(mparm_T *params, int remote_args, char *server_addr,
   ADD_C(a, CSTR_AS_OBJ(connect_error));
   ADD_C(a, ARRAY_OBJ(args));
   String s = STATIC_CSTR_AS_STRING("return vim._cs_remote(...)");
-  Object o = nlua_exec(s, a, kRetObject, NULL, &err);
+  Object o = nlua_exec(s, NULL, a, kRetObject, NULL, &err);
   kv_destroy(args);
   if (ERROR_SET(&err)) {
     fprintf(stderr, "%s\n", err.msg);
@@ -2059,7 +2059,8 @@ static void do_exrc_initialization(void)
     str = nlua_read_secure(VIMRC_LUA_FILE);
     if (str != NULL) {
       Error err = ERROR_INIT;
-      nlua_exec(cstr_as_string(str), (Array)ARRAY_DICT_INIT, kRetNilBool, NULL, &err);
+      nlua_exec(cstr_as_string(str), "@"VIMRC_LUA_FILE, (Array)ARRAY_DICT_INIT, kRetNilBool, NULL,
+                &err);
       xfree(str);
       if (ERROR_SET(&err)) {
         semsg("Error detected while processing %s:", VIMRC_LUA_FILE);

src/nvim/options.lua

@@ -2668,6 +2668,8 @@ local options = {
         in the |trust| list. Use |:trust| to manage trusted files. See also
         |vim.secure.read()|.
 
+        To get its own location, Lua exrc files can use |debug.getinfo()|.
+
         Compare 'exrc' to |editorconfig|:
         - 'exrc' can execute any code; editorconfig only specifies settings.
         - 'exrc' is Nvim-specific; editorconfig works in other editors.