feat(lua): enable stack traces in error output (#16228)

13 files changed, 174 insertions, 195 deletions

diff --git a/runtime/lua/vim/shared.lua b/runtime/lua/vim/shared.lua
index b57b7ad4ad..6e40b6ca52 100644
--- a/runtime/lua/vim/shared.lua
+++ b/runtime/lua/vim/shared.lua
@@ -605,7 +605,7 @@ do
   function vim.validate(opt)
     local ok, err_msg = is_valid(opt)
     if not ok then
-      error(debug.traceback(err_msg, 2), 2)
+      error(err_msg, 2)
     end
   end
 end
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 6120deb77a..b27b1ae7a8 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -85,6 +85,27 @@ static void nlua_error(lua_State *const lstate, const char *const msg)
   lua_pop(lstate, 1);
 }
 
+/// Like lua_pcall, but use debug.traceback as errfunc.
+///
+/// @param lstate Lua interpreter state
+/// @param[in] nargs Number of arguments expected by the function being called.
+/// @param[in] nresults Number of results the function returns.
+static int nlua_pcall(lua_State *lstate, int nargs, int nresults)
+{
+  lua_getglobal(lstate, "debug");
+  lua_getfield(lstate, -1, "traceback");
+  lua_remove(lstate, -2);
+  lua_insert(lstate, -2 - nargs);
+  int status = lua_pcall(lstate, nargs, nresults, -2 - nargs);
+  if (status) {
+    lua_remove(lstate, -2);
+  } else {
+    lua_remove(lstate, -1 - nresults);
+  }
+  return status;
+}
+
+
 /// Gets the version of the current Nvim build.
 ///
 /// @param  lstate  Lua interpreter state.
@@ -115,7 +136,7 @@ static int nlua_luv_cfpcall(lua_State *lstate, int nargs, int nresult, int flags
   in_fast_callback++;
 
   int top = lua_gettop(lstate);
-  int status = lua_pcall(lstate, nargs, nresult, 0);
+  int status = nlua_pcall(lstate, nargs, nresult);
   if (status) {
     if (status == LUA_ERRMEM && !(flags & LUVF_CALLBACK_NOEXIT)) {
       // consider out of memory errors unrecoverable, just like xmalloc()
@@ -146,7 +167,7 @@ static void nlua_schedule_event(void **argv)
   lua_State *const lstate = global_lstate;
   nlua_pushref(lstate, cb);
   nlua_unref(lstate, cb);
-  if (lua_pcall(lstate, 0, 0, 0)) {
+  if (nlua_pcall(lstate, 0, 0)) {
     nlua_error(lstate, _("Error executing vim.schedule lua callback: %.*s"));
   }
 }
@@ -183,7 +204,7 @@ static void dummy_timer_close_cb(TimeWatcher *tw, void *data)
 static bool nlua_wait_condition(lua_State *lstate, int *status, bool *callback_result)
 {
   lua_pushvalue(lstate, 2);
-  *status = lua_pcall(lstate, 0, 1, 0);
+  *status = nlua_pcall(lstate, 0, 1);
   if (*status) {
     return true;  // break on error, but keep error on stack
   }
@@ -385,7 +406,7 @@ static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   {
     const char *code = (char *)&shared_module[0];
     if (luaL_loadbuffer(lstate, code, strlen(code), "@vim/shared.lua")
-        || lua_pcall(lstate, 0, 0, 0)) {
+        || nlua_pcall(lstate, 0, 0)) {
       nlua_error(lstate, _("E5106: Error while creating shared module: %.*s"));
       return 1;
     }
@@ -397,7 +418,7 @@ static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
 
     const char *code = (char *)&inspect_module[0];
     if (luaL_loadbuffer(lstate, code, strlen(code), "@vim/inspect.lua")
-        || lua_pcall(lstate, 0, 1, 0)) {
+        || nlua_pcall(lstate, 0, 1)) {
       nlua_error(lstate, _("E5106: Error while creating inspect module: %.*s"));
       return 1;
     }
@@ -406,7 +427,7 @@ static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
 
     code = (char *)&lua_F_module[0];
     if (luaL_loadbuffer(lstate, code, strlen(code), "@vim/F.lua")
-        || lua_pcall(lstate, 0, 1, 0)) {
+        || nlua_pcall(lstate, 0, 1)) {
       nlua_error(lstate, _("E5106: Error while creating vim.F module: %.*s"));
       return 1;
     }
@@ -419,7 +440,7 @@ static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   {
     const char *code = (char *)&vim_module[0];
     if (luaL_loadbuffer(lstate, code, strlen(code), "@vim.lua")
-        || lua_pcall(lstate, 0, 0, 0)) {
+        || nlua_pcall(lstate, 0, 0)) {
       nlua_error(lstate, _("E5106: Error while creating vim module: %.*s"));
       return 1;
     }
@@ -431,7 +452,7 @@ static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
 
     const char *code = (char *)&lua_meta_module[0];
     if (luaL_loadbuffer(lstate, code, strlen(code), "@vim/_meta.lua")
-        || lua_pcall(lstate, 0, 1, 0)) {
+        || nlua_pcall(lstate, 0, 1)) {
       nlua_error(lstate, _("E5106: Error while creating vim._meta module: %.*s"));
       return 1;
     }
@@ -549,6 +570,7 @@ static int nlua_print(lua_State *const lstate)
   for (; curargidx <= nargs; curargidx++) {
     lua_pushvalue(lstate, -1);  // tostring
     lua_pushvalue(lstate, curargidx);  // arg
+    // Do not use nlua_pcall here to avoid duplicate stack trace information
     if (lua_pcall(lstate, 1, 1, 0)) {
       errmsg = lua_tolstring(lstate, -1, &errmsg_len);
       goto nlua_print_error;
@@ -616,7 +638,7 @@ static int nlua_debug(lua_State *lstate)
     if (luaL_loadbuffer(lstate, (const char *)input.vval.v_string,
                         STRLEN(input.vval.v_string), "=(debug command)")) {
       nlua_error(lstate, _("E5115: Error while loading debug string: %.*s"));
-    } else if (lua_pcall(lstate, 0, 0, 0)) {
+    } else if (nlua_pcall(lstate, 0, 0)) {
       nlua_error(lstate, _("E5116: Error while calling debug string: %.*s"));
     }
     tv_clear(&input);
@@ -909,7 +931,7 @@ static void nlua_typval_exec(const char *lcmd, size_t lcmd_len, const char *name
 
   PUSH_ALL_TYPVALS(lstate, args, argcount, special);
 
-  if (lua_pcall(lstate, argcount, ret_tv ? 1 : 0, 0)) {
+  if (nlua_pcall(lstate, argcount, ret_tv ? 1 : 0)) {
     nlua_error(lstate, _("E5108: Error executing lua %.*s"));
     return;
   }
@@ -964,7 +986,7 @@ int typval_exec_lua_callable(lua_State *lstate, LuaCallable lua_cb, int argcount
 
   PUSH_ALL_TYPVALS(lstate, argvars, argcount, false);
 
-  if (lua_pcall(lstate, argcount, 1, 0)) {
+  if (nlua_pcall(lstate, argcount, 1)) {
     nlua_print(lstate);
     return ERROR_OTHER;
   }
@@ -999,7 +1021,7 @@ Object nlua_exec(const String str, const Array args, Error *err)
     nlua_push_Object(lstate, args.items[i], false);
   }
 
-  if (lua_pcall(lstate, (int)args.size, 1, 0)) {
+  if (nlua_pcall(lstate, (int)args.size, 1)) {
     size_t len;
     const char *errstr = lua_tolstring(lstate, -1, &len);
     api_set_error(err, kErrorTypeException,
@@ -1032,7 +1054,7 @@ Object nlua_call_ref(LuaRef ref, const char *name, Array args, bool retval, Erro
     nlua_push_Object(lstate, args.items[i], false);
   }
 
-  if (lua_pcall(lstate, nargs, retval ? 1 : 0, 0)) {
+  if (nlua_pcall(lstate, nargs, retval ? 1 : 0)) {
     // if err is passed, the caller will deal with the error.
     if (err) {
       size_t len;
@@ -1126,7 +1148,7 @@ void ex_luado(exarg_T *const eap)
   if (lcmd_len >= IOSIZE) {
     xfree(lcmd);
   }
-  if (lua_pcall(lstate, 0, 1, 0)) {
+  if (nlua_pcall(lstate, 0, 1)) {
     nlua_error(lstate, _("E5110: Error executing lua: %.*s"));
     return;
   }
@@ -1138,7 +1160,7 @@ void ex_luado(exarg_T *const eap)
     const char *old_line = (const char *)ml_get_buf(curbuf, l, false);
     lua_pushstring(lstate, old_line);
     lua_pushnumber(lstate, (lua_Number)l);
-    if (lua_pcall(lstate, 2, 1, 0)) {
+    if (nlua_pcall(lstate, 2, 1)) {
       nlua_error(lstate, _("E5111: Error calling lua: %.*s"));
       break;
     }
@@ -1189,7 +1211,7 @@ bool nlua_exec_file(const char *path)
     return false;
   }
 
-  if (lua_pcall(lstate, 0, 0, 0)) {
+  if (nlua_pcall(lstate, 0, 0)) {
     nlua_error(lstate, _("E5113: Error while calling lua chunk: %.*s"));
     return false;
   }
@@ -1241,7 +1263,7 @@ int nlua_expand_pat(expand_T *xp, char_u *pat, int *num_results, char_u ***resul
   // [ vim, vim._on_key, buf ]
   lua_pushlstring(lstate, (const char *)pat, STRLEN(pat));
 
-  if (lua_pcall(lstate, 1, 2, 0) != 0) {
+  if (nlua_pcall(lstate, 1, 2) != 0) {
     nlua_error(lstate,
                _("Error executing vim._expand_pat: %.*s"));
     return FAIL;
@@ -1394,7 +1416,7 @@ void nlua_execute_on_key(int c)
   // [ vim, vim._on_key, buf ]
   lua_pushlstring(lstate, (const char *)buf, buf_len);
 
-  if (lua_pcall(lstate, 1, 0, 0)) {
+  if (nlua_pcall(lstate, 1, 0)) {
     nlua_error(lstate,
                _("Error executing  vim.on_key Lua callback: %.*s"));
   }
diff --git a/test/functional/lua/api_spec.lua b/test/functional/lua/api_spec.lua
index 8551c3d2a0..81e00bba6d 100644
--- a/test/functional/lua/api_spec.lua
+++ b/test/functional/lua/api_spec.lua
@@ -2,6 +2,7 @@
 local helpers = require('test.functional.helpers')(after_each)
 
 local exc_exec = helpers.exc_exec
+local remove_trace = helpers.remove_trace
 local funcs = helpers.funcs
 local clear = helpers.clear
 local eval = helpers.eval
@@ -159,44 +160,44 @@ describe('luaeval(vim.api.…)', function()
   it('errors out correctly when working with API', function()
     -- Conversion errors
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Cannot convert given lua type',
-       exc_exec([[call luaeval("vim.api.nvim__id(vim.api.nvim__id)")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim__id(vim.api.nvim__id)")]])))
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Cannot convert given lua table',
-       exc_exec([[call luaeval("vim.api.nvim__id({1, foo=42})")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim__id({1, foo=42})")]])))
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Cannot convert given lua type',
-       exc_exec([[call luaeval("vim.api.nvim__id({42, vim.api.nvim__id})")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim__id({42, vim.api.nvim__id})")]])))
     -- Errors in number of arguments
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Expected 1 argument',
-       exc_exec([[call luaeval("vim.api.nvim__id()")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim__id()")]])))
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Expected 1 argument',
-       exc_exec([[call luaeval("vim.api.nvim__id(1, 2)")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim__id(1, 2)")]])))
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Expected 2 arguments',
-       exc_exec([[call luaeval("vim.api.nvim_set_var(1, 2, 3)")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim_set_var(1, 2, 3)")]])))
     -- Error in argument types
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Expected lua string',
-       exc_exec([[call luaeval("vim.api.nvim_set_var(1, 2)")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim_set_var(1, 2)")]])))
 
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Expected lua number',
-       exc_exec([[call luaeval("vim.api.nvim_buf_get_lines(0, 'test', 1, false)")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim_buf_get_lines(0, 'test', 1, false)")]])))
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Number is not integral',
-       exc_exec([[call luaeval("vim.api.nvim_buf_get_lines(0, 1.5, 1, false)")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim_buf_get_lines(0, 1.5, 1, false)")]])))
 
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Expected lua table',
-       exc_exec([[call luaeval("vim.api.nvim__id_float('test')")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim__id_float('test')")]])))
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Unexpected type',
-       exc_exec([[call luaeval("vim.api.nvim__id_float({[vim.type_idx]=vim.types.dictionary})")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim__id_float({[vim.type_idx]=vim.types.dictionary})")]])))
 
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Expected lua table',
-       exc_exec([[call luaeval("vim.api.nvim__id_array(1)")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim__id_array(1)")]])))
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Unexpected type',
-       exc_exec([[call luaeval("vim.api.nvim__id_array({[vim.type_idx]=vim.types.dictionary})")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim__id_array({[vim.type_idx]=vim.types.dictionary})")]])))
 
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Expected lua table',
-       exc_exec([[call luaeval("vim.api.nvim__id_dictionary(1)")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim__id_dictionary(1)")]])))
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Unexpected type',
-       exc_exec([[call luaeval("vim.api.nvim__id_dictionary({[vim.type_idx]=vim.types.array})")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim__id_dictionary({[vim.type_idx]=vim.types.array})")]])))
 
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: Expected lua table',
-       exc_exec([[call luaeval("vim.api.nvim_set_keymap('', '', '', '')")]]))
+       remove_trace(exc_exec([[call luaeval("vim.api.nvim_set_keymap('', '', '', '')")]])))
 
     -- TODO: check for errors with Tabpage argument
     -- TODO: check for errors with Window argument
diff --git a/test/functional/lua/commands_spec.lua b/test/functional/lua/commands_spec.lua
index 2e0d0ea899..9b9ba531b0 100644
--- a/test/functional/lua/commands_spec.lua
+++ b/test/functional/lua/commands_spec.lua
@@ -17,6 +17,7 @@ local pcall_err = helpers.pcall_err
 local write_file = helpers.write_file
 local exec_capture = helpers.exec_capture
 local curbufmeths = helpers.curbufmeths
+local remove_trace = helpers.remove_trace
 
 before_each(clear)
 
@@ -46,9 +47,9 @@ describe(':lua command', function()
     eq([[Vim(lua):E5107: Error loading lua [string ":lua"]:0: unexpected symbol near ')']],
        pcall_err(command, 'lua ()'))
     eq([[Vim(lua):E5108: Error executing lua [string ":lua"]:1: TEST]],
-       exc_exec('lua error("TEST")'))
+       remove_trace(exc_exec('lua error("TEST")')))
     eq([[Vim(lua):E5108: Error executing lua [string ":lua"]:1: Invalid buffer id: -10]],
-       exc_exec('lua vim.api.nvim_buf_set_lines(-10, 1, 1, false, {"TEST"})'))
+       remove_trace(exc_exec('lua vim.api.nvim_buf_set_lines(-10, 1, 1, false, {"TEST"})')))
     eq({''}, curbufmeths.get_lines(0, 100, false))
   end)
   it('works with NULL errors', function()
@@ -95,15 +96,15 @@ describe(':lua command', function()
 
     feed(':lua error("fail\\nmuch error\\nsuch details")<cr>')
     screen:expect{grid=[[
-                                              |
-      {1:~                                       }|
-      {1:~                                       }|
-      {1:~                                       }|
       {2:                                        }|
       {3:E5108: Error executing lua [string ":lua}|
       {3:"]:1: fail}                              |
       {3:much error}                              |
       {3:such details}                            |
+      {3:stack traceback:}                        |
+      {3:        [C]: in function 'error'}        |
+      {3:        [string ":lua"]:1: in main chunk}|
+                                              |
       {4:Press ENTER or type command to continue}^ |
     ]]}
     feed('<cr>')
@@ -119,24 +120,24 @@ describe(':lua command', function()
       {1:~                                       }|
                                               |
     ]]}
-    eq('E5108: Error executing lua [string ":lua"]:1: fail\nmuch error\nsuch details', eval('v:errmsg'))
+    eq('E5108: Error executing lua [string ":lua"]:1: fail\nmuch error\nsuch details', remove_trace(eval('v:errmsg')))
 
     local status, err = pcall(command,'lua error("some error\\nin a\\nAPI command")')
     local expected = 'Vim(lua):E5108: Error executing lua [string ":lua"]:1: some error\nin a\nAPI command'
     eq(false, status)
-    eq(expected, string.sub(err, -string.len(expected)))
+    eq(expected, string.sub(remove_trace(err), -string.len(expected)))
 
     feed(':messages<cr>')
     screen:expect{grid=[[
-                                              |
-      {1:~                                       }|
-      {1:~                                       }|
-      {1:~                                       }|
       {2:                                        }|
       {3:E5108: Error executing lua [string ":lua}|
       {3:"]:1: fail}                              |
       {3:much error}                              |
       {3:such details}                            |
+      {3:stack traceback:}                        |
+      {3:        [C]: in function 'error'}        |
+      {3:        [string ":lua"]:1: in main chunk}|
+                                              |
       {4:Press ENTER or type command to continue}^ |
     ]]}
   end)
@@ -219,7 +220,7 @@ describe(':luafile', function()
        exc_exec('luafile ' .. fname))
     write_file(fname, 'vimm.api.nvim_buf_set_lines(1, 1, 2, false, {"ETTS"})')
     eq(("Vim(luafile):E5113: Error while calling lua chunk: %s:1: attempt to index global 'vimm' (a nil value)"):format(fname),
-       exc_exec('luafile ' .. fname))
+        remove_trace(exc_exec('luafile ' .. fname)))
   end)
   it('works with NULL errors', function()
     write_file(fname, 'error(nil)')
diff --git a/test/functional/lua/loop_spec.lua b/test/functional/lua/loop_spec.lua
index 992d1666f6..7f3787d7bf 100644
--- a/test/functional/lua/loop_spec.lua
+++ b/test/functional/lua/loop_spec.lua
@@ -84,14 +84,14 @@ describe('vim.loop', function()
 
     screen:expect([[
                                                         |
-      {1:~                                                 }|
-      {1:~                                                 }|
-      {1:~                                                 }|
-      {1:~                                                 }|
       {2:                                                  }|
       {3:Error executing luv callback:}                     |
       {3:[string "<nvim>"]:5: E5560: nvim_set_var must not }|
       {3:be called in a lua loop callback}                  |
+      {3:stack traceback:}                                  |
+      {3:        [C]: in function 'nvim_set_var'}           |
+      {3:        [string "<nvim>"]:5: in function <[string }|
+      {3:"<nvim>"]:2>}                                      |
       {4:Press ENTER or type command to continue}^           |
     ]])
     feed('<cr>')
diff --git a/test/functional/lua/luaeval_spec.lua b/test/functional/lua/luaeval_spec.lua
index ab76e71a12..c543dd1995 100644
--- a/test/functional/lua/luaeval_spec.lua
+++ b/test/functional/lua/luaeval_spec.lua
@@ -4,6 +4,7 @@ local Screen = require('test.functional.ui.screen')
 
 local pcall_err = helpers.pcall_err
 local exc_exec = helpers.exc_exec
+local remove_trace = helpers.remove_trace
 local exec_lua = helpers.exec_lua
 local command = helpers.command
 local meths = helpers.meths
@@ -424,11 +425,11 @@ describe('luaeval()', function()
   it('errors out correctly when doing incorrect things in lua', function()
     -- Conversion errors
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: attempt to call field \'xxx_nonexistent_key_xxx\' (a nil value)',
-       exc_exec([[call luaeval("vim.xxx_nonexistent_key_xxx()")]]))
+       remove_trace(exc_exec([[call luaeval("vim.xxx_nonexistent_key_xxx()")]])))
     eq('Vim(call):E5108: Error executing lua [string "luaeval()"]:1: ERROR',
-       exc_exec([[call luaeval("error('ERROR')")]]))
+       remove_trace(exc_exec([[call luaeval("error('ERROR')")]])))
     eq('Vim(call):E5108: Error executing lua [NULL]',
-       exc_exec([[call luaeval("error(nil)")]]))
+       remove_trace(exc_exec([[call luaeval("error(nil)")]])))
   end)
 
   it('does not leak memory when called with too long line',
diff --git a/test/functional/lua/overrides_spec.lua b/test/functional/lua/overrides_spec.lua
index 636479b81f..b0712ff366 100644
--- a/test/functional/lua/overrides_spec.lua
+++ b/test/functional/lua/overrides_spec.lua
@@ -161,15 +161,15 @@ describe('debug.debug', function()
       {0:~                                                    }|
       {0:~                                                    }|
       {0:~                                                    }|
-      {0:~                                                    }|
-      {0:~                                                    }|
-      {0:~                                                    }|
       nil                                                  |
       lua_debug> print("TEST")                             |
       TEST                                                 |
                                                            |
       {E:E5108: Error executing lua [string ":lua"]:5: attempt}|
       {E: to perform arithmetic on local 'a' (a nil value)}    |
+      {E:stack traceback:}                                     |
+      {E:        [string ":lua"]:5: in function 'Test'}        |
+      {E:        [string ":lua"]:1: in main chunk}             |
       Interrupt: {cr:Press ENTER or type command to continue}^   |
     ]]}
     feed('<C-l>:lua Test()\n')
@@ -197,13 +197,13 @@ describe('debug.debug', function()
       {0:~                                                    }|
       {0:~                                                    }|
       {0:~                                                    }|
-      {0:~                                                    }|
-      {0:~                                                    }|
-      {0:~                                                    }|
       nil                                                  |
       lua_debug>                                           |
       {E:E5108: Error executing lua [string ":lua"]:5: attempt}|
       {E: to perform arithmetic on local 'a' (a nil value)}    |
+      {E:stack traceback:}                                     |
+      {E:        [string ":lua"]:5: in function 'Test'}        |
+      {E:        [string ":lua"]:1: in main chunk}             |
       {cr:Press ENTER or type command to continue}^              |
     ]]}
   end)
diff --git a/test/functional/lua/vim_spec.lua b/test/functional/lua/vim_spec.lua
index 5f903e7d5f..3832d27a22 100644
--- a/test/functional/lua/vim_spec.lua
+++ b/test/functional/lua/vim_spec.lua
@@ -4,7 +4,6 @@ local Screen = require('test.functional.ui.screen')
 
 local funcs = helpers.funcs
 local meths = helpers.meths
-local dedent = helpers.dedent
 local command = helpers.command
 local insert = helpers.insert
 local clear = helpers.clear
@@ -19,6 +18,7 @@ local source = helpers.source
 local NIL = helpers.NIL
 local retry = helpers.retry
 local next_msg = helpers.next_msg
+local remove_trace = helpers.remove_trace
 
 before_each(clear)
 
@@ -121,11 +121,6 @@ describe('lua stdlib', function()
     eq(1, funcs.luaeval('vim.stricmp("\\0C\\0", "\\0B\\0")'))
   end)
 
-  -- for brevity, match only the error header (not the traceback)
-  local function pcall_header(...)
-    return string.gsub(string.gsub(pcall_err(exec_lua, ...), '[\r\n].*', ''), '^Error executing lua: ', '')
-  end
-
   it('vim.startswith', function()
     eq(true, funcs.luaeval('vim.startswith("123", "1")'))
     eq(true, funcs.luaeval('vim.startswith("123", "")'))
@@ -136,8 +131,10 @@ describe('lua stdlib', function()
     eq(false, funcs.luaeval('vim.startswith("123", "2")'))
     eq(false, funcs.luaeval('vim.startswith("123", "1234")'))
 
-    eq("vim/shared.lua:0: prefix: expected string, got nil", pcall_header 'return vim.startswith("123", nil)')
-    eq("vim/shared.lua:0: s: expected string, got nil", pcall_header 'return vim.startswith(nil, "123")')
+    eq("Error executing lua: vim/shared.lua:0: prefix: expected string, got nil",
+      pcall_err(exec_lua, 'return vim.startswith("123", nil)'))
+    eq("Error executing lua: vim/shared.lua:0: s: expected string, got nil",
+      pcall_err(exec_lua, 'return vim.startswith(nil, "123")'))
   end)
 
   it('vim.endswith', function()
@@ -150,8 +147,10 @@ describe('lua stdlib', function()
     eq(false, funcs.luaeval('vim.endswith("123", "2")'))
     eq(false, funcs.luaeval('vim.endswith("123", "1234")'))
 
-    eq("vim/shared.lua:0: suffix: expected string, got nil", pcall_header 'return vim.endswith("123", nil)')
-    eq("vim/shared.lua:0: s: expected string, got nil", pcall_header 'return vim.endswith(nil, "123")')
+    eq("Error executing lua: vim/shared.lua:0: suffix: expected string, got nil",
+      pcall_err(exec_lua, 'return vim.endswith("123", nil)'))
+    eq("Error executing lua: vim/shared.lua:0: s: expected string, got nil",
+      pcall_err(exec_lua, 'return vim.endswith(nil, "123")'))
   end)
 
   it("vim.str_utfindex/str_byteindex", function()
@@ -233,7 +232,7 @@ describe('lua stdlib', function()
     ]])
 
     feed("<cr>")
-    eq('Error executing vim.schedule lua callback: [string "<nvim>"]:2: big failure\nvery async', eval("v:errmsg"))
+    eq('Error executing vim.schedule lua callback: [string "<nvim>"]:2: big failure\nvery async', remove_trace(eval("v:errmsg")))
 
     local screen = Screen.new(60,5)
     screen:set_default_attr_ids({
@@ -259,10 +258,10 @@ describe('lua stdlib', function()
       end)
     ]])
     screen:expect{grid=[[
-                                                                  |
-      {2:                                                            }|
-      {3:Error executing vim.schedule lua callback: [string "<nvim>"]}|
-      {3::2: Vim(echo):E115: Missing quote: 'err}                     |
+      {3:stack traceback:}                                            |
+      {3:        [C]: in function 'nvim_command'}                     |
+      {3:        [string "<nvim>"]:2: in function <[string "<nvim>"]:}|
+      {3:1>}                                                          |
       {4:Press ENTER or type command to continue}^                     |
     ]]}
   end)
@@ -306,22 +305,11 @@ describe('lua stdlib', function()
 
     -- Validates args.
     eq(true, pcall(split, 'string', 'string'))
-    eq(dedent([[
-        Error executing lua: vim/shared.lua:0: s: expected string, got number
-        stack traceback:
-            vim/shared.lua:0: in function 'gsplit'
-            vim/shared.lua:0: in function <vim/shared.lua:0>]]),
+    eq('Error executing lua: vim/shared.lua:0: s: expected string, got number',
       pcall_err(split, 1, 'string'))
-    eq(dedent([[
-        Error executing lua: vim/shared.lua:0: sep: expected string, got number
-        stack traceback:
-            vim/shared.lua:0: in function 'gsplit'
-            vim/shared.lua:0: in function <vim/shared.lua:0>]]),
+    eq('Error executing lua: vim/shared.lua:0: sep: expected string, got number',
       pcall_err(split, 'string', 1))
-    eq(dedent([[
-        Error executing lua: vim/shared.lua:0: kwargs: expected table, got number
-        stack traceback:
-            vim/shared.lua:0: in function <vim/shared.lua:0>]]),
+    eq('Error executing lua: vim/shared.lua:0: kwargs: expected table, got number',
       pcall_err(split, 'string', 'string', 1))
   end)
 
@@ -342,10 +330,7 @@ describe('lua stdlib', function()
     end
 
     -- Validates args.
-    eq(dedent([[
-        Error executing lua: vim/shared.lua:0: s: expected string, got number
-        stack traceback:
-            vim/shared.lua:0: in function <vim/shared.lua:0>]]),
+    eq('Error executing lua: vim/shared.lua:0: s: expected string, got number',
       pcall_err(trim, 2))
   end)
 
@@ -424,10 +409,7 @@ describe('lua stdlib', function()
     eq('foo%%%-bar', exec_lua([[return vim.pesc(vim.pesc('foo-bar'))]]))
 
     -- Validates args.
-    eq(dedent([[
-        Error executing lua: vim/shared.lua:0: s: expected string, got number
-        stack traceback:
-            vim/shared.lua:0: in function <vim/shared.lua:0>]]),
+    eq('Error executing lua: vim/shared.lua:0: s: expected string, got number',
       pcall_err(exec_lua, [[return vim.pesc(2)]]))
   end)
 
@@ -710,10 +692,7 @@ describe('lua stdlib', function()
 
   it('vim.list_extend', function()
     eq({1,2,3}, exec_lua [[ return vim.list_extend({1}, {2,3}) ]])
-    eq(dedent([[
-        Error executing lua: vim/shared.lua:0: src: expected table, got nil
-        stack traceback:
-            vim/shared.lua:0: in function <vim/shared.lua:0>]]),
+    eq('Error executing lua: vim/shared.lua:0: src: expected table, got nil',
       pcall_err(exec_lua, [[ return vim.list_extend({1}, nil) ]]))
     eq({1,2}, exec_lua [[ return vim.list_extend({1}, {2;a=1}) ]])
     eq(true, exec_lua [[ local a = {1} return vim.list_extend(a, {2;a=1}) == a ]])
@@ -845,12 +824,12 @@ describe('lua stdlib', function()
       end)
     ]])
     screen:expect{grid=[[
-      foo                                               |
-      {1:~                                                 }|
-      {2:                                                  }|
-      {3:Error executing luv callback:}                     |
       {3:[string "<nvim>"]:6: E5560: rpcrequest must not be}|
       {3: called in a lua loop callback}                    |
+      {3:stack traceback:}                                  |
+      {3:        [C]: in function 'rpcrequest'}             |
+      {3:        [string "<nvim>"]:6: in function <[string }|
+      {3:"<nvim>"]:2>}                                      |
       {4:Press ENTER or type command to continue}^           |
     ]]}
     feed('<cr>')
@@ -914,76 +893,37 @@ describe('lua stdlib', function()
     exec_lua("vim.validate{arg1={{}, 't' }, arg2={ 'foo', 's' }}")
     exec_lua("vim.validate{arg1={2, function(a) return (a % 2) == 0  end, 'even number' }}")
 
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: opt[1]: expected table, got number
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: opt[1]: expected table, got number',
       pcall_err(exec_lua, "vim.validate{ 1, 'x' }"))
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: invalid type name: x
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: invalid type name: x',
       pcall_err(exec_lua, "vim.validate{ arg1={ 1, 'x' }}"))
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: invalid type name: 1
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: invalid type name: 1',
       pcall_err(exec_lua, "vim.validate{ arg1={ 1, 1 }}"))
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: invalid type name: nil
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: invalid type name: nil',
       pcall_err(exec_lua, "vim.validate{ arg1={ 1 }}"))
 
     -- Validated parameters are required by default.
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: arg1: expected string, got nil
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: arg1: expected string, got nil',
       pcall_err(exec_lua, "vim.validate{ arg1={ nil, 's' }}"))
     -- Explicitly required.
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: arg1: expected string, got nil
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: arg1: expected string, got nil',
       pcall_err(exec_lua, "vim.validate{ arg1={ nil, 's', false }}"))
 
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: arg1: expected table, got number
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: arg1: expected table, got number',
       pcall_err(exec_lua, "vim.validate{arg1={1, 't'}}"))
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: arg2: expected string, got number
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: arg2: expected string, got number',
       pcall_err(exec_lua, "vim.validate{arg1={{}, 't'}, arg2={1, 's'}}"))
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: arg2: expected string, got nil
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: arg2: expected string, got nil',
       pcall_err(exec_lua, "vim.validate{arg1={{}, 't'}, arg2={nil, 's'}}"))
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: arg2: expected string, got nil
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: arg2: expected string, got nil',
       pcall_err(exec_lua, "vim.validate{arg1={{}, 't'}, arg2={nil, 's'}}"))
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: arg1: expected even number, got 3
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: arg1: expected even number, got 3',
       pcall_err(exec_lua, "vim.validate{arg1={3, function(a) return a == 1 end, 'even number'}}"))
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: arg1: expected ?, got 3
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: arg1: expected ?, got 3',
       pcall_err(exec_lua, "vim.validate{arg1={3, function(a) return a == 1 end}}"))
 
     -- Pass an additional message back.
-    eq(dedent([[
-        Error executing lua: [string "<nvim>"]:0: arg1: expected ?, got 3. Info: TEST_MSG
-        stack traceback:
-            [string "<nvim>"]:0: in main chunk]]),
+    eq('Error executing lua: [string "<nvim>"]:0: arg1: expected ?, got 3. Info: TEST_MSG',
       pcall_err(exec_lua, "vim.validate{arg1={3, function(a) return a == 1, 'TEST_MSG' end}}"))
   end)
 
@@ -2133,9 +2073,10 @@ describe('lua stdlib', function()
     end)
 
     it('should not crash when callback errors', function()
-      eq({false, '[string "<nvim>"]:1: As Expected'}, exec_lua [[
+      local result = exec_lua [[
         return {pcall(function() vim.wait(1000, function() error("As Expected") end) end)}
-      ]])
+      ]]
+      eq({false, '[string "<nvim>"]:1: As Expected'}, {result[1], remove_trace(result[2])})
     end)
 
     it('if callback is passed, it must be a function', function()
diff --git a/test/functional/plugin/health_spec.lua b/test/functional/plugin/health_spec.lua
index b84e9d1533..b567b3e20c 100644
--- a/test/functional/plugin/health_spec.lua
+++ b/test/functional/plugin/health_spec.lua
@@ -134,7 +134,7 @@ describe('health.vim', function()
       command("checkhealth test_plug*")
       local buf_lines = helpers.curbuf('get_lines', 0, -1, true)
       -- avoid dealing with path separators
-      local received = table.concat(buf_lines, '\n', 1, #buf_lines - 2)
+      local received = table.concat(buf_lines, '\n', 1, #buf_lines - 5)
       local expected = helpers.dedent([[
 
         test_plug: require("test_plug.health").check()
@@ -175,10 +175,10 @@ describe('health.vim', function()
     it("gracefully handles broken lua healthcheck", function()
       command("checkhealth test_plug.submodule_failed")
       local buf_lines = helpers.curbuf('get_lines', 0, -1, true)
-      local received = table.concat(buf_lines, '\n', 1, #buf_lines - 2)
+      local received = table.concat(buf_lines, '\n', 1, #buf_lines - 5)
       -- avoid dealing with path separators
       local lua_err = "attempt to perform arithmetic on a nil value"
-      local last_line = buf_lines[#buf_lines - 1]
+      local last_line = buf_lines[#buf_lines - 4]
       assert(string.find(last_line, lua_err) ~= nil, "Lua error not present")
 
       local expected = global_helpers.dedent([[
diff --git a/test/functional/plugin/lsp_spec.lua b/test/functional/plugin/lsp_spec.lua
index 37fba02e0e..c025e9f4ab 100644
--- a/test/functional/plugin/lsp_spec.lua
+++ b/test/functional/plugin/lsp_spec.lua
@@ -1153,15 +1153,9 @@ describe('LSP', function()
     end)
 
     it('should invalid cmd argument', function()
-      eq(dedent([[
-          Error executing lua: .../lsp.lua:0: cmd: expected list, got nvim
-          stack traceback:
-              .../lsp.lua:0: in function <.../lsp.lua:0>]]),
+      eq('Error executing lua: .../lsp.lua:0: cmd: expected list, got nvim',
         pcall_err(_cmd_parts, 'nvim'))
-      eq(dedent([[
-          Error executing lua: .../lsp.lua:0: cmd argument: expected string, got number
-          stack traceback:
-              .../lsp.lua:0: in function <.../lsp.lua:0>]]),
+      eq('Error executing lua: .../lsp.lua:0: cmd argument: expected string, got number',
         pcall_err(_cmd_parts, {'nvim', 1}))
     end)
   end)
diff --git a/test/functional/terminal/tui_spec.lua b/test/functional/terminal/tui_spec.lua
index f7520b14d4..6b9586b4de 100644
--- a/test/functional/terminal/tui_spec.lua
+++ b/test/functional/terminal/tui_spec.lua
@@ -494,6 +494,8 @@ describe('TUI', function()
   it('paste: recovers from vim.paste() failure', function()
     child_session:request('nvim_exec_lua', [[
       _G.save_paste_fn = vim.paste
+      -- Stack traces for this test are non-deterministic, so disable them
+      _G.debug.traceback = function(msg) return msg end
       vim.paste = function(lines, phase) error("fake fail") end
     ]], {})
     -- Prepare something for dot-repeat/redo.
@@ -514,7 +516,7 @@ describe('TUI', function()
       foo                                               |
                                                         |
       {5:                                                  }|
-      {8:paste: Error executing lua: [string "<nvim>"]:2: f}|
+      {8:paste: Error executing lua: [string "<nvim>"]:4: f}|
       {8:ake fail}                                          |
       {10:Press ENTER or type command to continue}{1: }          |
       {3:-- TERMINAL --}                                    |
@@ -579,12 +581,16 @@ describe('TUI', function()
 
   it("paste: 'nomodifiable' buffer", function()
     child_session:request('nvim_command', 'set nomodifiable')
+    child_session:request('nvim_exec_lua', [[
+      -- Stack traces for this test are non-deterministic, so disable them
+      _G.debug.traceback = function(msg) return msg end
+    ]], {})
     feed_data('\027[200~fail 1\nfail 2\n\027[201~')
     screen:expect{grid=[[
                                                         |
       {4:~                                                 }|
       {5:                                                  }|
-      {MATCH:paste: Error executing lua: vim.lua:%d+: Vim:E21: }|
+      {8:paste: Error executing lua: vim.lua:243: Vim:E21: }|
       {8:Cannot make changes, 'modifiable' is off}          |
       {10:Press ENTER or type command to continue}{1: }          |
       {3:-- TERMINAL --}                                    |
@@ -671,8 +677,8 @@ describe('TUI', function()
       item 2997                                         |
       item 2998                                         |
       item 2999                                         |
-      item 3000 en{1:d}d                                    |
-      {5:[No Name] [+]                   5999,13        Bot}|
+      item 3000 en{1:d}                                     |
+      {5:[No Name] [+]                   3000,13        Bot}|
                                                         |
       {3:-- TERMINAL --}                                    |
     ]])
diff --git a/test/functional/ui/messages_spec.lua b/test/functional/ui/messages_spec.lua
index c238898244..f038348253 100644
--- a/test/functional/ui/messages_spec.lua
+++ b/test/functional/ui/messages_spec.lua
@@ -750,8 +750,13 @@ describe('ui/ext_messages', function()
       {1:~                        }|
       {1:~                        }|
     ]], messages={{
-        content = {{'E5108: Error executing lua [string ":lua"]:1: such\nmultiline\nerror', 2}},
-        kind = "lua_error"
+        content = {{[[E5108: Error executing lua [string ":lua"]:1: such
+multiline
+error
+stack traceback:
+	[C]: in function 'error'
+	[string ":lua"]:1: in main chunk]], 2}},
+        kind = "lua_error",
      }}}
   end)
 
@@ -1048,12 +1053,12 @@ vimComment     xxx match /\s"[^\-:.%#=*].*$/ms=s+1,lc=1  excludenl contains=@vim
     -- edge case: just covers statusline
     feed(':set colorcolumn=5 | lua error("x\\n\\nx")<cr>')
     screen:expect{grid=[[
-                                                                  |
-      {1:~                                                           }|
-      {3:                                                            }|
       {2:E5108: Error executing lua [string ":lua"]:1: x}             |
                                                                   |
       {2:x}                                                           |
+      {2:stack traceback:}                                            |
+      {2:        [C]: in function 'error'}                            |
+      {2:        [string ":lua"]:1: in main chunk}                    |
       {4:Press ENTER or type command to continue}^                     |
     ]]}
 
@@ -1071,24 +1076,24 @@ vimComment     xxx match /\s"[^\-:.%#=*].*$/ms=s+1,lc=1  excludenl contains=@vim
     -- edge case: just covers lowest window line
     feed(':set colorcolumn=5 | lua error("x\\n\\n\\nx")<cr>')
     screen:expect{grid=[[
-                                                                  |
-      {3:                                                            }|
       {2:E5108: Error executing lua [string ":lua"]:1: x}             |
                                                                   |
                                                                   |
       {2:x}                                                           |
-      {4:Press ENTER or type command to continue}^                     |
+      {2:stack traceback:}                                            |
+      {2:        [C]: in function 'error'}                            |
+      {4:-- More --}^                                                  |
     ]]}
 
     feed('<cr>')
     screen:expect{grid=[[
                                                                   |
-      {1:~                                                           }|
-      {8:[No Name]                                                   }|
-      ^    {9: }                                                       |
-      {1:~                                                           }|
-      {3:[No Name]                                                   }|
                                                                   |
+      {2:x}                                                           |
+      {2:stack traceback:}                                            |
+      {2:        [C]: in function 'error'}                            |
+      {2:        [string ":lua"]:1: in main chunk}                    |
+      {4:Press ENTER or type command to continue}^                     |
     ]]}
   end)
 end)
@@ -1360,14 +1365,14 @@ aliquip ex ea commodo consequat.]])
     ]]}
     feed('d')
     screen:expect{grid=[[
+      {2:mpor}                               |
       {2:incididunt ut labore et dolore magn}|
       {2:a aliqua.}                          |
       {2:Ut enim ad minim veniam, quis nostr}|
       {2:ud xercitation}                     |
       {2:ullamco laboris nisi ut}            |
       {2:aliquip ex ea commodo consequat.}   |
-      {4:Press ENTER or type command to cont}|
-      {4:inue}^                               |
+      {4:-- More --}^                         |
     ]]}
     feed('u')
     screen:expect{grid=[[
@@ -1460,14 +1465,14 @@ aliquip ex ea commodo consequat.]])
     ]]}
     feed('d')
     screen:expect{grid=[[
+      {3:mpor}{5:                               }|
       {3:incididunt ut labore et dolore magn}|
       {3:a aliqua.}{5:                          }|
       {3:Ut enim ad minim veniam, quis nostr}|
       {3:ud xercitation}{5:                     }|
       {3:ullamco laboris nisi ut}{5:            }|
       {3:aliquip ex ea commodo consequat.}{5:   }|
-      {6:Press ENTER or type command to cont}|
-      {6:inue}{5:^                               }|
+      {6:-- More --}{5:^                         }|
     ]]}
     feed('u')
     screen:expect{grid=[[
@@ -1667,6 +1672,7 @@ aliquip ex ea commodo consequat.]])
     -- wrapped at the new screen size.
     feed('<cr>')
     screen:expect{grid=[[
+      {2:":lua"]:1: Lorem ipsum dolor s}|
       {2:et, consectetur}               |
       {2:adipisicing elit, sed do eiusm}|
       {2:mpore}                         |
@@ -1677,8 +1683,7 @@ aliquip ex ea commodo consequat.]])
       {2:ullamco laboris nisi ut}       |
       {2:aliquip ex ea commodo consequa}|
       {2:t.}                            |
-      {4:Press ENTER or type command to}|
-      {4: continue}^                     |
+      {4:-- More --}^                    |
     ]]}
 
     feed('q')
diff --git a/test/helpers.lua b/test/helpers.lua
index 9ac3904776..09b113c01d 100644
--- a/test/helpers.lua
+++ b/test/helpers.lua
@@ -155,12 +155,20 @@ function module.pcall_err_withfile(fn, ...)
   return errmsg
 end
 
-function module.pcall_err(fn, ...)
+function module.pcall_err_withtrace(fn, ...)
   local errmsg = module.pcall_err_withfile(fn, ...)
 
   return errmsg:gsub('.../helpers.lua:0: ', '')
 end
 
+function module.pcall_err(...)
+  return module.remove_trace(module.pcall_err_withtrace(...))
+end
+
+function module.remove_trace(s)
+  return (s:gsub("\n%s*stack traceback:.*", ""))
+end
+
 -- initial_path:  directory to recurse into
 -- re:            include pattern (string)
 -- exc_re:        exclude pattern(s) (string or table)