fix(exception): remember whether message is multiline

(cherry picked from commit bfd396d986)

src/nvim/ex_docmd.c

@@ -892,7 +892,7 @@ void handle_did_throw(void)
   if (messages != NULL) {
     do {
       msglist_T *next = messages->next;
-      emsg(messages->msg);
+      emsg_multiline(messages->msg, messages->multiline);
       xfree(messages->msg);
       xfree(messages->sfile);
       xfree(messages);

src/nvim/ex_eval.c

@@ -154,7 +154,7 @@ int aborted_in_try(void)
 /// When several messages appear in the same command, the first is usually the
 /// most specific one and used as the exception value.  The "severe" flag can be
 /// set to true, if a later but severer message should be used instead.
-bool cause_errthrow(const char *mesg, bool severe, bool *ignore)
+bool cause_errthrow(const char *mesg, bool multiline, bool severe, bool *ignore)
   FUNC_ATTR_NONNULL_ALL
 {
   msglist_T *elem;
@@ -246,6 +246,7 @@ bool cause_errthrow(const char *mesg, bool severe, bool *ignore)
 
       elem = xmalloc(sizeof(msglist_T));
       elem->msg = xstrdup(mesg);
+      elem->multiline = multiline;
       elem->next = NULL;
       elem->throw_msg = NULL;
       *plist = elem;

src/nvim/ex_eval_defs.h

@@ -1,6 +1,8 @@
 #ifndef NVIM_EX_EVAL_DEFS_H
 #define NVIM_EX_EVAL_DEFS_H
 
+#include <stdbool.h>
+
 #include "nvim/pos.h"
 
 /// There is no CSF_IF, the lack of CSF_WHILE, CSF_FOR and CSF_TRY means ":if"
@@ -41,11 +43,12 @@ enum {
 /// message in the list.  See cause_errthrow().
 typedef struct msglist msglist_T;
 struct msglist {
+  msglist_T *next;  ///< next of several messages in a row
   char *msg;        ///< original message, allocated
   char *throw_msg;  ///< msg to throw: usually original one
   char *sfile;      ///< value from estack_sfile(), allocated
   linenr_T slnum;   ///< line number for "sfile"
-  msglist_T *next;  ///< next of several messages in a row
+  bool multiline;   ///< whether this is a multiline message
 };
 
 /// The exception types.

src/nvim/message.c

@@ -640,7 +640,7 @@ int emsg_not_now(void)
   return false;
 }
 
-static bool emsg_multiline(const char *s, bool multiline)
+bool emsg_multiline(const char *s, bool multiline)
 {
   int attr;
   bool ignore = false;
@@ -663,7 +663,7 @@ static bool emsg_multiline(const char *s, bool multiline)
     // be found, the message will be displayed later on.)  "ignore" is set
     // when the message should be ignored completely (used for the
     // interrupt message).
-    if (cause_errthrow(s, severe, &ignore)) {
+    if (cause_errthrow(s, multiline, severe, &ignore)) {
       if (!ignore) {
         did_emsg++;
       }

test/functional/vimscript/eval_spec.lua

@@ -153,11 +153,6 @@ end)
 
 describe("uncaught exception", function()
   before_each(clear)
-  after_each(function()
-    os.remove('throw1.vim')
-    os.remove('throw2.vim')
-    os.remove('throw3.vim')
-  end)
 
   it('is not forgotten #13490', function()
     command('autocmd BufWinEnter * throw "i am error"')
@@ -173,10 +168,45 @@ describe("uncaught exception", function()
         let result ..= 'X'
       ]]):format(i, i))
     end
+    finally(function()
+      for i = 1, 3 do
+        os.remove('throw' .. i .. '.vim')
+      end
+    end)
+
     command('set runtimepath+=. | let result = ""')
     eq('throw1', exc_exec('try | runtime! throw*.vim | endtry'))
     eq('123', eval('result'))
   end)
+
+  it('multiline exception remains multiline #25350', function()
+    local screen = Screen.new(80, 11)
+    screen:set_default_attr_ids({
+      [1] = {bold = true, reverse = true};  -- MsgSeparator
+      [2] = {foreground = Screen.colors.White, background = Screen.colors.Red};  -- ErrorMsg
+      [3] = {bold = true, foreground = Screen.colors.SeaGreen};  -- MoreMsg
+    })
+    screen:attach()
+    exec_lua([[
+      function _G.Oops()
+        error("oops")
+      end
+    ]])
+    feed(':try\rlua _G.Oops()\rendtry\r')
+    screen:expect{grid=[[
+      {1:                                                                                }|
+      :try                                                                            |
+      :  lua _G.Oops()                                                                |
+      :  endtry                                                                       |
+      {2:Error detected while processing :}                                               |
+      {2:E5108: Error executing lua [string "<nvim>"]:2: oops}                            |
+      {2:stack traceback:}                                                                |
+      {2:        [C]: in function 'error'}                                                |
+      {2:        [string "<nvim>"]:2: in function 'Oops'}                                 |
+      {2:        [string ":lua"]:1: in main chunk}                                        |
+      {3:Press ENTER or type command to continue}^                                         |
+    ]]}
+  end)
 end)
 
 describe('listing functions using :function', function()