api helpers: Also save and restore did_emsg

src/nvim/api/private/helpers.c

@@ -46,20 +46,22 @@ typedef struct {
 void try_enter(TryState *const tstate)
 {
   *tstate = (TryState) {
+    .current_exception = current_exception,
+    .msg_list = (const struct msglist *const *)msg_list,
+    .private_msg_list = NULL,
     .trylevel = trylevel,
     .got_int = got_int,
     .did_throw = did_throw,
     .need_rethrow = need_rethrow,
-    .current_exception = current_exception,
+    .did_emsg = did_emsg,
-    .msg_list = (const struct msglist *const *)msg_list,
-    .private_msg_list = NULL,
   };
+  msg_list = &tstate->private_msg_list;
+  current_exception = NULL;
   trylevel = 1;
   got_int = false;
   did_throw = false;
   need_rethrow = false;
-  msg_list = &tstate->private_msg_list;
+  did_emsg = false;
-  current_exception = NULL;
 }
 
 /// End try block, set the error message if any and restore previous state
@@ -79,14 +81,17 @@ bool try_leave(const TryState *const tstate, Error *const err)
   assert(!need_rethrow);
   assert(!got_int);
   assert(!did_throw);
+  assert(!did_emsg);
   assert(msg_list == &tstate->private_msg_list);
   assert(*msg_list == NULL);
   assert(current_exception == NULL);
+  msg_list = (struct msglist **)tstate->msg_list;
+  current_exception = tstate->current_exception;
   trylevel = tstate->trylevel;
   got_int = tstate->got_int;
   did_throw = tstate->did_throw;
-  msg_list = (struct msglist **)tstate->msg_list;
+  need_rethrow = tstate->need_rethrow;
-  current_exception = tstate->current_exception;
+  did_emsg = tstate->did_emsg;
   return ret;
 }
 

src/nvim/api/private/helpers.h

@@ -88,13 +88,14 @@
 /// Used when caller is supposed to be operating when other VimL code is being
 /// processed and that “other VimL code” must not be affected.
 typedef struct {
+  except_T *current_exception;
+  struct msglist *private_msg_list;
+  const struct msglist *const *msg_list;
   int trylevel;
   int got_int;
   int did_throw;
   int need_rethrow;
-  except_T *current_exception;
+  int did_emsg;
-  struct msglist *private_msg_list;
-  const struct msglist *const *msg_list;
 } TryState;
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS

test/functional/ui/cmdline_highlight_spec.lua

@@ -489,6 +489,44 @@ describe('Ex commands coloring support', function()
                                               |
     ]])
   end)
+  it('does not prevent mapping error from cancelling prompt', function()
+    meths.command("cnoremap <expr> x execute('throw 42')[-1]")
+    feed(':#x')
+    screen:expect([[
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+      :#                                      |
+      {ERR:Error detected while processing :}       |
+      {ERR:E605: Exception not caught: 42}          |
+      :#^                                      |
+    ]])
+    feed('<CR>')
+    screen:expect([[
+      ^                                        |
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+                                              |
+    ]])
+    feed('<CR>')
+    screen:expect([[
+      ^                                        |
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+      {EOB:~                                       }|
+                                              |
+    ]])
+    eq('\nError detected while processing :\nE605: Exception not caught: 42',
+       meths.command_output('messages'))
+  end)
 end)
 
 -- TODO Specifically test for coloring in cmdline and expr modes