feat(ui): clear message history explicitly with msg_history_clear event

src/nvim/api/ui_events.in.h

@@ -174,4 +174,6 @@ void msg_ruler(Array content)
   FUNC_API_SINCE(6) FUNC_API_REMOTE_ONLY;
 void msg_history_show(Array entries)
   FUNC_API_SINCE(6) FUNC_API_REMOTE_ONLY;
+void msg_history_clear(void)
+  FUNC_API_SINCE(10) FUNC_API_REMOTE_ONLY;
 #endif  // NVIM_API_UI_EVENTS_IN_H

src/nvim/message.c

@@ -125,6 +125,8 @@ static size_t msg_ext_cur_len = 0;
 static bool msg_ext_overwrite = false;  ///< will overwrite last message
 static int msg_ext_visible = 0;  ///< number of messages currently visible
 
+static bool msg_ext_history_visible = false;
+
 /// Shouldn't clear message after leaving cmdline
 static bool msg_ext_keep_after_cmdline = false;
 
@@ -1025,6 +1027,9 @@ void ex_messages(void *const eap_p)
 
   // Display what was not skipped.
   if (ui_has(kUIMessages)) {
+    if (msg_silent) {
+      return;
+    }
     Array entries = ARRAY_DICT_INIT;
     for (; p != NULL; p = p->next) {
       if (p->msg != NULL && p->msg[0] != NUL) {
@@ -1040,6 +1045,8 @@ void ex_messages(void *const eap_p)
       }
     }
     ui_call_msg_history_show(entries);
+    msg_ext_history_visible = true;
+    wait_return(false);
   } else {
     msg_hist_off = true;
     for (; p != NULL && !got_int; p = p->next) {
@@ -3126,6 +3133,10 @@ void msg_ext_clear(bool force)
     msg_ext_visible = 0;
     msg_ext_overwrite = false;  // nothing to overwrite
   }
+  if (msg_ext_history_visible) {
+    ui_call_msg_history_clear();
+    msg_ext_history_visible = false;
+  }
 
   // Only keep once.
   msg_ext_keep_after_cmdline = false;

test/functional/ui/messages_spec.lua

@@ -304,13 +304,25 @@ describe('ui/ext_messages', function()
       {1:~                        }|
       {1:~                        }|
       {1:~                        }|
-    ]], messages={
+    ]], msg_history={
       {kind="echoerr", content={{"raa", 2}}},
       {kind="echoerr", content={{"bork", 2}}},
       {kind="echoerr", content={{"fail", 2}}},
       {kind="echoerr", content={{"extrafail", 2}}},
       {kind="echoerr", content={{"problem", 2}}}
-    }}
+    }, messages={{
+      content = {{ "Press ENTER or type command to continue", 4 }},
+      kind = "return_prompt"
+    }}}
+
+    feed '<cr>'
+    screen:expect{grid=[[
+      ^                         |
+      {1:~                        }|
+      {1:~                        }|
+      {1:~                        }|
+      {1:~                        }|
+    ]]}
   end)
 
   it('shortmess-=S', function()
@@ -455,11 +467,14 @@ describe('ui/ext_messages', function()
       alphpabe^t                |
       {1:~                        }|
       {1:~                        }|
-    ]], messages={
-      {kind="echomsg", content={{"stuff"}}},
-    }, showmode={
-      { "-- INSERT --", 3 }
-    }}
+    ]], msg_history={{
+      content = {{ "stuff" }},
+      kind = "echomsg",
+    }}, showmode={{ "-- INSERT --", 3 }},
+      messages={{
+        content = {{ "Press ENTER or type command to continue", 4}},
+        kind = "return_prompt"
+    }}}
   end)
 
   it('&showmode with macro-recording message', function()
@@ -685,12 +700,15 @@ describe('ui/ext_messages', function()
       {1:~                        }|
       {1:~                        }|
       {1:~                        }|
-    ]], messages={
+    ]], msg_history={
       {kind="echomsg", content={{"howdy"}}},
       {kind="", content={{"Type  :qa  and press <Enter> to exit Nvim"}}},
       {kind="echoerr", content={{"bork", 2}}},
       {kind="emsg", content={{"E117: Unknown function: nosuchfunction", 2}}}
-    }}
+    }, messages={{
+      content = {{ "Press ENTER or type command to continue", 4}},
+      kind = "return_prompt"
+    }}}
   end)
 
   it('implies ext_cmdline and ignores cmdheight', function()

test/functional/ui/screen.lua

@@ -242,7 +242,7 @@ end
 -- canonical order of ext keys, used  to generate asserts
 local ext_keys = {
   'popupmenu', 'cmdline', 'cmdline_block', 'wildmenu_items', 'wildmenu_pos',
-  'messages', 'showmode', 'showcmd', 'ruler', 'float_pos', 'win_viewport'
+  'messages', 'msg_history', 'showmode', 'showcmd', 'ruler', 'float_pos', 'win_viewport'
 }
 
 -- Asserts that the screen state eventually matches an expected state.
@@ -1083,6 +1083,10 @@ function Screen:_handle_msg_history_show(entries)
   self.msg_history = entries
 end
 
+function Screen:_handle_msg_history_clear()
+  self.msg_history = {}
+end
+
 function Screen:_clear_block(grid, top, bot, left, right)
   for i = top, bot do
     self:_clear_row_section(grid, i, left, right)
@@ -1171,7 +1175,7 @@ function Screen:_extstate_repr(attr_state)
 
   local msg_history = {}
   for i, entry in ipairs(self.msg_history) do
-    messages[i] = {kind=entry[1], content=self:_chunks_repr(entry[2], attr_state)}
+    msg_history[i] = {kind=entry[1], content=self:_chunks_repr(entry[2], attr_state)}
   end
 
   local win_viewport = (next(self.win_viewport) and self.win_viewport) or nil