fix(event-loop): check if executed register has ended

src/nvim/getchar.c

@@ -2074,7 +2074,7 @@ void vungetc(int c)
 
 /// When peeking and not getting a character, reg_executing cannot be cleared
 /// yet, so set a flag to clear it later.
-static void check_end_reg_executing(bool advance)
+void check_end_reg_executing(bool advance)
 {
   if (reg_executing != 0 && (typebuf.tb_maplen == 0 || pending_end_reg_executing)) {
     if (advance) {

src/nvim/state.c

@@ -40,7 +40,7 @@ void state_enter(VimState *s)
     int key;
 
 getkey:
-    // Expand mappings first by calling vpeekc() directly.
+    // Apply mappings first by calling vpeekc() directly.
     // - If vpeekc() returns non-NUL, there is a character already available for processing, so
     //   don't block for events. vgetc() may still block, in case of an incomplete UTF-8 sequence.
     // - If vpeekc() returns NUL, vgetc() will block, and there are three cases:
@@ -76,6 +76,9 @@ getkey:
     }
 
     if (key == K_EVENT) {
+      // An event handler may use the value of reg_executing.
+      // Clear it if it should be cleared when getting the next character.
+      check_end_reg_executing(true);
       may_sync_undo();
     }
 

test/functional/editor/macro_spec.lua

@@ -6,6 +6,7 @@ local feed = helpers.feed
 local clear = helpers.clear
 local expect = helpers.expect
 local command = helpers.command
+local funcs = helpers.funcs
 local meths = helpers.meths
 local insert = helpers.insert
 local curbufmeths = helpers.curbufmeths
@@ -54,6 +55,19 @@ describe('immediately after a macro has finished executing,', function()
     command([[let @a = 'gg0']])
   end)
 
+  describe('reg_executing() from RPC returns an empty string', function()
+    it('if the macro does not end with a <Nop> mapping', function()
+      feed('@a')
+      eq('', funcs.reg_executing())
+    end)
+
+    it('if the macro ends with a <Nop> mapping', function()
+      command('nnoremap 0 <Nop>')
+      feed('@a')
+      eq('', funcs.reg_executing())
+    end)
+  end)
+
   describe('characters from a mapping are not treated as a part of the macro #18015', function()
     before_each(function()
       command('nnoremap s qa')