vim-patch:8.1.2346: CTRL-R CTRL-R doesn't work with modifyOtherKeys

Problem:    CTRL-R CTRL-R doesn't work with modifyOtherKeys.
Solution:   Allow key codes when fetching argument for CTRL-R. (closes vim/vim#5266)
            Also fix CTRL-G in Insert mode.
38571a04b4

Omit test as it sends terminal codes. Use a Lua test instead.

src/nvim/edit.c

@@ -7817,11 +7817,10 @@ static void ins_reg(void)
   }
 
 
-  /*
-   * Don't map the register name. This also prevents the mode message to be
-   * deleted when ESC is hit.
-   */
-  ++no_mapping;
+  // Don't map the register name. This also prevents the mode message to be
+  // deleted when ESC is hit.
+  no_mapping++;
+  allow_keys++;
   regname = plain_vgetc();
   LANGMAP_ADJUST(regname, TRUE);
   if (regname == Ctrl_R || regname == Ctrl_O || regname == Ctrl_P) {
@@ -7831,7 +7830,8 @@ static void ins_reg(void)
     regname = plain_vgetc();
     LANGMAP_ADJUST(regname, TRUE);
   }
-  --no_mapping;
+  no_mapping--;
+  allow_keys--;
 
   // Don't call u_sync() while typing the expression or giving an error
   // message for it. Only call it explicitly.
@@ -7899,13 +7899,13 @@ static void ins_ctrl_g(void)
   // Right after CTRL-X the cursor will be after the ruler.
   setcursor();
 
-  /*
-   * Don't map the second key. This also prevents the mode message to be
-   * deleted when ESC is hit.
-   */
-  ++no_mapping;
+  // Don't map the second key. This also prevents the mode message to be
+  // deleted when ESC is hit.
+  no_mapping++;
+  allow_keys++;
   c = plain_vgetc();
-  --no_mapping;
+  no_mapping--;
+  allow_keys--;
   switch (c) {
   // CTRL-G k and CTRL-G <Up>: cursor up to Insstart.col
   case K_UP:

src/nvim/ex_getln.c

@@ -1891,6 +1891,7 @@ static int command_line_handle_key(CommandLineState *s)
   case Ctrl_R: {                      // insert register
     putcmdline('"', true);
     no_mapping++;
+    allow_keys++;
     int i = s->c = plain_vgetc();      // CTRL-R <char>
     if (i == Ctrl_O) {
       i = Ctrl_R;                      // CTRL-R CTRL-O == CTRL-R CTRL-R
@@ -1899,7 +1900,8 @@ static int command_line_handle_key(CommandLineState *s)
     if (i == Ctrl_R) {
       s->c = plain_vgetc();              // CTRL-R CTRL-R <char>
     }
-    --no_mapping;
+    no_mapping--;
+    allow_keys--;
     // Insert the result of an expression.
     // Need to save the current command line, to be able to enter
     // a new one...

test/functional/ui/input_spec.lua

@@ -8,6 +8,7 @@ local meths = helpers.meths
 local exec_lua = helpers.exec_lua
 local write_file = helpers.write_file
 local funcs = helpers.funcs
+local eval = helpers.eval
 local Screen = require('test.functional.ui.screen')
 
 before_each(clear)
@@ -216,6 +217,23 @@ it('Ctrl-6 is Ctrl-^ vim-patch:8.1.2333', function()
   eq('aaa', funcs.bufname())
 end)
 
+it('c_CTRL-R_CTRL-R, i_CTRL-R_CTRL-R, i_CTRL-G_CTRL-K work properly vim-patch:8.1.2346', function()
+  command('set timeoutlen=10')
+
+  command([[let @a = 'aaa']])
+  feed([[:let x = '<C-R><C-R>a'<CR>]])
+  eq([[let x = 'aaa']], eval('@:'))
+
+  feed('a<C-R><C-R>a<Esc>')
+  expect('aaa')
+  command('bwipe!')
+
+  feed('axx<CR>yy<C-G><C-K>a<Esc>')
+  expect([[
+  axx
+  yy]])
+end)
+
 it('typing a simplifiable key at hit-enter prompt triggers mapping vim-patch:8.2.0839', function()
   local screen = Screen.new(60,8)
   screen:set_default_attr_ids({