vim-patch:9.1.0015: i_CTRL-R- no longer works in replace mode

Problem:  i_CTRL-R- no longer works in replace mode
Solution: delete characters in replace mode before putting, add a test,
          add a bit warning into the documentation, that i_CTRL-R-P/O
          is not supported in Replace mode for now

fixes: vim/vim#13792
closes: vim/vim#13816

5d5cbb2b9a

Co-authored-by: Christian Brabandt <cb@256bit.org>

runtime/doc/insert.txt

@@ -160,22 +160,22 @@ CTRL-R CTRL-O {register}			*i_CTRL-R_CTRL-O*
 		auto-indent.  Does the same as pasting with the mouse
 		|<MiddleMouse>|. When the register is linewise this will
 		insert the text above the current line, like with `P`.
-		Does not replace characters!
 		The '.' register (last inserted text) is still inserted as
 		typed.
 		After this command, the '.' register contains the command
 		typed and not the text. I.e., the literals "^R^O" and not the
 		text from the register.
+		Does not replace characters in |Replace-mode|!
 
 CTRL-R CTRL-P {register}			*i_CTRL-R_CTRL-P*
 		Insert the contents of a register literally and fix the
 		indent, like |[<MiddleMouse>|.
-		Does not replace characters!
 		The '.' register (last inserted text) is still inserted as
 		typed.
 		After this command, the '.' register contains the command
 		typed and not the text. I.e., the literals "^R^P" and not the
 		text from the register.
+		Does not replace characters in |Replace-mode|!
 
 						*i_CTRL-T*
 CTRL-T		Insert one shiftwidth of indent at the start of the current

src/nvim/ops.c

@@ -1282,9 +1282,22 @@ int insert_reg(int regname, bool literally_arg)
     } else {
       for (size_t i = 0; i < reg->y_size; i++) {
         if (regname == '-') {
+          Direction dir = BACKWARD;
+          if ((State & REPLACE_FLAG) != 0) {
+            pos_T curpos;
+            u_save_cursor();
+            del_bytes((colnr_T)strlen(reg->y_array[0]), true, false);
+            curpos = curwin->w_cursor;
+            if (oneright() == FAIL) {
+              // hit end of line, need to put forward (after the current position)
+              dir = FORWARD;
+            }
+            curwin->w_cursor = curpos;
+          }
+
           AppendCharToRedobuff(Ctrl_R);
           AppendCharToRedobuff(regname);
-          do_put(regname, NULL, BACKWARD, 1, PUT_CURSEND);
+          do_put(regname, NULL, dir, 1, PUT_CURSEND);
         } else {
           stuffescaped(reg->y_array[i], literally);
         }

test/old/testdir/test_normal.vim

@@ -4186,4 +4186,4 @@ func Test_brace_single_line()
   bw!
 endfunc
 
-" vim: shiftwidth=2 sts=2 expandtab
+" vim: shiftwidth=2 sts=2 expandtab nofoldenable

test/old/testdir/test_registers.vim

@@ -890,4 +890,24 @@ func Test_register_y_append_reset()
   bwipe!
 endfunc
 
+func Test_insert_small_delete_replace_mode()
+  new
+  call setline(1, ['foo', 'bar', 'foobar',  'bar'])
+  let @-='foo'
+  call cursor(2, 1)
+  exe ":norm! R\<C-R>-\<C-R>-"
+  call assert_equal('foofoo', getline(2))
+  call cursor(3, 1)
+  norm! D
+  call assert_equal(['foo', 'foofoo', '',  'bar'], getline(1, 4))
+  call cursor(4, 2)
+  exe ":norm! R\<C-R>-ZZZZ"
+  call assert_equal(['foo', 'foofoo', '',  'bfoobarZZZZ'], getline(1, 4))
+  call cursor(1, 1)
+  let @-=''
+  exe ":norm! R\<C-R>-ZZZ"
+  call assert_equal(['ZZZ', 'foofoo', '',  'bfoobarZZZZ'], getline(1, 4))
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab