put fixup, esp. ". register close #5709 #5781

Note some bugs were judged to have too ugly a fix to solve, tests to
demonstrate these problems, and the explanation behind not fixing them
are below.

describe('register . problems', function()
  before_each(reset)

  -- The difficulty here is: The basic requirement is that the text
  -- inserted is treated as if it were typed in insert mode. This is why
  -- the paste method is to enter insert mode and enter the ". register
  -- into readbuf1.
  -- We can't add a count into the readbuf here because the insert mode
  -- count is implemented with readbuf2 which is checked for characters
  -- after readbuf1.
  -- Hence, the ".gp command (which adds extra characters into readbuf1
  -- to emulate leaving the cursor after the text by moving the cursor
  -- after inserting the text) would insert the motion characters into
  -- the buffer instead of using them to move after the insert has been
  -- done.
  -- I could probably get this working properly with a special flag put
  -- into start_redo_ins() and set in do_put(), but I think this adds
  -- much more complexity than fixing this bug justifies.
  pending('should not change the ". register with ".2p', function()
    local orig_register = funcs.getreg('.')
    feed('2".p')
    eq(orig_register, funcs.getreg('.'))
  end)

  describe("cursor positioning after undo and redo with '.'", function()
    before_each(reset)
    local function make_cursor_test(macro_string)
      return function()
        feed(macro_string)
        local afterpos = funcs.getcurpos()
        local orig_string = curbuf_contents()
        feed('u.')
        eq(afterpos, funcs.getcurpos())
        expect(orig_string)
      end
    end
    -- The difficulty here is: setting the cursor after the end of the
    -- pasted text is done by adding a motion command to the
    -- stuffbuffer after the insert.
    -- Modifying 'redobuff' is done in the code that handles inserting
    -- text and moving around.
    -- I could add a special case in ins_esc() that checks for a flag
    -- set in do_put() to add the motion character to the redo buffer,
    -- but I think that is starting to get way too convoluted for the
    -- benefit.
    pending('should be the same after ".gp and ".gpu.',
            make_cursor_test('".gp'))
    -- The difficulty here is: putting forwards is implemented by using
    -- 'a' instead of 'i' to start insert.
    -- Undoing with 'u' an insert that began with 'a' leaves the cursor
    -- where the first character was inserted, not where the cursor was
    -- when the 'a' was pressed.
    -- We account for this the first time by saving the cursor position
    -- in do_put(), but this isn't stored in redobuff for a second time
    -- around.
    -- We can't change how such a fundamental action as undo after
    -- inserting with 'a' behaves, we could add in a special case
    -- whereby we set a flag in do_put() and read it when entering
    -- insert mode but this seems like way too much to fix such a minor
    -- bug.
    pending('should be the same after ".pu. and ".pu.u.',
            make_cursor_test('".pu.'))
  end)
end)

src/nvim/normal.c

@@ -1517,10 +1517,7 @@ void do_pending_operator(cmdarg_T *cap, int old_col, bool gui_yank)
         coladvance(curwin->w_curswant);
       }
       cap->count0 = redo_VIsual_count;
-      if (redo_VIsual_count != 0)
-        cap->count1 = redo_VIsual_count;
-      else
-        cap->count1 = 1;
+      cap->count1 = (cap->count0 == 0 ? 1 : cap->count0);
     } else if (VIsual_active) {
       if (!gui_yank) {
         /* Save the current VIsual area for '< and '> marks, and "gv" */
@@ -7727,16 +7724,22 @@ static void nv_put(cmdarg_T *cap)
         savereg = copy_register(regname);
       }
 
-      /* Now delete the selected text. */
-      cap->cmdchar = 'd';
-      cap->nchar = NUL;
-      cap->oap->regname = NUL;
-      nv_operator(cap);
-      do_pending_operator(cap, 0, false);
-      empty = (curbuf->b_ml.ml_flags & ML_EMPTY);
+      // To place the cursor correctly after a blockwise put, and to leave the
+      // text in the correct position when putting over a selection with
+      // 'virtualedit' and past the end of the line, we use the 'c' operator in
+      // do_put(), which requires the visual selection to still be active.
+      if (!VIsual_active || VIsual_mode == 'V' || regname != '.') {
+        // Now delete the selected text.
+        cap->cmdchar = 'd';
+        cap->nchar = NUL;
+        cap->oap->regname = NUL;
+        nv_operator(cap);
+        do_pending_operator(cap, 0, false);
+        empty = (curbuf->b_ml.ml_flags & ML_EMPTY);
 
-      /* delete PUT_LINE_BACKWARD; */
-      cap->oap->regname = regname;
+        // delete PUT_LINE_BACKWARD;
+        cap->oap->regname = regname;
+      }
 
       /* When deleted a linewise Visual area, put the register as
        * lines to avoid it joined with the next line.  When deletion was