fix(marks): wrong line('w$', win) with conceal_lines (#37047)

Background:
Suppose a window has concealed lines, and sets conceallevel>2,
concealcursor="". The concealed lines are displayed if the window is
curwin and the cursor is on the those lines.

Problem:
line('w$', win) switches curwin to win, and then does validate_botline
for curwin. It computes botline assuming the concealed lines displayed,
resulting in a smaller value than the actual botline that the user sees.

Solution:
Evaluate line('w$', win) without switching curwin.
Apply similar changes to other functions that switches curwin.

Co-authored-by: zeertzjq <zeertzjq@outlook.com>

src/nvim/eval.c

@@ -5260,14 +5260,17 @@ int buf_charidx_to_byteidx(buf_T *buf, linenr_T lnum, int charidx)
 /// @param[in]  dollar_lnum  True when "$" is last line.
 /// @param[out]  ret_fnum  Set to fnum for marks.
 /// @param[in]  charcol  True to return character column.
+/// @param[in]  wp  Window for which to get the position.
 ///
 /// @return Pointer to position or NULL in case of error (e.g. invalid type).
 pos_T *var2fpos(const typval_T *const tv, const bool dollar_lnum, int *const ret_fnum,
-                const bool charcol)
+                const bool charcol, win_T *wp)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
 {
   static pos_T pos;
 
+  buf_T *bp = wp->w_buffer;
+
   // Argument can be [lnum, col, coladd].
   if (tv->v_type == VAR_LIST) {
     bool error = false;
@@ -5279,7 +5282,7 @@ pos_T *var2fpos(const typval_T *const tv, const bool dollar_lnum, int *const ret
 
     // Get the line number.
     pos.lnum = (linenr_T)tv_list_find_nr(l, 0, &error);
-    if (error || pos.lnum <= 0 || pos.lnum > curbuf->b_ml.ml_line_count) {
+    if (error || pos.lnum <= 0 || pos.lnum > bp->b_ml.ml_line_count) {
       // Invalid line number.
       return NULL;
     }
@@ -5291,9 +5294,9 @@ pos_T *var2fpos(const typval_T *const tv, const bool dollar_lnum, int *const ret
     }
     int len;
     if (charcol) {
-      len = mb_charlen(ml_get(pos.lnum));
+      len = mb_charlen(ml_get_buf(bp, pos.lnum));
     } else {
-      len = ml_get_len(pos.lnum);
+      len = ml_get_buf_len(bp, pos.lnum);
     }
 
     // We accept "$" for the column number: last column.
@@ -5328,18 +5331,18 @@ pos_T *var2fpos(const typval_T *const tv, const bool dollar_lnum, int *const ret
   pos.lnum = 0;
   if (name[0] == '.') {
     // cursor
-    pos = curwin->w_cursor;
+    pos = wp->w_cursor;
   } else if (name[0] == 'v' && name[1] == NUL) {
     // Visual start
-    if (VIsual_active) {
+    if (VIsual_active && wp == curwin) {
       pos = VIsual;
     } else {
-      pos = curwin->w_cursor;
+      pos = wp->w_cursor;
     }
   } else if (name[0] == '\'') {
     // mark
     int mname = (uint8_t)name[1];
-    const fmark_T *const fm = mark_get(curbuf, curwin, NULL, kMarkAll, mname);
+    const fmark_T *const fm = mark_get(bp, wp, NULL, kMarkAll, mname);
     if (fm == NULL || fm->mark.lnum <= 0) {
       return NULL;
     }
@@ -5349,7 +5352,7 @@ pos_T *var2fpos(const typval_T *const tv, const bool dollar_lnum, int *const ret
   }
   if (pos.lnum != 0) {
     if (charcol) {
-      pos.col = buf_byteidx_to_charidx(curbuf, pos.lnum, pos.col);
+      pos.col = buf_byteidx_to_charidx(bp, pos.lnum, pos.col);
     }
     return &pos;
   }
@@ -5359,31 +5362,31 @@ pos_T *var2fpos(const typval_T *const tv, const bool dollar_lnum, int *const ret
   if (name[0] == 'w' && dollar_lnum) {
     // the "w_valid" flags are not reset when moving the cursor, but they
     // do matter for update_topline() and validate_botline().
-    check_cursor_moved(curwin);
+    check_cursor_moved(wp);
 
     pos.col = 0;
     if (name[1] == '0') {               // "w0": first visible line
-      update_topline(curwin);
+      update_topline(wp);
       // In silent Ex mode topline is zero, but that's not a valid line
       // number; use one instead.
-      pos.lnum = curwin->w_topline > 0 ? curwin->w_topline : 1;
+      pos.lnum = wp->w_topline > 0 ? wp->w_topline : 1;
       return &pos;
     } else if (name[1] == '$') {      // "w$": last visible line
-      validate_botline(curwin);
+      validate_botline(wp);
       // In silent Ex mode botline is zero, return zero then.
-      pos.lnum = curwin->w_botline > 0 ? curwin->w_botline - 1 : 0;
+      pos.lnum = wp->w_botline > 0 ? wp->w_botline - 1 : 0;
       return &pos;
     }
   } else if (name[0] == '$') {        // last column or line
     if (dollar_lnum) {
-      pos.lnum = curbuf->b_ml.ml_line_count;
+      pos.lnum = bp->b_ml.ml_line_count;
       pos.col = 0;
     } else {
-      pos.lnum = curwin->w_cursor.lnum;
+      pos.lnum = wp->w_cursor.lnum;
       if (charcol) {
-        pos.col = (colnr_T)mb_charlen(get_cursor_line_ptr());
+        pos.col = (colnr_T)mb_charlen(ml_get_buf(bp, wp->w_cursor.lnum));
       } else {
-        pos.col = get_cursor_line_len();
+        pos.col = ml_get_buf_len(bp, wp->w_cursor.lnum);
       }
     }
     return &pos;

src/nvim/eval/funcs.c

@@ -670,33 +670,27 @@ static void get_col(typval_T *argvars, typval_T *rettv, bool charcol)
     return;
   }
 
-  switchwin_T switchwin;
+  win_T *wp = curwin;
-  bool winchanged = false;
 
   if (argvars[1].v_type != VAR_UNKNOWN) {
     // use the window specified in the second argument
     tabpage_T *tp;
-    win_T *wp = win_id2wp_tp((int)tv_get_number(&argvars[1]), &tp);
+    wp = win_id2wp_tp((int)tv_get_number(&argvars[1]), &tp);
     if (wp == NULL || tp == NULL) {
       return;
     }
-
+    check_cursor(wp);
-    if (switch_win_noblock(&switchwin, wp, tp, true) != OK) {
-      return;
-    }
-
-    check_cursor(curwin);
-    winchanged = true;
   }
 
+  buf_T *bp = wp->w_buffer;
   colnr_T col = 0;
-  int fnum = curbuf->b_fnum;
+  int fnum = bp->b_fnum;
-  pos_T *fp = var2fpos(&argvars[0], false, &fnum, charcol);
+  pos_T *fp = var2fpos(&argvars[0], false, &fnum, charcol, wp);
-  if (fp != NULL && fnum == curbuf->b_fnum) {
+  if (fp != NULL && fnum == bp->b_fnum) {
     if (fp->col == MAXCOL) {
       // '> can be MAXCOL, get the length of the line then
-      if (fp->lnum <= curbuf->b_ml.ml_line_count) {
+      if (fp->lnum <= bp->b_ml.ml_line_count) {
-        col = ml_get_len(fp->lnum) + 1;
+        col = ml_get_buf_len(bp, fp->lnum) + 1;
       } else {
         col = MAXCOL;
       }
@@ -704,11 +698,11 @@ static void get_col(typval_T *argvars, typval_T *rettv, bool charcol)
       col = fp->col + 1;
       // col(".") when the cursor is on the NUL at the end of the line
       // because of "coladd" can be seen as an extra column.
-      if (virtual_active(curwin) && fp == &curwin->w_cursor) {
+      if (virtual_active(wp) && fp == &wp->w_cursor) {
-        char *p = get_cursor_pos_ptr();
+        char *p = ml_get_buf(bp, wp->w_cursor.lnum) + wp->w_cursor.col;
-        if (curwin->w_cursor.coladd >=
+        if (wp->w_cursor.coladd >=
-            (colnr_T)win_chartabsize(curwin, p,
+            (colnr_T)win_chartabsize(wp, p,
-                                     curwin->w_virtcol - curwin->w_cursor.coladd)) {
+                                     wp->w_virtcol - wp->w_cursor.coladd)) {
           int l;
           if (*p != NUL && p[(l = utfc_ptr2len(p))] == NUL) {
             col += l;
@@ -718,10 +712,6 @@ static void get_col(typval_T *argvars, typval_T *rettv, bool charcol)
     }
   }
   rettv->vval.v_number = col;
-
-  if (winchanged) {
-    restore_win_noblock(&switchwin, true);
-  }
 }
 
 /// "charcol()" function
@@ -2039,7 +2029,7 @@ static void getpos_both(typval_T *argvars, typval_T *rettv, bool getcurpos, bool
       fp = &pos;
     }
   } else {
-    fp = var2fpos(&argvars[0], true, &fnum, charcol);
+    fp = var2fpos(&argvars[0], true, &fnum, charcol, curwin);
   }
 
   list_T *const l = tv_list_alloc_ret(rettv, 4 + getcurpos);
@@ -3935,22 +3925,18 @@ static void f_line(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     tabpage_T *tp;
     win_T *wp = win_id2wp_tp(id, &tp);
     if (wp != NULL && tp != NULL) {
-      switchwin_T switchwin;
+      // With 'splitkeep' != cursor and in diff mode, prevent that the
-      if (switch_win_noblock(&switchwin, wp, tp, true) == OK) {
+      // window scrolls and keep the topline.
-        // With 'splitkeep' != cursor and in diff mode, prevent that the
+      if (*p_spk != 'c' || (wp->w_p_diff && curwin->w_p_diff)) {
-        // window scrolls and keep the topline.
+        skip_update_topline = true;
-        if (*p_spk != 'c' || (curwin->w_p_diff && switchwin.sw_curwin->w_p_diff)) {
-          skip_update_topline = true;
-        }
-        check_cursor(curwin);
-        fp = var2fpos(&argvars[0], true, &fnum, false);
       }
+      check_cursor(wp);
+      fp = var2fpos(&argvars[0], true, &fnum, false, wp);
       skip_update_topline = false;
-      restore_win_noblock(&switchwin, true);
     }
   } else {
     // use current window
-    fp = var2fpos(&argvars[0], true, &fnum, false);
+    fp = var2fpos(&argvars[0], true, &fnum, false, curwin);
   }
 
   if (fp != NULL) {
@@ -7665,39 +7651,33 @@ static void f_virtcol(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 {
   colnr_T vcol_start = 0;
   colnr_T vcol_end = 0;
-  switchwin_T switchwin;
+  win_T *wp = curwin;
-  bool winchanged = false;
 
   if (argvars[1].v_type != VAR_UNKNOWN && argvars[2].v_type != VAR_UNKNOWN) {
     // use the window specified in the third argument
     tabpage_T *tp;
-    win_T *wp = win_id2wp_tp((int)tv_get_number(&argvars[2]), &tp);
+    wp = win_id2wp_tp((int)tv_get_number(&argvars[2]), &tp);
     if (wp == NULL || tp == NULL) {
       goto theend;
     }
-
+    check_cursor(wp);
-    if (switch_win_noblock(&switchwin, wp, tp, true) != OK) {
-      goto theend;
-    }
-
-    check_cursor(curwin);
-    winchanged = true;
   }
 
-  int fnum = curbuf->b_fnum;
+  buf_T *bp = wp->w_buffer;
-  pos_T *fp = var2fpos(&argvars[0], false, &fnum, false);
+  int fnum = bp->b_fnum;
-  if (fp != NULL && fp->lnum <= curbuf->b_ml.ml_line_count
+  pos_T *fp = var2fpos(&argvars[0], false, &fnum, false, wp);
-      && fnum == curbuf->b_fnum) {
+  if (fp != NULL && fp->lnum <= bp->b_ml.ml_line_count
+      && fnum == bp->b_fnum) {
     // Limit the column to a valid value, getvvcol() doesn't check.
     if (fp->col < 0) {
       fp->col = 0;
     } else {
-      const colnr_T len = ml_get_len(fp->lnum);
+      const colnr_T len = ml_get_buf_len(bp, fp->lnum);
       if (fp->col > len) {
         fp->col = len;
       }
     }
-    getvvcol(curwin, fp, &vcol_start, NULL, &vcol_end);
+    getvvcol(wp, fp, &vcol_start, NULL, &vcol_end);
     vcol_start++;
     vcol_end++;
   }
@@ -7710,10 +7690,6 @@ theend:
   } else {
     rettv->vval.v_number = vcol_end;
   }
-
-  if (winchanged) {
-    restore_win_noblock(&switchwin, true);
-  }
 }
 
 /// "visualmode()" function

src/nvim/eval/typval.c

@@ -4229,7 +4229,7 @@ linenr_T tv_get_lnum(const typval_T *const tv)
   if (lnum <= 0 && did_emsg_before == did_emsg && tv->v_type != VAR_NUMBER) {
     int fnum;
     // No valid number, try using same function as line() does.
-    pos_T *const fp = var2fpos(tv, true, &fnum, false);
+    pos_T *const fp = var2fpos(tv, true, &fnum, false, curwin);
     if (fp != NULL) {
       lnum = fp->lnum;
     }

test/functional/ui/decorations_spec.lua

@@ -3571,6 +3571,42 @@ describe('extmark decorations', function()
       ]],
     })
   end)
+
+  it('line("w$", win) considers conceal_lines', function()
+    api.nvim_buf_set_lines(0, 0, -1, true, { 'line 1', 'line 2', 'line 3' })
+    api.nvim_buf_set_extmark(0, ns, 0, 0, { conceal_lines = '' }) -- conceal line 1
+
+    local win = exec_lua(function()
+      local provider_ns = vim.api.nvim_create_namespace('test_f_line')
+      _G.line_w_dollar = {}
+      vim.api.nvim_set_decoration_provider(provider_ns, {
+        on_start = function()
+          for _, win in ipairs(vim.api.nvim_tabpage_list_wins(0)) do
+            table.insert(_G.line_w_dollar, { win, vim.fn.line('w$', win) })
+          end
+        end,
+      })
+
+      local win = vim.api.nvim_open_win(0, false, {
+        relative = 'editor',
+        width = 20,
+        height = 1,
+        row = 0,
+        col = 0,
+        border = 'single',
+      })
+      vim.api.nvim_set_option_value('conceallevel', 2, { scope = 'local', win = win })
+
+      return win
+    end)
+
+    local line_w_dollar = exec_lua('return _G.line_w_dollar')
+    for _, win_line in ipairs(line_w_dollar) do
+      if win_line[1] == win then
+        eq(2, win_line[2])
+      end
+    end
+  end)
 end)
 
 describe('decorations: inline virtual text', function()