vim-patch:8.2.1727: a popup created with "cursorline" will ignore "firstline"

Problem:    A popup created with "cursorline" will ignore "firstline".
Solution:   When both "cursorline" and "firstline" are present put the cursor
            on "firstline". (closes vim/vim#7000)  Add the "winid" argument to
            getcurpos().
https://github.com/vim/vim/commit/99ca9c4868bb1669706b9e3de9a9218bd11cc459

Skip popup window related code.
Cherry-pick all of Test_getcurpos_setpos() from patch 8.2.0610.

3 files changed, 47 insertions, 12 deletions

diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index ef2b8a0cc0..8590614a0a 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -151,7 +151,7 @@ return {
     getcmdtype={},
     getcmdwintype={},
     getcompletion={args={2, 3}, base=1},
-    getcurpos={},
+    getcurpos={args={0, 1}, base=1},
     getcwd={args={0, 2}, base=1},
     getenv={args=1, base=1},
     getfontname={args={0, 1}},
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index b96ff50787..eb9c08c8f0 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -3845,37 +3845,45 @@ static void f_getpid(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
 static void getpos_both(typval_T *argvars, typval_T *rettv, bool getcurpos)
 {
-  pos_T *fp;
+  pos_T *fp = NULL;
+  win_T *wp = curwin;
   int fnum = -1;
 
   if (getcurpos) {
-    fp = &curwin->w_cursor;
+    if (argvars[0].v_type != VAR_UNKNOWN) {
+      wp = find_win_by_nr_or_id(&argvars[0]);
+      if (wp != NULL) {
+        fp = &wp->w_cursor;
+      }
+    } else {
+      fp = &curwin->w_cursor;
+    }
   } else {
     fp = var2fpos(&argvars[0], true, &fnum);
   }
 
   list_T *const l = tv_list_alloc_ret(rettv, 4 + (!!getcurpos));
   tv_list_append_number(l, (fnum != -1) ? (varnumber_T)fnum : (varnumber_T)0);
+  tv_list_append_number(l, ((fp != NULL) ? (varnumber_T)fp->lnum : (varnumber_T)0));
   tv_list_append_number(l, ((fp != NULL)
-                            ? (varnumber_T)fp->lnum
+                            ? (varnumber_T)(fp->col == MAXCOL ? MAXCOL : fp->col + 1)
                             : (varnumber_T)0));
-  tv_list_append_number(l, ((fp != NULL)
-          ? (varnumber_T)(fp->col == MAXCOL ? MAXCOL : fp->col + 1)
-                                            : (varnumber_T)0));
   tv_list_append_number(l, (fp != NULL) ? (varnumber_T)fp->coladd : (varnumber_T)0);
   if (getcurpos) {
     const int save_set_curswant = curwin->w_set_curswant;
     const colnr_T save_curswant = curwin->w_curswant;
     const colnr_T save_virtcol = curwin->w_virtcol;
 
-    update_curswant();
-    tv_list_append_number(l, (curwin->w_curswant == MAXCOL
-                              ? (varnumber_T)MAXCOL
-                              : (varnumber_T)curwin->w_curswant + 1));
+    if (wp == curwin) {
+      update_curswant();
+    }
+    tv_list_append_number(l, (wp == NULL) ? 0 : (wp->w_curswant == MAXCOL)
+                                                ? (varnumber_T)MAXCOL
+                                                : (varnumber_T)wp->w_curswant + 1);
 
     // Do not change "curswant", as it is unexpected that a get
     // function has a side effect.
-    if (save_set_curswant) {
+    if (wp == curwin && save_set_curswant) {
       curwin->w_set_curswant = save_set_curswant;
       curwin->w_curswant = save_curswant;
       curwin->w_virtcol = save_virtcol;
diff --git a/src/nvim/testdir/test_functions.vim b/src/nvim/testdir/test_functions.vim
index 42facdd491..6c2b0b97b6 100644
--- a/src/nvim/testdir/test_functions.vim
+++ b/src/nvim/testdir/test_functions.vim
@@ -1712,6 +1712,33 @@ func Test_nr2char()
   call assert_equal("\x80\xfc\b\xfd\x80\xfeX\x80\xfeX\x80\xfeX\x80\xfeX\x80\xfeX", eval('"\<M-' .. nr2char(0x40000000) .. '>"'))
 endfunc
 
+" Test for getcurpos() and setpos()
+func Test_getcurpos_setpos()
+  new
+  call setline(1, ['012345678', '012345678'])
+  normal gg6l
+  let sp = getcurpos()
+  normal 0
+  call setpos('.', sp)
+  normal jyl
+  call assert_equal('6', @")
+  call assert_equal(-1, setpos('.', v:_null_list))
+  call assert_equal(-1, setpos('.', {}))
+
+  let winid = win_getid()
+  normal G$
+  let pos = getcurpos()
+  wincmd w
+  call assert_equal(pos, getcurpos(winid))
+
+  wincmd w
+  close!
+
+  call assert_equal(getcurpos(), getcurpos(0))
+  call assert_equal([0, 0, 0, 0, 0], getcurpos(-1))
+  call assert_equal([0, 0, 0, 0, 0], getcurpos(1999))
+endfunc
+
 func HasDefault(msg = 'msg')
   return a:msg
 endfunc