6 files changed, 58 insertions, 15 deletions
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 4aba1ec1bb..cae032f437 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -6709,7 +6709,6 @@ static int get_env_tv(char_u **arg, typval_T *rettv, int evaluate)
 # include "funcs.generated.h"
 #endif
 
-
 /*
  * Function given to ExpandGeneric() to obtain the list of internal
  * or user defined function names.
@@ -7712,26 +7711,47 @@ static void f_bufnr(typval_T *argvars, typval_T *rettv, FunPtr fptr)
     rettv->vval.v_number = -1;
 }
 
-/*
- * "bufwinnr(nr)" function
- */
-static void f_bufwinnr(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+static void buf_win_common(typval_T *argvars, typval_T *rettv, bool get_nr)
 {
-  (void)get_tv_number(&argvars[0]);         /* issue errmsg if type error */
-  ++emsg_off;
+  int error = false;
+  (void)get_tv_number_chk(&argvars[0], &error);  // issue errmsg if type error
+  if (error) {  // the argument has an invalid type
+    rettv->vval.v_number = -1;
+    return;
+  }
+
+  emsg_off++;
+  buf_T *buf = get_buf_tv(&argvars[0], true);
+  if (buf == NULL) {  // no need to search if buffer was not found
+    rettv->vval.v_number = -1;
+    goto end;
+  }
 
-  buf_T *buf = get_buf_tv(&argvars[0], TRUE);
   int winnr = 0;
+  int winid;
   bool found_buf = false;
   FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
-    ++winnr;
+    winnr++;
     if (wp->w_buffer == buf) {
       found_buf = true;
+      winid = wp->handle;
       break;
     }
   }
-  rettv->vval.v_number = (found_buf ? winnr : -1);
-  --emsg_off;
+  rettv->vval.v_number = (found_buf ? (get_nr ? winnr : winid) : -1);
+end:
+  emsg_off--;
+}
+
+/// "bufwinid(nr)" function
+static void f_bufwinid(typval_T *argvars, typval_T *rettv, FunPtr fptr) {
+  buf_win_common(argvars, rettv, false);
+}
+
+/// "bufwinnr(nr)" function
+static void f_bufwinnr(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  buf_win_common(argvars, rettv, true);
 }
 
 /*
@@ -10279,7 +10299,11 @@ find_win_by_nr (
   }
 
   FOR_ALL_WINDOWS_IN_TAB(wp, tp) {
-    if (--nr <= 0) {
+    if (nr >= LOWEST_WIN_ID) {
+      if (wp->handle == nr) {
+        return wp;
+      }
+    } else if (--nr <= 0) {
       return wp;
     }
   }
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index 984ccebbf8..eaaee81533 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -45,6 +45,7 @@ return {
     bufloaded={args=1},
     bufname={args=1},
     bufnr={args={1, 2}},
+    bufwinid={args=1},
     bufwinnr={args=1},
     byte2line={args=1},
     byteidx={args=2},
diff --git a/src/nvim/testdir/test_window_id.vim b/src/nvim/testdir/test_window_id.vim
index fa3ebd757e..66656e1d0a 100644
--- a/src/nvim/testdir/test_window_id.vim
+++ b/src/nvim/testdir/test_window_id.vim
@@ -3,17 +3,22 @@
 func Test_win_getid()
   edit one
   let id1 = win_getid()
+  let w:one = 'one'
   split two
   let id2 = win_getid()
   let bufnr2 = bufnr('%')
+  let w:two = 'two'
   split three
   let id3 = win_getid()
+  let w:three = 'three'
   tabnew
   edit four
   let id4 = win_getid()
+  let w:four = 'four'
   split five
   let id5 = win_getid()
   let bufnr5 = bufnr('%')
+  let w:five = 'five'
   tabnext
 
   wincmd w
@@ -28,6 +33,9 @@ func Test_win_getid()
   call assert_equal("three", expand("%"))
   call assert_equal(id3, win_getid())
   let nr3 = winnr()
+  call assert_equal('one', getwinvar(id1, 'one'))
+  call assert_equal('two', getwinvar(id2, 'two'))
+  call assert_equal('three', getwinvar(id3, 'three'))
   tabnext
   call assert_equal("five", expand("%"))
   call assert_equal(id5, win_getid())
@@ -36,7 +44,14 @@ func Test_win_getid()
   call assert_equal("four", expand("%"))
   call assert_equal(id4, win_getid())
   let nr4 = winnr()
+  call assert_equal('four', getwinvar(id4, 'four'))
+  call assert_equal('five', getwinvar(id5, 'five'))
+  call settabwinvar(1, id2, 'two', '2')
+  call setwinvar(id4, 'four', '4')
   tabnext
+  call assert_equal('4', gettabwinvar(2, id4, 'four'))
+  call assert_equal('five', gettabwinvar(2, id5, 'five'))
+  call assert_equal('2', getwinvar(id2, 'two'))
 
   exe nr1 . "wincmd w"
   call assert_equal(id1, win_getid())
diff --git a/src/nvim/version.c b/src/nvim/version.c
index f87064b408..e6ef600f8c 100644
--- a/src/nvim/version.c
+++ b/src/nvim/version.c
@@ -546,9 +546,9 @@ static int included_patches[] = {
   1898,
   // 1897,
   1896,
-  // 1895,
+  1895,
   // 1894 NA
-  // 1893,
+  1893,
   // 1892 NA
   // 1891 NA
   // 1890 NA
diff --git a/src/nvim/vim.h b/src/nvim/vim.h
index 09e9e850a7..6bbd9b58ef 100644
--- a/src/nvim/vim.h
+++ b/src/nvim/vim.h
@@ -316,4 +316,7 @@ enum {
 #define DIP_OPT 0x10    // also use "opt" directory in 'packpath'
 #define DIP_NORTP 0x20  // do not use 'runtimepath'
 
+// Lowest number used for window ID. Cannot have this many windows per tab.
+#define LOWEST_WIN_ID 1000
+
 #endif /* NVIM_VIM_H */
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 0be586c606..a259654d52 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -3694,7 +3694,7 @@ win_T *buf_jump_open_tab(buf_T *buf)
  */
 static win_T *win_alloc(win_T *after, int hidden)
 {
-  static int last_win_id = 0;
+  static int last_win_id = LOWEST_WIN_ID - 1;
 
   // allocate window structure and linesizes arrays
   win_T *new_wp = xcalloc(1, sizeof(win_T));