vim-patch:8.2.0619: null dict is not handled like an empty dict

Problem:    Null dict is not handled like an empty dict.
Solution:   Fix the code and add tests. (Yegappan Lakshmanan, closes vim/vim#5968)

https://github.com/vim/vim/commit/ea04a6e8baff2f27da7cdd54bf70a5525994f76d

Nvim doesn't support modifying NULL list, so comment out a line.

10 files changed, 72 insertions, 24 deletions

diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 69bc26b82e..ffbe66aa25 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -1449,6 +1449,7 @@ char *get_lval(char *const name, typval_T *const rettv, lval_T *const lp, const
           key[len] = prevval;
         }
         if (wrong) {
+          tv_clear(&var1);
           return NULL;
         }
       }
diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index a6a8c16a3b..3b513bfafb 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -2490,10 +2490,14 @@ bool tv_dict_equal(dict_T *const d1, dict_T *const d2, const bool ic, const bool
   if (d1 == d2) {
     return true;
   }
-  if (d1 == NULL || d2 == NULL) {
+  if (tv_dict_len(d1) != tv_dict_len(d2)) {
     return false;
   }
-  if (tv_dict_len(d1) != tv_dict_len(d2)) {
+  if (tv_dict_len(d1) == 0) {
+    // empty and NULL dicts are considered equal
+    return true;
+  }
+  if (d1 == NULL || d2 == NULL) {
     return false;
   }
 
diff --git a/src/nvim/testdir/test_blob.vim b/src/nvim/testdir/test_blob.vim
index f2b32c06d4..c5a217f36f 100644
--- a/src/nvim/testdir/test_blob.vim
+++ b/src/nvim/testdir/test_blob.vim
@@ -209,6 +209,7 @@ func Test_blob_add()
   call assert_equal(0z001122, b)
   call add(b, '51')
   call assert_equal(0z00112233, b)
+  call assert_equal(1, add(v:_null_blob, 0x22))
 
   call assert_fails('call add(b, [9])', 'E745:')
   call assert_fails('call add("", 0x01)', 'E897:')
diff --git a/src/nvim/testdir/test_expr.vim b/src/nvim/testdir/test_expr.vim
index f6e6004a31..66660ab75e 100644
--- a/src/nvim/testdir/test_expr.vim
+++ b/src/nvim/testdir/test_expr.vim
@@ -99,13 +99,6 @@ func Test_loop_over_null_list()
   endfor
 endfunc
 
-func Test_compare_null_dict()
-  call assert_fails('let x = v:_null_dict[10]')
-  call assert_equal({}, {})
-  call assert_equal(v:_null_dict, v:_null_dict)
-  call assert_notequal({}, v:_null_dict)
-endfunc
-
 func Test_set_reg_null_list()
   call setreg('x', v:_null_list)
 endfunc
diff --git a/src/nvim/testdir/test_filter_map.vim b/src/nvim/testdir/test_filter_map.vim
index 54f6e269e0..ebcb6699c6 100644
--- a/src/nvim/testdir/test_filter_map.vim
+++ b/src/nvim/testdir/test_filter_map.vim
@@ -88,6 +88,7 @@ func Test_map_filter_fails()
   call assert_fails("let l = filter('abc', '\"> \" . v:val')", 'E896:')
   call assert_fails("let l = filter([1, 2, 3], '{}')", 'E728:')
   call assert_fails("let l = filter({'k' : 10}, '{}')", 'E728:')
+  call assert_fails("let l = filter([1, 2], {})", 'E731:')
   call assert_equal(0, map(v:_null_list, '"> " .. v:val'))
   call assert_equal(0, map(v:_null_dict, '"> " .. v:val'))
 endfunc
diff --git a/src/nvim/testdir/test_let.vim b/src/nvim/testdir/test_let.vim
index 89cf4b5498..937076aa2a 100644
--- a/src/nvim/testdir/test_let.vim
+++ b/src/nvim/testdir/test_let.vim
@@ -275,6 +275,7 @@ func Test_let_errors()
   call assert_fails('let &buftype[1] = "nofile"', 'E18:')
   let s = "var"
   let var = 1
+  call assert_fails('let var += [1,2]', 'E734:')
   call assert_fails('let {s}.1 = 2', 'E18:')
   call assert_fails('let a[1] = 5', 'E121:')
   let l = [[1,2]]
@@ -287,6 +288,8 @@ func Test_let_errors()
   call assert_fails('let l[0:1] = [1, 2, 3]', 'E710:')
   call assert_fails('let l[-2:-3] = [3, 4]', 'E684:')
   call assert_fails('let l[0:4] = [5, 6]', 'E711:')
+  call assert_fails('let g:["a;b"] = 10', 'E461:')
+  call assert_fails('let g:.min = function("max")', 'E704:')
 
   " This test works only when the language is English
   if v:lang == "C" || v:lang =~ '^[Ee]n'
diff --git a/src/nvim/testdir/test_listdict.vim b/src/nvim/testdir/test_listdict.vim
index d92563a451..f7261b2055 100644
--- a/src/nvim/testdir/test_listdict.vim
+++ b/src/nvim/testdir/test_listdict.vim
@@ -32,7 +32,11 @@ func Test_list_slice()
   call assert_equal([1, 'as''d', [1, 2, function('strlen')], {'a': 1}], l[0:8])
   call assert_equal([], l[8:-1])
   call assert_equal([], l[0:-10])
-  call assert_equal([], v:_null_list[:2])
+  " perform an operation on a list slice
+  let l = [1, 2, 3]
+  let l[:1] += [1, 2]
+  let l[2:] -= [1]
+  call assert_equal([2, 4, 2], l)
 endfunc
 
 " List identity
@@ -147,6 +151,20 @@ func Test_list_func_remove()
   call assert_fails("call remove(l, l)", 'E745:')
 endfunc
 
+" List add() function
+func Test_list_add()
+  let l = []
+  call add(l, 1)
+  call add(l, [2, 3])
+  call add(l, [])
+  call add(l, v:_null_list)
+  call add(l, {'k' : 3})
+  call add(l, {})
+  call add(l, v:_null_dict)
+  call assert_equal([1, [2, 3], [], [], {'k' : 3}, {}, {}], l)
+  " call assert_equal(1, add(v:_null_list, 4))
+endfunc
+
 " Tests for Dictionary type
 
 func Test_dict()
@@ -660,8 +678,6 @@ func Test_reverse_sort_uniq()
   call assert_fails("call sort([1, 2], function('min'), 1)", "E715:")
   call assert_fails("call sort([1, 2], function('invalid_func'))", "E700:")
   call assert_fails("call sort([1, 2], function('min'))", "E702:")
-  call assert_equal(0, sort(v:_null_list))
-  call assert_equal(0, uniq(v:_null_list))
 endfunc
 
 " reduce a list or a blob
@@ -709,7 +725,7 @@ func Test_reduce()
   call assert_equal(42, reduce(v:_null_blob, function('add'), 42))
 endfunc
 
-" splitting a string to a List
+" splitting a string to a List using split()
 func Test_str_split()
   call assert_equal(['aa', 'bb'], split('  aa  bb '))
   call assert_equal(['aa', 'bb'], split('  aa  bb  ', '\W\+', 0))
@@ -964,6 +980,11 @@ func Test_listdict_index()
   call assert_fails("let l = insert([1,2,3], 4, 10)", 'E684:')
   call assert_fails("let l = insert([1,2,3], 4, -10)", 'E684:')
   call assert_fails("let l = insert([1,2,3], 4, [])", 'E745:')
+  let l = [1, 2, 3]
+  call assert_fails("let l[i] = 3", 'E121:')
+  call assert_fails("let l[1.1] = 4", 'E806:')
+  call assert_fails("let l[:i] = [4, 5]", 'E121:')
+  call assert_fails("let l[:3.2] = [4, 5]", 'E806:')
 endfunc
 
 " Test for a null list
@@ -1005,12 +1026,18 @@ endfunc
 
 " Test for a null dict
 func Test_null_dict()
-  call assert_equal(0, items(v:_null_dict))
-  call assert_equal(0, keys(v:_null_dict))
-  call assert_equal(0, values(v:_null_dict))
-  call assert_false(has_key(v:_null_dict, 'k'))
-  call assert_fails("let l = [] + v:_null_list", 'E15:')
-  call assert_fails("let l = v:_null_list + []", 'E15:')
+  call assert_equal(v:_null_dict, v:_null_dict)
+  let d = v:_null_dict
+  call assert_equal({}, d)
+  call assert_equal(0, len(d))
+  call assert_equal(1, empty(d))
+  call assert_equal(0, items(d))
+  call assert_equal(0, keys(d))
+  call assert_equal(0, values(d))
+  call assert_false(has_key(d, 'k'))
+  call assert_equal('{}', string(d))
+  call assert_fails('let x = v:_null_dict[10]')
+  call assert_equal({}, {})
 endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/nvim/testdir/test_unlet.vim b/src/nvim/testdir/test_unlet.vim
index acf98bb1fc..4779d17906 100644
--- a/src/nvim/testdir/test_unlet.vim
+++ b/src/nvim/testdir/test_unlet.vim
@@ -27,6 +27,7 @@ func Test_unlet_fails()
   call assert_fails("unlet l['k'", 'E111:')
   let d = {'k' : 1}
   call assert_fails("unlet d.k2", 'E716:')
+  call assert_fails("unlet {a};", 'E488:')
 endfunc
 
 func Test_unlet_env()
diff --git a/src/nvim/testdir/test_usercommands.vim b/src/nvim/testdir/test_usercommands.vim
index a3070d6517..5b8b384bae 100644
--- a/src/nvim/testdir/test_usercommands.vim
+++ b/src/nvim/testdir/test_usercommands.vim
@@ -623,17 +623,17 @@ func Test_usercmd_custom()
     return "a\nb\n"
   endfunc
   command -nargs=* -complete=customlist,T1 TCmd1
-  call feedkeys(":T1 \<C-A>\<C-B>\"\<CR>", 'xt')
-  call assert_equal('"T1 ', @:)
+  call feedkeys(":TCmd1 \<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"TCmd1 ', @:)
   delcommand TCmd1
   delfunc T1
 
   func T2(a, c, p)
-    return ['a', 'b', 'c']
+    return {}
   endfunc
   command -nargs=* -complete=customlist,T2 TCmd2
-  call feedkeys(":T2 \<C-A>\<C-B>\"\<CR>", 'xt')
-  call assert_equal('"T2 ', @:)
+  call feedkeys(":TCmd2 \<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"TCmd2 ', @:)
   delcommand TCmd2
   delfunc T2
 endfunc
diff --git a/src/nvim/testdir/test_vimscript.vim b/src/nvim/testdir/test_vimscript.vim
index 3d3f0a8839..a9fd7a4bef 100644
--- a/src/nvim/testdir/test_vimscript.vim
+++ b/src/nvim/testdir/test_vimscript.vim
@@ -1658,6 +1658,20 @@ func Test_compound_assignment_operators()
       call assert_fails('let x .= "f"', 'E734')
       let x = !3.14
       call assert_equal(0.0, x)
+
+      " integer and float operations
+      let x = 1
+      let x *= 2.1
+      call assert_equal(2.1, x)
+      let x = 1
+      let x /= 0.25
+      call assert_equal(4.0, x)
+      let x = 1
+      call assert_fails('let x %= 0.25', 'E734:')
+      let x = 1
+      call assert_fails('let x .= 0.25', 'E734:')
+      let x = 1.0
+      call assert_fails('let x += [1.1]', 'E734:')
     endif
 
     " Test for environment variable
@@ -1839,6 +1853,9 @@ func Test_missing_end()
 
   " Missing 'in' in a :for statement
   call assert_fails('for i range(1) | endfor', 'E690:')
+
+  " Incorrect number of variables in for
+  call assert_fails('for [i,] in range(3) | endfor', 'E475:')
 endfunc
 
 " Test for deep nesting of if/for/while/try statements              {{{1