patch 8.2.4487: Vim9: cannot compare with v:nullv8.2.4487

Problem:    Vim9: cannot compare with v:null.
Solution:   Allow comparing anything with v:null. (closes #9866)

9 files changed, 188 insertions, 19 deletions

diff --git a/src/evalvars.c b/src/evalvars.c
index 96d60a9595..862d5192bb 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -2816,30 +2816,34 @@ eval_variable(
 	    }
 
 	    // If a list or dict variable wasn't initialized, do it now.
-	    if (tv->v_type == VAR_DICT && tv->vval.v_dict == NULL)
+	    // Not for global variables, they are not declared.
+	    if (ht != &globvarht)
 	    {
-		tv->vval.v_dict = dict_alloc();
-		if (tv->vval.v_dict != NULL)
+		if (tv->v_type == VAR_DICT && tv->vval.v_dict == NULL)
 		{
-		    ++tv->vval.v_dict->dv_refcount;
-		    tv->vval.v_dict->dv_type = alloc_type(type);
+		    tv->vval.v_dict = dict_alloc();
+		    if (tv->vval.v_dict != NULL)
+		    {
+			++tv->vval.v_dict->dv_refcount;
+			tv->vval.v_dict->dv_type = alloc_type(type);
+		    }
 		}
-	    }
-	    else if (tv->v_type == VAR_LIST && tv->vval.v_list == NULL)
-	    {
-		tv->vval.v_list = list_alloc();
-		if (tv->vval.v_list != NULL)
+		else if (tv->v_type == VAR_LIST && tv->vval.v_list == NULL)
+		{
+		    tv->vval.v_list = list_alloc();
+		    if (tv->vval.v_list != NULL)
+		    {
+			++tv->vval.v_list->lv_refcount;
+			tv->vval.v_list->lv_type = alloc_type(type);
+		    }
+		}
+		else if (tv->v_type == VAR_BLOB && tv->vval.v_blob == NULL)
 		{
-		    ++tv->vval.v_list->lv_refcount;
-		    tv->vval.v_list->lv_type = alloc_type(type);
+		    tv->vval.v_blob = blob_alloc();
+		    if (tv->vval.v_blob != NULL)
+			++tv->vval.v_blob->bv_refcount;
 		}
 	    }
-	    else if (tv->v_type == VAR_BLOB && tv->vval.v_blob == NULL)
-	    {
-		tv->vval.v_blob = blob_alloc();
-		if (tv->vval.v_blob != NULL)
-		    ++tv->vval.v_blob->bv_refcount;
-	    }
 	    copy_tv(tv, rettv);
 	}
     }
diff --git a/src/proto/typval.pro b/src/proto/typval.pro
index f04bf1539a..b744bbcad1 100644
--- a/src/proto/typval.pro
+++ b/src/proto/typval.pro
@@ -57,6 +57,7 @@ int tv_check_lock(typval_T *tv, char_u *name, int use_gettext);
 void copy_tv(typval_T *from, typval_T *to);
 int typval_compare(typval_T *tv1, typval_T *tv2, exprtype_T type, int ic);
 int typval_compare_list(typval_T *tv1, typval_T *tv2, exprtype_T type, int ic, int *res);
+int typval_compare_null(typval_T *tv1, typval_T *tv2);
 int typval_compare_blob(typval_T *tv1, typval_T *tv2, exprtype_T type, int *res);
 int typval_compare_dict(typval_T *tv1, typval_T *tv2, exprtype_T type, int ic, int *res);
 int typval_compare_func(typval_T *tv1, typval_T *tv2, exprtype_T type, int ic, int *res);
diff --git a/src/testdir/test_vim9_disassemble.vim b/src/testdir/test_vim9_disassemble.vim
index 91464a7687..028e1a760e 100644
--- a/src/testdir/test_vim9_disassemble.vim
+++ b/src/testdir/test_vim9_disassemble.vim
@@ -1846,6 +1846,8 @@ def Test_disassemble_compare()
         ['true != isFalse', 'COMPAREBOOL !='],
         ['v:none == isNull', 'COMPARESPECIAL =='],
         ['v:none != isNull', 'COMPARESPECIAL !='],
+        ['"text" == isNull', 'COMPARENULL =='],
+        ['"text" != isNull', 'COMPARENULL !='],
 
         ['111 == aNumber', 'COMPARENR =='],
         ['111 != aNumber', 'COMPARENR !='],
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 4aad9c98c9..a38254f7dc 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -712,6 +712,81 @@ def Test_expr4_equal()
   unlet g:notReached
 enddef
 
+def Test_expr4_compare_null()
+  g:null_dict = test_null_dict()
+  g:not_null_list = []
+  var lines =<< trim END
+      assert_true(test_null_blob() == v:null)
+      assert_true(v:null == test_null_blob())
+      assert_false(test_null_blob() != v:null)
+      assert_false(v:null != test_null_blob())
+
+      if has('channel')
+        assert_true(test_null_channel() == v:null)
+        assert_true(v:null == test_null_channel())
+        assert_false(test_null_channel() != v:null)
+        assert_false(v:null != test_null_channel())
+      endif
+
+      assert_true(test_null_dict() == v:null)
+      assert_true(v:null == test_null_dict())
+      assert_false(test_null_dict() != v:null)
+      assert_false(v:null != test_null_dict())
+
+      assert_true(g:null_dict == v:null)
+      assert_true(v:null == g:null_dict)
+      assert_false(g:null_dict != v:null)
+      assert_false(v:null != g:null_dict)
+
+      assert_true(test_null_function() == v:null)
+      assert_true(v:null == test_null_function())
+      assert_false(test_null_function() != v:null)
+      assert_false(v:null != test_null_function())
+
+      if has('job')
+        assert_true(test_null_job() == v:null)
+        assert_true(v:null == test_null_job())
+        assert_false(test_null_job() != v:null)
+        assert_false(v:null != test_null_job())
+      endif
+
+      assert_true(test_null_list() == v:null)
+      assert_true(v:null == test_null_list())
+      assert_false(test_null_list() != v:null)
+      assert_false(v:null != test_null_list())
+
+      assert_false(g:not_null_list == v:null)
+      assert_false(v:null == g:not_null_list)
+      assert_true(g:not_null_list != v:null)
+      assert_true(v:null != g:not_null_list)
+
+      assert_true(test_null_partial() == v:null)
+      assert_true(v:null == test_null_partial())
+      assert_false(test_null_partial() != v:null)
+      assert_false(v:null != test_null_partial())
+
+      assert_true(test_null_string() == v:null)
+      assert_true(v:null == test_null_string())
+      assert_false(test_null_string() != v:null)
+      assert_false(v:null != test_null_string())
+  END
+  v9.CheckDefAndScriptSuccess(lines)
+  unlet g:null_dict
+  unlet g:not_null_list
+
+  v9.CheckDefAndScriptFailure(['echo 123 == v:null'], 'E1072: Cannot compare number with special')
+  v9.CheckDefAndScriptFailure(['echo v:null == 123'], 'E1072: Cannot compare special with number')
+  v9.CheckDefAndScriptFailure(['echo 123 != v:null'], 'E1072: Cannot compare number with special')
+  v9.CheckDefAndScriptFailure(['echo v:null != 123'], 'E1072: Cannot compare special with number')
+  v9.CheckDefAndScriptFailure(['echo true == v:null'], 'E1072: Cannot compare bool with special')
+  v9.CheckDefAndScriptFailure(['echo v:null == true'], 'E1072: Cannot compare special with bool')
+  v9.CheckDefAndScriptFailure(['echo true != v:null'], 'E1072: Cannot compare bool with special')
+  v9.CheckDefAndScriptFailure(['echo v:null != true'], 'E1072: Cannot compare special with bool')
+  v9.CheckDefAndScriptFailure(['echo false == v:null'], 'E1072: Cannot compare bool with special')
+
+  v9.CheckDefExecAndScriptFailure(['echo [] == v:none'], ['E1072: Cannot compare list with special', 'E691: Can only compare List with List'])
+enddef
+
 def Test_expr4_wrong_type()
   for op in ['>', '>=', '<', '<=', '=~', '!~']
     v9.CheckDefExecAndScriptFailure([
diff --git a/src/typval.c b/src/typval.c
index ab226403df..775466784d 100644
--- a/src/typval.c
+++ b/src/typval.c
@@ -1169,6 +1169,21 @@ typval_compare(
 	// it means TRUE.
 	n1 = (type == EXPR_ISNOT);
     }
+    else if (((tv1->v_type == VAR_SPECIAL && tv1->vval.v_number == VVAL_NULL)
+		|| (tv2->v_type == VAR_SPECIAL
+					   && tv2->vval.v_number == VVAL_NULL))
+	    && tv1->v_type != tv2->v_type
+	    && (type == EXPR_EQUAL || type == EXPR_NEQUAL))
+    {
+	n1 = typval_compare_null(tv1, tv2);
+	if (n1 == MAYBE)
+	{
+	    clear_tv(tv1);
+	    return FAIL;
+	}
+	if (type == EXPR_NEQUAL)
+	    n1 = !n1;
+    }
     else if (tv1->v_type == VAR_BLOB || tv2->v_type == VAR_BLOB)
     {
 	if (typval_compare_blob(tv1, tv2, type, &res) == FAIL)
@@ -1366,6 +1381,35 @@ typval_compare_list(
 }
 
 /*
+ * Compare v:null/v:none with another type.  Return TRUE if the value is NULL.
+ */
+    int
+typval_compare_null(typval_T *tv1, typval_T *tv2)
+{
+    if ((tv1->v_type == VAR_SPECIAL && tv1->vval.v_number == VVAL_NULL)
+	    || (tv2->v_type == VAR_SPECIAL && tv2->vval.v_number == VVAL_NULL))
+    {
+	typval_T	*tv = tv1->v_type == VAR_SPECIAL ? tv2 : tv1;
+
+	switch (tv->v_type)
+	{
+	    case VAR_BLOB: return tv->vval.v_blob == NULL;
+	    case VAR_CHANNEL: return tv->vval.v_channel == NULL;
+	    case VAR_DICT: return tv->vval.v_dict == NULL;
+	    case VAR_FUNC: return tv->vval.v_string == NULL;
+	    case VAR_JOB: return tv->vval.v_job == NULL;
+	    case VAR_LIST: return tv->vval.v_list == NULL;
+	    case VAR_PARTIAL: return tv->vval.v_partial == NULL;
+	    case VAR_STRING: return tv->vval.v_string == NULL;
+	    default: break;
+	}
+    }
+    semsg(_(e_cannot_compare_str_with_str),
+			 vartype_name(tv1->v_type), vartype_name(tv2->v_type));
+    return MAYBE;
+}
+
+/*
  * Compare "tv1" to "tv2" as blobs acording to "type".
  * Put the result, false or true, in "res".
  * Return FAIL and give an error message when the comparison can't be done.
diff --git a/src/version.c b/src/version.c
index e563142a16..960e18cea8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4487,
+/**/
     4486,
 /**/
     4485,
diff --git a/src/vim9.h b/src/vim9.h
index 87ee6b163f..07dd6392f3 100644
--- a/src/vim9.h
+++ b/src/vim9.h
@@ -134,6 +134,7 @@ typedef enum {
     // comparative operations; isn_arg.op.op_type is exprtype_T, op_ic used
     ISN_COMPAREBOOL,
     ISN_COMPARESPECIAL,
+    ISN_COMPARENULL,
     ISN_COMPARENR,
     ISN_COMPAREFLOAT,
     ISN_COMPARESTRING,
diff --git a/src/vim9execute.c b/src/vim9execute.c
index a7b76c639e..56220f862e 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -3880,6 +3880,25 @@ exec_instructions(ectx_T *ectx)
 		}
 		break;
 
+	    case ISN_COMPARENULL:
+		{
+		    typval_T	*tv1 = STACK_TV_BOT(-2);
+		    typval_T	*tv2 = STACK_TV_BOT(-1);
+		    int		res;
+
+		    res = typval_compare_null(tv1, tv2);
+		    if (res == MAYBE)
+			goto on_error;
+		    if (iptr->isn_arg.op.op_type == EXPR_NEQUAL)
+			res = !res;
+		    clear_tv(tv1);
+		    clear_tv(tv2);
+		    --ectx->ec_stack.ga_len;
+		    tv1->v_type = VAR_BOOL;
+		    tv1->vval.v_number = res ? VVAL_TRUE : VVAL_FALSE;
+		}
+		break;
+
 	    // Operation with two number arguments
 	    case ISN_OPNR:
 	    case ISN_COMPARENR:
@@ -5901,6 +5920,7 @@ list_instructions(char *pfx, isn_T *instr, int instr_count, ufunc_T *ufunc)
 
 	    case ISN_COMPAREBOOL:
 	    case ISN_COMPARESPECIAL:
+	    case ISN_COMPARENULL:
 	    case ISN_COMPARENR:
 	    case ISN_COMPAREFLOAT:
 	    case ISN_COMPARESTRING:
@@ -5936,6 +5956,7 @@ list_instructions(char *pfx, isn_T *instr, int instr_count, ufunc_T *ufunc)
 			   case ISN_COMPAREBOOL: type = "COMPAREBOOL"; break;
 			   case ISN_COMPARESPECIAL:
 						 type = "COMPARESPECIAL"; break;
+			   case ISN_COMPARENULL: type = "COMPARENULL"; break;
 			   case ISN_COMPARENR: type = "COMPARENR"; break;
 			   case ISN_COMPAREFLOAT: type = "COMPAREFLOAT"; break;
 			   case ISN_COMPARESTRING:
diff --git a/src/vim9instr.c b/src/vim9instr.c
index 9116f4111c..2c76fadc3a 100644
--- a/src/vim9instr.c
+++ b/src/vim9instr.c
@@ -372,6 +372,24 @@ get_compare_isn(exprtype_T exprtype, vartype_T type1, vartype_T type2)
 	    || ((type1 == VAR_NUMBER || type1 == VAR_FLOAT)
 	      && (type2 == VAR_NUMBER || type2 == VAR_FLOAT)))
 	isntype = ISN_COMPAREANY;
+    else if (type1 == VAR_SPECIAL || type2 == VAR_SPECIAL)
+    {
+	switch (type1 == VAR_SPECIAL ? type2 : type1)
+	{
+	    case VAR_BLOB: break;
+	    case VAR_CHANNEL: break;
+	    case VAR_DICT: break;
+	    case VAR_FUNC: break;
+	    case VAR_JOB: break;
+	    case VAR_LIST: break;
+	    case VAR_PARTIAL: break;
+	    case VAR_STRING: break;
+	    default: semsg(_(e_cannot_compare_str_with_str),
+				   vartype_name(type1), vartype_name(type2));
+		     return ISN_DROP;
+	}
+	isntype = ISN_COMPARENULL;
+    }
 
     if ((exprtype == EXPR_IS || exprtype == EXPR_ISNOT)
 	    && (isntype == ISN_COMPAREBOOL
@@ -388,7 +406,7 @@ get_compare_isn(exprtype_T exprtype, vartype_T type1, vartype_T type2)
 		    && (type1 == VAR_BOOL || type1 == VAR_SPECIAL
 		       || type2 == VAR_BOOL || type2 == VAR_SPECIAL)))
 	    || ((exprtype != EXPR_EQUAL && exprtype != EXPR_NEQUAL
-				 && exprtype != EXPR_IS && exprtype != EXPR_ISNOT
+			       && exprtype != EXPR_IS && exprtype != EXPR_ISNOT
 		    && (type1 == VAR_BLOB || type2 == VAR_BLOB
 			|| type1 == VAR_LIST || type2 == VAR_LIST))))
     {
@@ -2131,6 +2149,7 @@ delete_instr(isn_T *isn)
 	case ISN_COMPAREFUNC:
 	case ISN_COMPARELIST:
 	case ISN_COMPARENR:
+	case ISN_COMPARENULL:
 	case ISN_COMPARESPECIAL:
 	case ISN_COMPARESTRING:
 	case ISN_CONCAT: