patch 8.2.2533: Vim9: cannot use a range with :unlet

Problem:    Vim9: cannot use a range with :unlet.
Solution:   Implement ISN_UNLETRANGE.

src/errors.h

@@ -365,3 +365,7 @@ EXTERN char e_variable_nr_type_mismatch_expected_str_but_got_str[]
 	INIT(= N_("E1163: Variable %d: type mismatch, expected %s but got %s"));
 EXTERN char e_vim9cmd_must_be_followed_by_command[]
 	INIT(= N_("E1164: vim9cmd must be followed by a command"));
+EXTERN char e_cannot_use_range_with_assignment_str[]
+	INIT(= N_("E1165: Cannot use a range with an assignment: %s"));
+EXTERN char e_cannot_use_range_with_dictionary[]
+	INIT(= N_("E1166: Cannot use a range with a dictionary"));

src/eval.c

@@ -1213,15 +1213,7 @@ get_lval(
 
 	    lp->ll_dict = NULL;
 	    lp->ll_list = lp->ll_tv->vval.v_list;
-	    lp->ll_li = list_find(lp->ll_list, lp->ll_n1);
-	    if (lp->ll_li == NULL)
-	    {
-		if (lp->ll_n1 < 0)
-		{
-		    lp->ll_n1 = 0;
-		    lp->ll_li = list_find(lp->ll_list, lp->ll_n1);
-		}
-	    }
+	    lp->ll_li = list_find_index(lp->ll_list, &lp->ll_n1);
 	    if (lp->ll_li == NULL)
 	    {
 		clear_tv(&var2);

src/evalvars.c

@@ -1656,27 +1656,9 @@ do_unlet_var(
 	return FAIL;
     else if (lp->ll_range)
     {
-	listitem_T    *li;
-	listitem_T    *ll_li = lp->ll_li;
-	int	      ll_n1 = lp->ll_n1;
-
-	while (ll_li != NULL && (lp->ll_empty2 || lp->ll_n2 >= ll_n1))
-	{
-	    li = ll_li->li_next;
-	    if (value_check_lock(ll_li->li_tv.v_lock, lp->ll_name, FALSE))
-		return FAIL;
-	    ll_li = li;
-	    ++ll_n1;
-	}
-
-	// Delete a range of List items.
-	while (lp->ll_li != NULL && (lp->ll_empty2 || lp->ll_n2 >= lp->ll_n1))
-	{
-	    li = lp->ll_li->li_next;
-	    listitem_remove(lp->ll_list, lp->ll_li);
-	    lp->ll_li = li;
-	    ++lp->ll_n1;
-	}
+	if (list_unlet_range(lp->ll_list, lp->ll_li, lp->ll_name, lp->ll_n1,
+					   !lp->ll_empty2, lp->ll_n2) == FAIL)
+	    return FAIL;
     }
     else
     {
@@ -1691,6 +1673,43 @@ do_unlet_var(
     return ret;
 }
 
+/*
+ * Unlet one item or a range of items from a list.
+ * Return OK or FAIL.
+ */
+    int
+list_unlet_range(
+	list_T	    *l,
+	listitem_T  *li_first,
+	char_u	    *name,
+	long	    n1_arg,
+	int	    has_n2,
+	long	    n2)
+{
+    listitem_T  *li = li_first;
+    int		n1 = n1_arg;
+
+    while (li != NULL && (!has_n2 || n2 >= n1))
+    {
+	if (value_check_lock(li->li_tv.v_lock, name, FALSE))
+	    return FAIL;
+	li = li->li_next;
+	++n1;
+    }
+
+    // Delete a range of List items.
+    li = li_first;
+    n1 = n1_arg;
+    while (li != NULL && (!has_n2 || n2 >= n1))
+    {
+	listitem_T *next = li->li_next;
+
+	listitem_remove(l, li);
+	li = next;
+	++n1;
+    }
+    return OK;
+}
 /*
  * "unlet" a variable.  Return OK if it existed, FAIL if not.
  * When "forceit" is TRUE don't complain if the variable doesn't exist.

src/list.c

@@ -530,6 +530,26 @@ list_find_str(list_T *l, long idx)
     return tv_get_string(&li->li_tv);
 }
 
+/*
+ * Like list_find() but when a negative index is used that is not found use
+ * zero and set "idx" to zero.  Used for first index of a range.
+ */
+    listitem_T *
+list_find_index(list_T *l, long *idx)
+{
+    listitem_T *li = list_find(l, *idx);
+
+    if (li == NULL)
+    {
+	if (*idx < 0)
+	{
+	    *idx = 0;
+	    li = list_find(l, *idx);
+	}
+    }
+    return li;
+}
+
 /*
  * Locate "item" list "l" and return its index.
  * Returns -1 when "item" is not in the list.

src/proto/evalvars.pro

@@ -23,6 +23,7 @@ void list_hashtable_vars(hashtab_T *ht, char *prefix, int empty, int *first);
 void ex_unlet(exarg_T *eap);
 void ex_lockvar(exarg_T *eap);
 void ex_unletlock(exarg_T *eap, char_u *argstart, int deep, int glv_flags, int (*callback)(lval_T *, char_u *, exarg_T *, int, void *), void *cookie);
+int list_unlet_range(list_T *l, listitem_T *li_first, char_u *name, long n1_arg, int has_n2, long n2);
 int do_unlet(char_u *name, int forceit);
 void item_lock(typval_T *tv, int deep, int lock, int check_refcount);
 void del_menutrans_vars(void);

src/proto/list.pro

@@ -20,6 +20,7 @@ int list_equal(list_T *l1, list_T *l2, int ic, int recursive);
 listitem_T *list_find(list_T *l, long n);
 long list_find_nr(list_T *l, long idx, int *errorp);
 char_u *list_find_str(list_T *l, long idx);
+listitem_T *list_find_index(list_T *l, long *idx);
 long list_idx_of_item(list_T *l, listitem_T *item);
 void list_append(list_T *l, listitem_T *item);
 int list_append_tv(list_T *l, typval_T *tv);

src/testdir/test_vim9_assign.vim

@@ -9,6 +9,7 @@ let g:existing = 'yes'
 let g:inc_counter = 1
 let $SOME_ENV_VAR = 'some'
 let g:alist = [7]
+let g:adict = #{a: 1}
 let g:astring = 'text'
 
 def Test_assignment_bool()
@@ -1414,6 +1415,51 @@ def Test_unlet()
   unlet ll[-1]
   assert_equal([1, 3], ll)
 
+  ll = [1, 2, 3, 4]
+  unlet ll[0 : 1]
+  assert_equal([3, 4], ll)
+
+  ll = [1, 2, 3, 4]
+  unlet ll[2 : 8]
+  assert_equal([1, 2], ll)
+
+  ll = [1, 2, 3, 4]
+  unlet ll[-2 : -1]
+  assert_equal([1, 2], ll)
+
+  CheckDefFailure([
+    'var ll = [1, 2]',
+    'll[1 : 2] = 7',
+    ], 'E1165:', 2)
+  CheckDefFailure([
+    'var dd = {a: 1}',
+    'unlet dd["a" : "a"]',
+    ], 'E1166:', 2)
+  CheckDefExecFailure([
+    'unlet g:adict[0 : 1]',
+    ], 'E1148:', 1)
+  CheckDefFailure([
+    'var ll = [1, 2]',
+    'unlet ll[0:1]',
+    ], 'E1004:', 2)
+  CheckDefFailure([
+    'var ll = [1, 2]',
+    'unlet ll[0 :1]',
+    ], 'E1004:', 2)
+  CheckDefFailure([
+    'var ll = [1, 2]',
+    'unlet ll[0: 1]',
+    ], 'E1004:', 2)
+
+  CheckDefFailure([
+    'var ll = [1, 2]',
+    'unlet ll["x" : 1]',
+    ], 'E1012:', 2)
+  CheckDefFailure([
+    'var ll = [1, 2]',
+    'unlet ll[0 : "x"]',
+    ], 'E1012:', 2)
+
   # list of dict unlet
   var dl = [{a: 1, b: 2}, {c: 3}]
   unlet dl[0]['b']

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2533,
 /**/
     2532,
 /**/

src/vim9.h

@@ -61,6 +61,7 @@ typedef enum {
     ISN_UNLET,		// unlet variable isn_arg.unlet.ul_name
     ISN_UNLETENV,	// unlet environment variable isn_arg.unlet.ul_name
     ISN_UNLETINDEX,	// unlet item of list or dict
+    ISN_UNLETRANGE,	// unlet items of list
 
     ISN_LOCKCONST,	// lock constant value
 

src/vim9compile.c

@@ -5865,6 +5865,7 @@ compile_assign_unlet(
     vartype_T	dest_type;
     size_t	varlen = lhs->lhs_varlen;
     garray_T    *stack = &cctx->ctx_type_stack;
+    int		range = FALSE;
 
     // Compile the "idx" in "var[idx]" or "key" in "var.key".
     p = var_start + varlen;
@@ -5872,6 +5873,27 @@ compile_assign_unlet(
     {
 	p = skipwhite(p + 1);
 	r = compile_expr0(&p, cctx);
+
+	if (r == OK && *skipwhite(p) == ':')
+	{
+	    // unlet var[idx : idx]
+	    if (is_assign)
+	    {
+		semsg(_(e_cannot_use_range_with_assignment_str), p);
+		return FAIL;
+	    }
+	    range = TRUE;
+	    p = skipwhite(p);
+	    if (!IS_WHITE_OR_NUL(p[-1]) || !IS_WHITE_OR_NUL(p[1]))
+	    {
+		semsg(_(e_white_space_required_before_and_after_str_at_str),
+								      ":", p);
+		return FAIL;
+	    }
+	    p = skipwhite(p + 1);
+	    r = compile_expr0(&p, cctx);
+	}
+
 	if (r == OK && *skipwhite(p) != ']')
 	{
 	    // this should not happen
@@ -5897,17 +5919,29 @@ compile_assign_unlet(
     else
     {
 	dest_type = lhs->lhs_type->tt_type;
+	if (dest_type == VAR_DICT && range)
+	{
+	    emsg(e_cannot_use_range_with_dictionary);
+	    return FAIL;
+	}
 	if (dest_type == VAR_DICT && may_generate_2STRING(-1, cctx) == FAIL)
 	    return FAIL;
-	if (dest_type == VAR_LIST
-		&& need_type(((type_T **)stack->ga_data)[stack->ga_len - 1],
+	if (dest_type == VAR_LIST)
+	{
+	    if (range
+		  && need_type(((type_T **)stack->ga_data)[stack->ga_len - 2],
 				 &t_number, -1, 0, cctx, FALSE, FALSE) == FAIL)
-	    return FAIL;
+		return FAIL;
+	    if (need_type(((type_T **)stack->ga_data)[stack->ga_len - 1],
+				 &t_number, -1, 0, cctx, FALSE, FALSE) == FAIL)
+		return FAIL;
+	}
     }
 
     // Load the dict or list.  On the stack we then have:
     // - value (for assignment, not for :unlet)
     // - index
+    // - for [a : b] second index
     // - variable
     if (lhs->lhs_dest == dest_expr)
     {
@@ -5946,6 +5980,11 @@ compile_assign_unlet(
 		return FAIL;
 	    isn->isn_arg.vartype = dest_type;
 	}
+	else if (range)
+	{
+	    if (generate_instr_drop(cctx, ISN_UNLETRANGE, 3) == NULL)
+		return FAIL;
+	}
 	else
 	{
 	    if (generate_instr_drop(cctx, ISN_UNLETINDEX, 2) == NULL)
@@ -8907,6 +8946,7 @@ delete_instr(isn_T *isn)
 	case ISN_TRY:
 	case ISN_TRYCONT:
 	case ISN_UNLETINDEX:
+	case ISN_UNLETRANGE:
 	case ISN_UNPACK:
 	    // nothing allocated
 	    break;

src/vim9execute.c

@@ -878,6 +878,21 @@ error_if_locked(int lock, char *error)
     return FALSE;
 }
 
+/*
+ * Give an error if "tv" is not a number and return FAIL.
+ */
+    static int
+check_for_number(typval_T *tv)
+{
+    if (tv->v_type != VAR_NUMBER)
+    {
+	semsg(_(e_expected_str_but_got_str),
+		vartype_name(VAR_NUMBER), vartype_name(tv->v_type));
+	return FAIL;
+    }
+    return OK;
+}
+
 /*
  * Store "tv" in variable "name".
  * This is for s: and g: variables.
@@ -2178,12 +2193,9 @@ call_def_function(
 		    else if (tv_dest->v_type == VAR_LIST)
 		    {
 			// unlet a List item, index must be a number
-			if (tv_idx->v_type != VAR_NUMBER)
+			SOURCING_LNUM = iptr->isn_lnum;
+			if (check_for_number(tv_idx) == FAIL)
 			{
-			    SOURCING_LNUM = iptr->isn_lnum;
-			    semsg(_(e_expected_str_but_got_str),
-					vartype_name(VAR_NUMBER),
-					vartype_name(tv_idx->v_type));
 			    status = FAIL;
 			}
 			else
@@ -2219,6 +2231,58 @@ call_def_function(
 		}
 		break;
 
+	    // unlet range of items in list variable
+	    case ISN_UNLETRANGE:
+		{
+		    // Stack contains:
+		    // -3 index1
+		    // -2 index2
+		    // -1 dict or list
+		    typval_T	*tv_idx1 = STACK_TV_BOT(-3);
+		    typval_T	*tv_idx2 = STACK_TV_BOT(-2);
+		    typval_T	*tv_dest = STACK_TV_BOT(-1);
+		    int		status = OK;
+
+		    if (tv_dest->v_type == VAR_LIST)
+		    {
+			// indexes must be a number
+			SOURCING_LNUM = iptr->isn_lnum;
+			if (check_for_number(tv_idx1) == FAIL
+				|| check_for_number(tv_idx2) == FAIL)
+			{
+			    status = FAIL;
+			}
+			else
+			{
+			    list_T	*l = tv_dest->vval.v_list;
+			    long	n1 = (long)tv_idx1->vval.v_number;
+			    long	n2 = (long)tv_idx2->vval.v_number;
+			    listitem_T	*li;
+
+			    li = list_find_index(l, &n1);
+			    if (li == NULL
+				     || list_unlet_range(l, li, NULL, n1,
+							    TRUE, n2) == FAIL)
+				status = FAIL;
+			}
+		    }
+		    else
+		    {
+			status = FAIL;
+			SOURCING_LNUM = iptr->isn_lnum;
+			semsg(_(e_cannot_index_str),
+						vartype_name(tv_dest->v_type));
+		    }
+
+		    clear_tv(tv_idx1);
+		    clear_tv(tv_idx2);
+		    clear_tv(tv_dest);
+		    ectx.ec_stack.ga_len -= 3;
+		    if (status == FAIL)
+			goto on_error;
+		}
+		break;
+
 	    // push constant
 	    case ISN_PUSHNR:
 	    case ISN_PUSHBOOL:
@@ -4151,6 +4215,9 @@ ex_disassemble(exarg_T *eap)
 	    case ISN_UNLETINDEX:
 		smsg("%4d UNLETINDEX", current);
 		break;
+	    case ISN_UNLETRANGE:
+		smsg("%4d UNLETRANGE", current);
+		break;
 	    case ISN_LOCKCONST:
 		smsg("%4d LOCKCONST", current);
 		break;