patch 8.2.3332: Vim9: cannot assign to range in list

Problem:    Vim9: cannot assign to range in list.
Solution:   Implement overwriting a list range.

Author: brammool

src/eval.c

@@ -45,7 +45,6 @@ typedef struct
     int		fi_byte_idx;	// byte index in fi_string
 } forinfo_T;
 
-static int tv_op(typval_T *tv1, typval_T *tv2, char_u  *op);
 static int eval2(char_u **arg, typval_T *rettv, evalarg_T *evalarg);
 static int eval3(char_u **arg, typval_T *rettv, evalarg_T *evalarg);
 static int eval4(char_u **arg, typval_T *rettv, evalarg_T *evalarg);
@@ -827,7 +826,6 @@ get_lval(
     typval_T	var1;
     typval_T	var2;
     int		empty1 = FALSE;
-    listitem_T	*ni;
     char_u	*key = NULL;
     int		len;
     hashtab_T	*ht = NULL;
@@ -1210,23 +1208,11 @@ get_lval(
 
 	    lp->ll_dict = NULL;
 	    lp->ll_list = lp->ll_tv->vval.v_list;
-	    lp->ll_li = list_find_index(lp->ll_list, &lp->ll_n1);
+	    lp->ll_li = check_range_index_one(lp->ll_list, &lp->ll_n1, quiet);
 	    if (lp->ll_li == NULL)
 	    {
-		// Vim9: Allow for adding an item at the end.
-		if (in_vim9script() && lp->ll_n1 == lp->ll_list->lv_len
-						  && lp->ll_list->lv_lock == 0)
-		{
-		    list_append_number(lp->ll_list, 0);
-		    lp->ll_li = list_find_index(lp->ll_list, &lp->ll_n1);
-		}
-		if (lp->ll_li == NULL)
-		{
-		    clear_tv(&var2);
-		    if (!quiet)
-			semsg(_(e_listidx), lp->ll_n1);
-		    return NULL;
-		}
+		clear_tv(&var2);
+		return NULL;
 	    }
 
 	    if (lp->ll_valtype != NULL)
@@ -1244,27 +1230,10 @@ get_lval(
 		lp->ll_n2 = (long)tv_get_number(&var2);
 						    // is number or string
 		clear_tv(&var2);
-		if (lp->ll_n2 < 0)
-		{
-		    ni = list_find(lp->ll_list, lp->ll_n2);
-		    if (ni == NULL)
-		    {
-			if (!quiet)
-			    semsg(_(e_listidx), lp->ll_n2);
-			return NULL;
-		    }
-		    lp->ll_n2 = list_idx_of_item(lp->ll_list, ni);
-		}
-
-		// Check that lp->ll_n2 isn't before lp->ll_n1.
-		if (lp->ll_n1 < 0)
-		    lp->ll_n1 = list_idx_of_item(lp->ll_list, lp->ll_li);
-		if (lp->ll_n2 < lp->ll_n1)
-		{
-		    if (!quiet)
-			semsg(_(e_listidx), lp->ll_n2);
+		if (check_range_index_two(lp->ll_list,
+					    &lp->ll_n1, lp->ll_li,
+					    &lp->ll_n2, quiet) == FAIL)
 		    return NULL;
-		}
 	    }
 
 	    lp->ll_tv = &lp->ll_li->li_tv;
@@ -1303,7 +1272,6 @@ set_var_lval(
     int		var_idx)    // index for "let [a, b] = list"
 {
     int		cc;
-    listitem_T	*ri;
     dictitem_T	*di;
 
     if (lp->ll_tv == NULL)
@@ -1383,63 +1351,15 @@ set_var_lval(
 	;
     else if (lp->ll_range)
     {
-	listitem_T *ll_li = lp->ll_li;
-	int	    ll_n1 = lp->ll_n1;
-
 	if ((flags & (ASSIGN_CONST | ASSIGN_FINAL))
 					     && (flags & ASSIGN_FOR_LOOP) == 0)
 	{
 	    emsg(_("E996: Cannot lock a range"));
 	    return;
 	}
 
-	/*
-	 * Check whether any of the list items is locked
-	 */
-	for (ri = rettv->vval.v_list->lv_first; ri != NULL && ll_li != NULL; )
-	{
-	    if (value_check_lock(ll_li->li_tv.v_lock, lp->ll_name, FALSE))
-		return;
-	    ri = ri->li_next;
-	    if (ri == NULL || (!lp->ll_empty2 && lp->ll_n2 == ll_n1))
-		break;
-	    ll_li = ll_li->li_next;
-	    ++ll_n1;
-	}
-
-	/*
-	 * Assign the List values to the list items.
-	 */
-	for (ri = rettv->vval.v_list->lv_first; ri != NULL; )
-	{
-	    if (op != NULL && *op != '=')
-		tv_op(&lp->ll_li->li_tv, &ri->li_tv, op);
-	    else
-	    {
-		clear_tv(&lp->ll_li->li_tv);
-		copy_tv(&ri->li_tv, &lp->ll_li->li_tv);
-	    }
-	    ri = ri->li_next;
-	    if (ri == NULL || (!lp->ll_empty2 && lp->ll_n2 == lp->ll_n1))
-		break;
-	    if (lp->ll_li->li_next == NULL)
-	    {
-		// Need to add an empty item.
-		if (list_append_number(lp->ll_list, 0) == FAIL)
-		{
-		    ri = NULL;
-		    break;
-		}
-	    }
-	    lp->ll_li = lp->ll_li->li_next;
-	    ++lp->ll_n1;
-	}
-	if (ri != NULL)
-	    emsg(_(e_list_value_has_more_items_than_targets));
-	else if (lp->ll_empty2
-		? (lp->ll_li != NULL && lp->ll_li->li_next != NULL)
-		: lp->ll_n1 != lp->ll_n2)
-	    emsg(_(e_list_value_does_not_have_enough_items));
+	(void)list_assign_range(lp->ll_list, rettv->vval.v_list,
+			 lp->ll_n1, lp->ll_n2, lp->ll_empty2, op, lp->ll_name);
     }
     else
     {
@@ -1507,7 +1427,7 @@ set_var_lval(
  * and "tv1 .= tv2"
  * Returns OK or FAIL.
  */
-    static int
+    int
 tv_op(typval_T *tv1, typval_T *tv2, char_u *op)
 {
     varnumber_T	n;

src/list.c

@@ -761,6 +761,158 @@ list_insert(list_T *l, listitem_T *ni, listitem_T *item)
     }
 }
 
+/*
+ * Get the list item in "l" with index "n1".  "n1" is adjusted if needed.
+ * In Vim9, it is at the end of the list, add an item.
+ * Return NULL if there is no such item.
+ */
+    listitem_T *
+check_range_index_one(list_T *l, long *n1, int quiet)
+{
+    listitem_T *li = list_find_index(l, n1);
+
+    if (li == NULL)
+    {
+	// Vim9: Allow for adding an item at the end.
+	if (in_vim9script() && *n1 == l->lv_len && l->lv_lock == 0)
+	{
+	    list_append_number(l, 0);
+	    li = list_find_index(l, n1);
+	}
+	if (li == NULL)
+	{
+	    if (!quiet)
+		semsg(_(e_listidx), *n1);
+	    return NULL;
+	}
+    }
+    return li;
+}
+
+/*
+ * Check that "n2" can be used as the second index in a range of list "l".
+ * If "n1" or "n2" is negative it is changed to the positive index.
+ * "li1" is the item for item "n1".
+ * Return OK or FAIL.
+ */
+    int
+check_range_index_two(
+	list_T	    *l,
+	long	    *n1,
+	listitem_T  *li1,
+	long	    *n2,
+	int	    quiet)
+{
+    if (*n2 < 0)
+    {
+	listitem_T	*ni = list_find(l, *n2);
+
+	if (ni == NULL)
+	{
+	    if (!quiet)
+		semsg(_(e_listidx), *n2);
+	    return FAIL;
+	}
+	*n2 = list_idx_of_item(l, ni);
+    }
+
+    // Check that n2 isn't before n1.
+    if (*n1 < 0)
+	*n1 = list_idx_of_item(l, li1);
+    if (*n2 < *n1)
+    {
+	if (!quiet)
+	    semsg(_(e_listidx), *n2);
+	return FAIL;
+    }
+    return OK;
+}
+
+/*
+ * Assign values from list "src" into a range of "dest".
+ * "idx1_arg" is the index of the first item in "dest" to be replaced.
+ * "idx2" is the index of last item to be replaced, but when "empty_idx2" is
+ * TRUE then replace all items after "idx1".
+ * "op" is the operator, normally "=" but can be "+=" and the like.
+ * "varname" is used for error messages.
+ * Returns OK or FAIL.
+ */
+    int
+list_assign_range(
+	list_T	    *dest,
+	list_T	    *src,
+	long	    idx1_arg,
+	long	    idx2,
+	int	    empty_idx2,
+	char_u	    *op,
+	char_u	    *varname)
+{
+    listitem_T	*src_li;
+    listitem_T	*dest_li;
+    long	idx1 = idx1_arg;
+    listitem_T	*first_li = list_find_index(dest, &idx1);
+    long	idx;
+
+    /*
+     * Check whether any of the list items is locked before making any changes.
+     */
+    idx = idx1;
+    dest_li = first_li;
+    for (src_li = src->lv_first; src_li != NULL && dest_li != NULL; )
+    {
+	if (value_check_lock(dest_li->li_tv.v_lock, varname, FALSE))
+	    return FAIL;
+	src_li = src_li->li_next;
+	if (src_li == NULL || (!empty_idx2 && idx2 == idx))
+	    break;
+	dest_li = dest_li->li_next;
+	++idx;
+    }
+
+    /*
+     * Assign the List values to the list items.
+     */
+    idx = idx1;
+    dest_li = first_li;
+    for (src_li = src->lv_first; src_li != NULL; )
+    {
+	if (op != NULL && *op != '=')
+	    tv_op(&dest_li->li_tv, &src_li->li_tv, op);
+	else
+	{
+	    clear_tv(&dest_li->li_tv);
+	    copy_tv(&src_li->li_tv, &dest_li->li_tv);
+	}
+	src_li = src_li->li_next;
+	if (src_li == NULL || (!empty_idx2 && idx2 == idx))
+	    break;
+	if (dest_li->li_next == NULL)
+	{
+	    // Need to add an empty item.
+	    if (list_append_number(dest, 0) == FAIL)
+	    {
+		src_li = NULL;
+		break;
+	    }
+	}
+	dest_li = dest_li->li_next;
+	++idx;
+    }
+    if (src_li != NULL)
+    {
+	emsg(_(e_list_value_has_more_items_than_targets));
+	return FAIL;
+    }
+    if (empty_idx2
+	    ? (dest_li != NULL && dest_li->li_next != NULL)
+	    : idx != idx2)
+    {
+	emsg(_(e_list_value_does_not_have_enough_items));
+	return FAIL;
+    }
+    return OK;
+}
+
 /*
  * Flatten "list" to depth "maxdepth".
  * It does nothing if "maxdepth" is 0.

src/proto/eval.pro

@@ -26,6 +26,7 @@ int eval_foldexpr(char_u *arg, int *cp);
 char_u *get_lval(char_u *name, typval_T *rettv, lval_T *lp, int unlet, int skip, int flags, int fne_flags);
 void clear_lval(lval_T *lp);
 void set_var_lval(lval_T *lp, char_u *endp, typval_T *rettv, int copy, int flags, char_u *op, int var_idx);
+int tv_op(typval_T *tv1, typval_T *tv2, char_u *op);
 void *eval_for_line(char_u *arg, int *errp, exarg_T *eap, evalarg_T *evalarg);
 void skip_for_lines(void *fi_void, evalarg_T *evalarg);
 int next_for_item(void *fi_void, char_u *arg);

src/proto/list.pro

@@ -30,6 +30,9 @@ int list_append_string(list_T *l, char_u *str, int len);
 int list_append_number(list_T *l, varnumber_T n);
 int list_insert_tv(list_T *l, typval_T *tv, listitem_T *item);
 void list_insert(list_T *l, listitem_T *ni, listitem_T *item);
+listitem_T *check_range_index_one(list_T *l, long *n1, int quiet);
+int check_range_index_two(list_T *l, long *n1, listitem_T *li1, long *n2, int quiet);
+int list_assign_range(list_T *dest, list_T *src, long idx1_arg, long idx2, int empty_idx2, char_u *op, char_u *varname);
 void f_flatten(typval_T *argvars, typval_T *rettv);
 void f_flattennew(typval_T *argvars, typval_T *rettv);
 int list_extend(list_T *l1, list_T *l2, listitem_T *bef);

src/testdir/test_listdict.vim

@@ -164,11 +164,14 @@ endfunc
 
 " test for range assign
 func Test_list_range_assign()
-  let l = [0]
-  let l[:] = [1, 2]
-  call assert_equal([1, 2], l)
-  let l[-4:-1] = [5, 6]
-  call assert_equal([5, 6], l)
+  let lines =<< trim END
+      VAR l = [0]
+      LET l[:] = [1, 2]
+      call assert_equal([1, 2], l)
+      LET l[-4 : -1] = [5, 6]
+      call assert_equal([5, 6], l)
+  END
+  call CheckLegacyAndVim9Success(lines)
 endfunc
 
 " Test removing items in list

src/testdir/test_vim9_assign.vim

@@ -1821,7 +1821,7 @@ def Test_unlet()
   CheckDefFailure([
     'var ll = [1, 2]',
     'll[1 : 2] = 7',
-    ], 'E1165:', 2)
+    ], 'E1012: Type mismatch; expected list<number> but got number', 2)
   CheckDefFailure([
     'var dd = {a: 1}',
     'unlet dd["a" : "a"]',

src/version.c

@@ -755,6 +755,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3332,
 /**/
     3331,
 /**/