Allow array_diff() and array_intersect() with single array argument

Both of these functions are well-defined when used with a single
array argument -- rejecting this case was an artificial limitation.
This is not useful when called with explicit arguments, but removes
edge-cases when used with argument unpacking:

    // OK even if $excludes is empty.
    array_diff($array, ...$excludes);

    // OK even if $arrays contains a single array only.
    array_intersect(...$arrays);

This matches the behavior of functions like array_merge() and
array_push(), which also allow calls with no array or a single
array respectively.

Closes GH-6097.

1 files changed, 8 insertions, 0 deletions

diff --git a/UPGRADING b/UPGRADING
index 3d37c2db25..f98ae50d1b 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -771,6 +771,14 @@ PHP 8.0 UPGRADE NOTES
   . Sorting functions are now stable, which means that equal-comparing elements
     will retain their original order.
     RFC: https://wiki.php.net/rfc/stable_sorting
+  . array_diff(), array_intersect() and their variations can now be used with
+    a single array as argument. This means that usages like the following are
+    now possible:
+
+        // OK even if $excludes is empty.
+        array_diff($array, ...$excludes);
+        // OK even if $arrays only contains a single array.
+        array_intersect(...$arrays);
 
 - Zip:
   . Extension updated to version 1.19.0