Merge pull request #28462 from dtorres/patch-1

[LazyFilterSequence] Preserve order of predicates

Author: CodaFi

stdlib/public/core/Filter.swift

@@ -339,7 +339,7 @@ extension LazyFilterSequence {
     _ isIncluded: @escaping (Element) -> Bool
   ) -> LazyFilterSequence<Base> {
     return LazyFilterSequence(_base: _base) {
-      isIncluded($0) && self._predicate($0)
+      self._predicate($0) && isIncluded($0)
     }
   }
 }

test/stdlib/Filter.swift

@@ -73,4 +73,26 @@ FilterTests.test("single-count") {
   expectEqual(30, count)
 }
 
+FilterTests.test("chained filter order") {
+  let array = [1]
+  
+  let lazyFilter = array.lazy
+    .filter { _ in false }
+    .filter { _ in
+      expectUnreachable("Executed second filter before first")
+      return true
+    }
+  let lazyResult = Array(lazyFilter)
+  
+  let result = array
+    .filter { _ in false }
+    .filter { _ in
+      expectUnreachable("Executed second filter before first")
+      return true
+    }
+  
+  expectEqual(lazyResult.count, 0)
+  expectEqual(result.count, 0)
+}
+
 runAllTests()