Merge pull request #71369 from oscbyspro/main

BinaryInteger advanced(by:) fixes

Author: glessard

stdlib/public/core/Integers.swift

@@ -1624,17 +1624,15 @@ extension BinaryInteger {
   @inlinable
   @inline(__always)
   public func advanced(by n: Int) -> Self {
-    if !Self.isSigned {
+    if Self.isSigned {
+      return self.bitWidth < n.bitWidth
+        ? Self(Int(truncatingIfNeeded: self) + n)
+        : self + Self(truncatingIfNeeded: n)
+    } else {
       return n < (0 as Int)
-        ? self - Self(-n)
-        : self + Self(n)
-    }
-    if (self < (0 as Self)) == (n < (0 as Self)) {
-      return self + Self(n)
+        ? self - Self(UInt(bitPattern: ~n &+ 1))
+        : self + Self(UInt(bitPattern: n))
     }
-    return self.magnitude < n.magnitude
-      ? Self(Int(self) + n)
-      : self + Self(n)
   }
 }
 

test/stdlib/Integers.swift.gyb

@@ -852,6 +852,9 @@ tests.test("Strideable") {
   expectEqual(dist(UInt8.max, UInt8.min), -255)
   expectEqual(dist(Int8.min, Int8.max), 255)
   expectEqual(dist(Int8.max, Int8.min), -255)
+  
+  expectEqual(Int8.min.advanced(by: Int(Int8.max)+1), 0)
+  expectEqual(UInt.max.advanced(by: Int.min), UInt.max / 2)
 }
 
 tests.test("signum/generic") {