From 86b8a0890c6179afd6300c47851c7ac0f8101ccf Mon Sep 17 00:00:00 2001
From: Mathias Quintero <me@quintero.io>
Date: Mon, 8 Feb 2021 00:40:42 +0100
Subject: [PATCH] Fixing negative remainder offset

---
 Sources/Syntax/Implementations/Structure/TupleParser.swift | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Sources/Syntax/Implementations/Structure/TupleParser.swift b/Sources/Syntax/Implementations/Structure/TupleParser.swift
index a43b4ae..b3a4251 100644
--- a/Sources/Syntax/Implementations/Structure/TupleParser.swift
+++ b/Sources/Syntax/Implementations/Structure/TupleParser.swift
@@ -72,7 +72,11 @@ private protocol ValuePopper { }
 extension ValuePopper {
 
     static func pop<T : Collection>(from scanner: Scanner, into pointer: UnsafeMutableRawPointer, followedBy next: T) throws where T.Element == Any.Type {
-        let byteOffsetNeeded = (MemoryLayout<Self>.alignment - Int(UInt(bitPattern: pointer))) % MemoryLayout<Self>.alignment
+        var byteOffsetNeeded = (MemoryLayout<Self>.alignment - Int(UInt(bitPattern: pointer))) % MemoryLayout<Self>.alignment
+        if byteOffsetNeeded < 0 {
+            byteOffsetNeeded += MemoryLayout<Self>.alignment
+        }
+
         let pointer = pointer.advanced(by: byteOffsetNeeded)
 
         if let nextType = next.first {