From 6a201073b14af1166c90ce8f5e9c463ec66fe917 Mon Sep 17 00:00:00 2001
From: Justin Van Patten <jvp@justinvp.com>
Date: Thu, 8 Dec 2016 16:39:28 -0800
Subject: [PATCH] Make TimeZoneInfo.AdjustmentRule fields readonly
 (dotnet/coreclr#8528)

AdjustmentRule is immutable. Help enforce this by making its fields
readonly.

Commit migrated from https://github.com/dotnet/coreclr/commit/d8cd756f2dd5027f2df69ad62cca3c6aec6340ad
---
 .../src/mscorlib/src/System/TimeZoneInfo.cs   | 80 ++++++++++---------
 1 file changed, 43 insertions(+), 37 deletions(-)

diff --git a/src/coreclr/src/mscorlib/src/System/TimeZoneInfo.cs b/src/coreclr/src/mscorlib/src/System/TimeZoneInfo.cs
index 2552d07bb0889..7acffb5e0e86f 100644
--- a/src/coreclr/src/mscorlib/src/System/TimeZoneInfo.cs
+++ b/src/coreclr/src/mscorlib/src/System/TimeZoneInfo.cs
@@ -4475,13 +4475,13 @@ sealed public class AdjustmentRule : IEquatable<AdjustmentRule>, ISerializable,
             {
 
             // ---- SECTION:  members supporting exposed properties -------------*
-            private DateTime m_dateStart;
-            private DateTime m_dateEnd;
-            private TimeSpan m_daylightDelta;
-            private TransitionTime m_daylightTransitionStart;
-            private TransitionTime m_daylightTransitionEnd;
-            private TimeSpan m_baseUtcOffsetDelta;   // delta from the default Utc offset (utcOffset = defaultUtcOffset + m_baseUtcOffsetDelta)
-            private bool m_noDaylightTransitions;
+            private readonly DateTime m_dateStart;
+            private readonly DateTime m_dateEnd;
+            private readonly TimeSpan m_daylightDelta;
+            private readonly TransitionTime m_daylightTransitionStart;
+            private readonly TransitionTime m_daylightTransitionEnd;
+            private readonly TimeSpan m_baseUtcOffsetDelta;   // delta from the default Utc offset (utcOffset = defaultUtcOffset + m_baseUtcOffsetDelta)
+            private readonly bool m_noDaylightTransitions;
 
             // ---- SECTION: public properties --------------*
             public DateTime  DateStart {
@@ -4566,33 +4566,29 @@ sealed public class AdjustmentRule : IEquatable<AdjustmentRule>, ISerializable,
 
             // -------- SECTION: constructors -----------------*
 
-            private AdjustmentRule() { }
-
-
-            // -------- SECTION: factory methods -----------------*
-
-            static internal AdjustmentRule CreateAdjustmentRule(
-                             DateTime dateStart,
-                             DateTime dateEnd,
-                             TimeSpan daylightDelta,
-                             TransitionTime daylightTransitionStart,
-                             TransitionTime daylightTransitionEnd,
-                             bool noDaylightTransitions) {
+            private AdjustmentRule(
+                DateTime dateStart,
+                DateTime dateEnd,
+                TimeSpan daylightDelta,
+                TransitionTime daylightTransitionStart,
+                TransitionTime daylightTransitionEnd,
+                TimeSpan baseUtcOffsetDelta,
+                bool noDaylightTransitions)
+            {
                 ValidateAdjustmentRule(dateStart, dateEnd, daylightDelta,
                        daylightTransitionStart, daylightTransitionEnd, noDaylightTransitions);
 
-                AdjustmentRule rule = new AdjustmentRule();
+                m_dateStart = dateStart;
+                m_dateEnd = dateEnd;
+                m_daylightDelta = daylightDelta;
+                m_daylightTransitionStart = daylightTransitionStart;
+                m_daylightTransitionEnd = daylightTransitionEnd;
+                m_baseUtcOffsetDelta = baseUtcOffsetDelta;
+                m_noDaylightTransitions = noDaylightTransitions;
+            }
 
-                rule.m_dateStart = dateStart;
-                rule.m_dateEnd   = dateEnd;
-                rule.m_daylightDelta = daylightDelta;
-                rule.m_daylightTransitionStart = daylightTransitionStart;
-                rule.m_daylightTransitionEnd = daylightTransitionEnd;
-                rule.m_baseUtcOffsetDelta = TimeSpan.Zero;
-                rule.m_noDaylightTransitions = noDaylightTransitions;
 
-                return rule;
-            }
+            // -------- SECTION: factory methods -----------------*
 
             static public AdjustmentRule CreateAdjustmentRule(
                              DateTime dateStart,
@@ -4601,8 +4597,14 @@ sealed public class AdjustmentRule : IEquatable<AdjustmentRule>, ISerializable,
                              TransitionTime daylightTransitionStart,
                              TransitionTime daylightTransitionEnd)
             {
-                return CreateAdjustmentRule(dateStart, dateEnd, daylightDelta,
-                    daylightTransitionStart, daylightTransitionEnd, noDaylightTransitions: false);
+                return new AdjustmentRule(
+                    dateStart,
+                    dateEnd,
+                    daylightDelta,
+                    daylightTransitionStart,
+                    daylightTransitionEnd,
+                    baseUtcOffsetDelta: TimeSpan.Zero,
+                    noDaylightTransitions: false);
             }
 
             static internal AdjustmentRule CreateAdjustmentRule(
@@ -4612,12 +4614,16 @@ sealed public class AdjustmentRule : IEquatable<AdjustmentRule>, ISerializable,
                              TransitionTime daylightTransitionStart,
                              TransitionTime daylightTransitionEnd,
                              TimeSpan baseUtcOffsetDelta,
-                             bool noDaylightTransitions) {
-                AdjustmentRule rule = CreateAdjustmentRule(dateStart, dateEnd, daylightDelta,
-                    daylightTransitionStart, daylightTransitionEnd, noDaylightTransitions);
-
-                rule.m_baseUtcOffsetDelta = baseUtcOffsetDelta;
-                return rule;
+                             bool noDaylightTransitions)
+            {
+                return new AdjustmentRule(
+                    dateStart,
+                    dateEnd,
+                    daylightDelta,
+                    daylightTransitionStart,
+                    daylightTransitionEnd,
+                    baseUtcOffsetDelta,
+                    noDaylightTransitions);
             }
 
             // ----- SECTION: internal utility methods ----------------*