Enable nullability in most of the remaining files in BizHawk.Common

src/BizHawk.Common/BinaryQuickSerializer.cs

@@ -1,6 +1,4 @@
-#nullable disable
-
-using System;
+using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
@@ -17,15 +15,9 @@ namespace BizHawk.Common
 	public static class BinaryQuickSerializer
 	{
 		private static MethodInfo FromExpression(Expression e)
-		{
-			var caller = e as MethodCallExpression;
-			if (caller == null)
-			{
-				throw new ArgumentException("Expression must be a method call");
-			}
-
-			return caller.Method;
-		}
+			=> e is MethodCallExpression caller
+				? caller.Method
+				: throw new ArgumentException("Expression must be a method call");
 
 		private static MethodInfo Method<T>(Expression<Action<T>> f)
 		{
@@ -95,6 +87,13 @@ namespace BizHawk.Common
 			public Type Type;
 			public Reader Read;
 			public Writer Write;
+
+			public SerializationFactory(Type type, Reader read, Writer write)
+			{
+				Type = type;
+				Read = read;
+				Write = write;
+			}
 		}
 
 		private static SerializationFactory CreateFactory(Type t)
@@ -153,12 +152,10 @@ namespace BizHawk.Common
 				il.Emit(OpCodes.Ret);
 			}
 
-			return new SerializationFactory
-			{
-				Type = t,
-				Read = (Reader)rmeth.CreateDelegate(typeof(Reader)),
-				Write = (Writer)wmeth.CreateDelegate(typeof(Writer))
-			};
+			return new SerializationFactory(
+				t,
+				(Reader) rmeth.CreateDelegate(typeof(Reader)),
+				(Writer) wmeth.CreateDelegate(typeof(Writer)));
 		}
 
 		private static readonly IDictionary<Type, SerializationFactory> Serializers =

src/BizHawk.Common/Bit.cs

@@ -1,5 +1,4 @@
-#nullable disable
-
+using System;
 using System.Diagnostics;
 
 namespace BizHawk.Common
@@ -82,9 +81,9 @@ namespace BizHawk.Common
 			return _val.GetHashCode();
 		}
 
-		public override bool Equals(object obj)
+		public override bool Equals(object? obj)
 		{
-			return this == (Bit)obj;  // this is probably wrong
+			return this == (Bit) (obj ?? throw new NullReferenceException()); // this is probably wrong
 		}
 	}
 }

src/BizHawk.Common/BitReverse.cs

@@ -1,25 +1,8 @@
-#nullable disable
-
-namespace BizHawk.Common
+namespace BizHawk.Common
 {
 	public static class BitReverse
 	{
 		static BitReverse()
-		{
-			MakeByte8();
-		}
-
-		public static byte[] Byte8;
-
-		public static uint Reverse32(uint v)
-		{
-			return (uint)((Byte8[v & 0xff] << 24) |
-					(Byte8[(v >> 8) & 0xff] << 16) |
-					(Byte8[(v >> 16) & 0xff] << 8) |
-					Byte8[(v >> 24) & 0xff]);
-		}
-
-		private static void MakeByte8()
 		{
 			int bits = 8;
 			const int n = 1 << 8;
@@ -42,5 +25,14 @@ namespace BizHawk.Common
 				}
 			}
 		}
+
+		public static readonly byte[] Byte8;
+
+		public static uint Reverse32(uint v) => (uint) (
+			(Byte8[v & 0xFF] << 24)
+				| (Byte8[(v >> 8) & 0xFF] << 16)
+				| (Byte8[(v >> 16) & 0xFF] << 8)
+				| Byte8[(v >> 24) & 0xFF]
+		);
 	}
 }

src/BizHawk.Common/CRC32.cs

@@ -1,6 +1,4 @@
-#nullable disable
-
-namespace BizHawk.Common
+namespace BizHawk.Common
 {
 	// we could get a little list of crcs from here and make it clear which crc this class was for, and expose others
 	// http://www.ross.net/crc/download/crc_v3.txt

src/BizHawk.Common/DeepEquality.cs

@@ -1,6 +1,4 @@
-#nullable disable
-
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
@@ -32,7 +30,7 @@ namespace BizHawk.Common
 		/// <summary>
 		/// return all instance fields of a type
 		/// </summary>
-		public static IEnumerable<FieldInfo> GetAllFields(Type t)
+		public static IEnumerable<FieldInfo> GetAllFields(Type? t)
 		{
 			while (t != null)
 			{
@@ -49,17 +47,20 @@ namespace BizHawk.Common
 			}
 		}
 
-		private static readonly MethodInfo ArrayEqualsGeneric = typeof(DeepEquality).GetMethod("ArrayEquals", BindingFlags.NonPublic | BindingFlags.Static);
+		private static readonly MethodInfo ArrayEqualsGeneric
+			= typeof(DeepEquality).GetMethod("ArrayEquals", BindingFlags.NonPublic | BindingFlags.Static)
+				?? throw new NullReferenceException();
 
 		/// <summary>test if two objects <paramref name="o1"/> and <paramref name="o2"/> are equal, field-by-field (with deep inspection of each field)</summary>
 		/// <exception cref="InvalidOperationException"><paramref name="o1"/> is an array with rank > 1 or is a non-zero-indexed array</exception>
-		public static bool DeepEquals(object o1, object o2)
+		public static bool DeepEquals(object? o1, object? o2)
 		{
 			if (o1 == o2)
 			{
 				// reference equal, so nothing else to be done
 				return true;
 			}
+			if (o1 == null || o2 == null) return false; // not equal (above) and one is null
 
 			Type t1 = o1.GetType();
 			Type t2 = o2.GetType();

src/BizHawk.Common/Extensions/BufferExtensions.cs

@@ -1,6 +1,4 @@
-#nullable disable
-
-using System;
+using System;
 using System.IO;
 using System.Text;
 using System.Security.Cryptography;

src/BizHawk.Common/Extensions/NumberExtensions.cs

@@ -1,6 +1,4 @@
-#nullable disable
-
-using System;
+using System;
 using System.Linq;
 
 namespace BizHawk.Common.NumberExtensions

src/BizHawk.Common/Extensions/ReflectionExtensions.cs

@@ -1,6 +1,4 @@
-#nullable disable
-
-using System;
+using System;
 using System.Linq;
 using System.Collections.Generic;
 using System.ComponentModel;
@@ -52,16 +50,8 @@ namespace BizHawk.Common.ReflectionExtensions
 		/// </summary>
 		public static string DisplayName(this Type type)
 		{
-			var displayName = (DisplayNameAttribute)type
-				.GetCustomAttributes(typeof(DisplayNameAttribute), false)
-				.FirstOrDefault();
-
-			if (displayName != null)
-			{
-				return displayName.DisplayName;
-			}
-
-			return type.Name;
+			var attr = type.GetCustomAttributes(typeof(DisplayNameAttribute), false).FirstOrDefault();
+			return attr is DisplayNameAttribute displayName ? displayName.DisplayName : type.Name;
 		}
 
 		/// <summary>
@@ -70,15 +60,11 @@ namespace BizHawk.Common.ReflectionExtensions
 		/// <param name="description">The description attribute value</param>
 		/// <typeparam name="T">The type of the enum</typeparam>
 		/// <returns>An enum value with the given description attribute, if no suitable description is found then a default value of the enum is returned</returns>
-		/// <exception cref="InvalidOperationException"><typeparamref name="T"/> does not inherit <see cref="Enum"/></exception>
 		/// <remarks>implementation from https://stackoverflow.com/a/4367868/7467292</remarks>
 		public static T GetEnumFromDescription<T>(this string description)
+			where T : Enum
 		{
 			var type = typeof(T);
-			if (!type.IsEnum)
-			{
-				throw new InvalidOperationException();
-			}
 
 			foreach (var field in type.GetFields())
 			{
@@ -99,7 +85,8 @@ namespace BizHawk.Common.ReflectionExtensions
 				}
 			}
 
-			return default(T);
+			var def = default(T); // does anyone know why Roslyn thinks this can evaluate to null? --yoshi
+			return def ?? throw new NullReferenceException();
 		}
 
 		/// <summary>

src/BizHawk.Common/Log.cs

@@ -1,6 +1,4 @@
-#nullable disable
-
-using System;
+using System;
 using System.Collections.Generic;
 using System.IO;
 
@@ -60,13 +58,13 @@ namespace BizHawk.Common
 		}
 
 		// ============== Default Logger Action ==============
-		public static Stream HACK_LOG_STREAM;
+		public static Stream? HACK_LOG_STREAM;
 
 		private static readonly bool LogToConsole = false;
 		private static readonly bool LogToFile = false;
 
 		private const string LogFilename = "bizhawk.txt";
-		private static StreamWriter _writer;
+		private static StreamWriter? _writer;
 
 		private static void DefaultLogger(string message)
 		{
@@ -75,13 +73,9 @@ namespace BizHawk.Common
 				Console.WriteLine(message);
 			}
 
-			if (LogToFile && _writer == null)
-			{
-				_writer = new StreamWriter(LogFilename);
-			}
-
 			if (LogToFile)
 			{
+				_writer ??= new StreamWriter(LogFilename);
 				_writer.WriteLine(message);
 				_writer.Flush();
 			}

src/BizHawk.Common/TempFileManager.cs

@@ -1,5 +1,3 @@
-#nullable disable
-
 using System;
 using System.Linq;
 using System.Collections.Generic;
@@ -17,7 +15,7 @@ namespace BizHawk.Common
 	{
 		// TODO - manage paths other than %temp%, make not static, or allow adding multiple paths to static instance
 
-		public static string GetTempFilename(string friendlyName, string dotAndExtension = null, bool delete = true)
+		public static string GetTempFilename(string friendlyName, string? dotAndExtension = null, bool delete = true)
 		{
 			string guidPart = Guid.NewGuid().ToString();
 			var fname = $"biz-{System.Diagnostics.Process.GetCurrentProcess().Id}-{friendlyName}-{guidPart}{dotAndExtension ?? ""}";
@@ -33,7 +31,7 @@ namespace BizHawk.Common
 		public static string RenameTempFilenameForDelete(string path)
 		{
 			string filename = Path.GetFileName(path);
-			string dir = Path.GetDirectoryName(path);
+			var dir = Path.GetDirectoryName(path) ?? throw new NullReferenceException();
 			if (!filename.StartsWith("biz-"))
 			{
 				throw new InvalidOperationException();
@@ -77,37 +75,35 @@ namespace BizHawk.Common
 
 				foreach(var di in dis)
 				{
-					FileInfo[] fis = null;
+					FileInfo[] fis;
 					try
 					{
 						fis = di.GetFiles("bizdelete-*");
 					}
 					catch
 					{
+						continue;
 					}
 
-					if (fis != null)
+					foreach (var fi in fis)
 					{
-						foreach (var fi in fis)
+						try
 						{
-							try
+							if (OSTailoredCode.IsUnixHost)
 							{
-								if (OSTailoredCode.IsUnixHost)
-								{
-									fi.Delete(); // naive deletion, Mono doesn't care
-								}
-								else
-								{
-									Win32Imports.DeleteFileW(fi.FullName); // SHUT. UP. THE. EXCEPTIONS.
-								}
+								fi.Delete(); // naive deletion, Mono doesn't care
 							}
-							catch
+							else
 							{
+								Win32Imports.DeleteFileW(fi.FullName); // SHUT. UP. THE. EXCEPTIONS.
 							}
-
-							// try not to do more than one thing per frame
-							Thread.Sleep(100);
 						}
+						catch
+						{
+						}
+
+						// try not to do more than one thing per frame
+						Thread.Sleep(100);
 					}
 				}
 
@@ -120,7 +116,7 @@ namespace BizHawk.Common
 		{
 		}
 
-		private static Thread thread;
+		private static Thread? thread;
 
 		public static void HelperSetTempPath(string path)
 		{