Add Analyzer for banning `init;` props

turns out you can write to `readonly` fields from these, which is a
convention I'm not willing to break

.global.editorconfig.ini

@@ -19,6 +19,8 @@ dotnet_diagnostic.BHI1005.severity = silent
 dotnet_diagnostic.BHI1006.severity = error
 # Don't use target-typed new for throw expressions
 dotnet_diagnostic.BHI1007.severity = error
+# Do not use init setter
+dotnet_diagnostic.BHI1008.severity = error
 # Don't call this.GetType() in sealed type, use typeof operator
 dotnet_diagnostic.BHI1100.severity = error
 # Don't call this.GetType(), use typeof operator (or replace subtype check with better encapsulation)

ExternalProjects/BizHawk.Analyzer/HawkSourceAnalyzer.cs

@@ -55,6 +55,14 @@ public class HawkSourceAnalyzer : DiagnosticAnalyzer
 		defaultSeverity: DiagnosticSeverity.Error,
 		isEnabledByDefault: true);
 
+	private static readonly DiagnosticDescriptor DiagNoInitAccessor = new(
+		id: "BHI1008",
+		title: "Do not use init setter",
+		messageFormat: "Use a regular `set`ter (or add a constructor parameter)",
+		category: "Usage",
+		defaultSeverity: DiagnosticSeverity.Error,
+		isEnabledByDefault: false);
+
 	private static readonly DiagnosticDescriptor DiagNoQueryExpression = new(
 		id: "BHI1003",
 		title: "Do not use query expression syntax",
@@ -119,6 +127,7 @@ public class HawkSourceAnalyzer : DiagnosticAnalyzer
 		DiagNoAnonClasses,
 		DiagNoAnonDelegates,
 		DiagNoDiscardingLocals,
+		DiagNoInitAccessor,
 		DiagNoQueryExpression,
 		DiagRecordImplicitlyRefType,
 		DiagSwitchShouldThrowIOE,
@@ -170,6 +179,9 @@ public class HawkSourceAnalyzer : DiagnosticAnalyzer
 					}
 					switch (snac.Node)
 					{
+						case AccessorDeclarationSyntax ads:
+							if (ads.Keyword.ToString() is "init") DiagNoInitAccessor.ReportAt(ads, snac);
+							break;
 						case AnonymousMethodExpressionSyntax:
 							DiagNoAnonDelegates.ReportAt(snac.Node, snac);
 							break;
@@ -218,6 +230,7 @@ public class HawkSourceAnalyzer : DiagnosticAnalyzer
 				SyntaxKind.AnonymousObjectCreationExpression,
 				SyntaxKind.AnonymousMethodExpression,
 				SyntaxKind.CollectionExpression,
+				SyntaxKind.InitAccessorDeclaration,
 				SyntaxKind.InterpolatedStringExpression,
 				SyntaxKind.ListPattern,
 				SyntaxKind.QueryExpression,

ExternalProjects/BizHawk.AnalyzersTests/BizHawk.Analyzer/HawkSourceAnalyzerTests.cs

@@ -101,6 +101,17 @@ public sealed class HawkSourceAnalyzerTests
 			}
 		""");
 
+	[TestMethod]
+	public Task CheckMisuseOfInitAccessor()
+		=> Verify.VerifyAnalyzerAsync("""
+			public sealed class Cases {
+				public int A { get; {|BHI1008:init;|} }
+			}
+			namespace System.Runtime.CompilerServices {
+				public static class IsExternalInit {} // this sample is compiled for lowest-common-denominator of `netstandard2.0`, so `init` accessor gives an error without this
+			}
+		""");
+
 	[TestMethod]
 	public Task CheckMisuseOfInterpolatedString()
 		=> Verify.VerifyAnalyzerAsync("""

src/BizHawk.Client.Common/FilesystemFilterSet.cs

@@ -9,9 +9,9 @@ namespace BizHawk.Client.Common
 	{
 		private string? _ser = null;
 
-		public bool AppendAllFilesEntry { get; init; } = true;
+		public bool AppendAllFilesEntry { get; set; } = true;
 
-		public string? CombinedEntryDesc { get; init; } = null;
+		public string? CombinedEntryDesc { get; set; } = null;
 
 		private IReadOnlyCollection<string> CombinedExts
 			=> Filters.SelectMany(static filter => filter.Extensions).Distinct().Order().ToList();

src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.Memory.cs

@@ -107,9 +107,11 @@ namespace BizHawk.Client.EmuHawk
 			private readonly uint _domainAddrStart; // addr of _domain where bank begins
 			private readonly uint _addressMangler; // of course, let's *not* correct internal core byteswapping!
 
-			public ReadMemoryFunc ReadFunc { get; protected init; }
+			public virtual ReadMemoryFunc ReadFunc { get; }
-			public WriteMemoryFunc WriteFunc { get; protected init; }
+
-			public ReadMemoryBlockFunc ReadBlockFunc { get; protected init; }
+			public virtual WriteMemoryFunc WriteFunc { get; }
+
+			public virtual ReadMemoryBlockFunc ReadBlockFunc { get; }
 
 			public uint StartAddress; // this is set for our rcheevos impl
 			public readonly uint BankSize;
@@ -192,13 +194,17 @@ namespace BizHawk.Client.EmuHawk
 
 		private class NullMemFunctions : MemFunctions
 		{
+			public override ReadMemoryFunc ReadFunc
+				=> null;
+
+			public override WriteMemoryFunc WriteFunc
+				=> null;
+
+			public override ReadMemoryBlockFunc ReadBlockFunc
+				=> null;
+
 			public NullMemFunctions(long bankSize)
-				: base(null, 0, bankSize)
+				: base(null, 0, bankSize) {}
-			{
-				ReadFunc = null;
-				WriteFunc = null;
-				ReadBlockFunc = null;
-			}
 		}
 
 		// this is a complete hack because the libretro Intelli core sucks and so achievements are made expecting this format

src/BizHawk.Client.EmuHawk/config/SNES/BSNESOptions.cs

@@ -97,31 +97,31 @@ namespace BizHawk.Client.EmuHawk
 		private bool AlwaysDoubleSize
 		{
 			get => cbDoubleSize.Checked;
-			init => cbDoubleSize.Checked = value;
+			set => cbDoubleSize.Checked = value;
 		}
 
 		private bool CropSGBFrame
 		{
 			get => cbCropSGBFrame.Checked;
-			init => cbCropSGBFrame.Checked = value;
+			set => cbCropSGBFrame.Checked = value;
 		}
 
 		private bool NoPPUSpriteLimit
 		{
 			get => cbNoPPUSpriteLimit.Checked;
-			init => cbNoPPUSpriteLimit.Checked = value;
+			set => cbNoPPUSpriteLimit.Checked = value;
 		}
 
 		private bool ShowOverscan
 		{
 			get => cbShowOverscan.Checked;
-			init => cbShowOverscan.Checked = value;
+			set => cbShowOverscan.Checked = value;
 		}
 
 		private bool ShowCursor
 		{
 			get => cbShowCursor.Checked;
-			init => cbShowCursor.Checked = value;
+			set => cbShowCursor.Checked = value;
 		}
 
 		private BsnesApi.ASPECT_RATIO_CORRECTION AspectRatioCorrection => (BsnesApi.ASPECT_RATIO_CORRECTION)AspectRatioCorrectionBox.SelectedIndex;
@@ -129,43 +129,43 @@ namespace BizHawk.Client.EmuHawk
 		private bool Hotfixes
 		{
 			get => cbGameHotfixes.Checked;
-			init => cbGameHotfixes.Checked = value;
+			set => cbGameHotfixes.Checked = value;
 		}
 
 		private bool FastPPU
 		{
 			get => cbFastPPU.Checked;
-			init => cbDoubleSize.Enabled = cbNoPPUSpriteLimit.Enabled = cbFastPPU.Checked = value;
+			set => cbDoubleSize.Enabled = cbNoPPUSpriteLimit.Enabled = cbFastPPU.Checked = value;
 		}
 
 		private bool FastDSP
 		{
 			get => cbFastDSP.Checked;
-			init => cbFastDSP.Checked = value;
+			set => cbFastDSP.Checked = value;
 		}
 
 		private bool FastCoprocessors
 		{
 			get => cbFastCoprocessor.Checked;
-			init => cbFastCoprocessor.Checked = value;
+			set => cbFastCoprocessor.Checked = value;
 		}
 
 		private bool UseSGB2
 		{
 			get => cbUseSGB2.Checked;
-			init => cbUseSGB2.Checked = value;
+			set => cbUseSGB2.Checked = value;
 		}
 
 		private bool UseRealTime
 		{
 			get => cbUseRealTime.Checked;
-			init => cbUseRealTime.Checked = value;
+			set => cbUseRealTime.Checked = value;
 		}
 
 		private DateTime InitialTime
 		{
 			get => dtpInitialTime.Value;
-			init => dtpInitialTime.Value = value;
+			set => dtpInitialTime.Value = value;
 		}
 
 		private BsnesApi.ENTROPY Entropy => (BsnesApi.ENTROPY) EntropyBox.SelectedIndex;
@@ -174,19 +174,77 @@ namespace BizHawk.Client.EmuHawk
 
 		private BsnesCore.SATELLAVIEW_CARTRIDGE SatellaviewCartridge => (BsnesCore.SATELLAVIEW_CARTRIDGE)SatellaviewCartridgeBox.SelectedIndex;
 
-		private bool ShowObj1 { get => Obj1Checkbox.Checked; init => Obj1Checkbox.Checked = value; }
+		private bool ShowObj1
-		private bool ShowObj2 { get => Obj2Checkbox.Checked; init => Obj2Checkbox.Checked = value; }
+		{
-		private bool ShowObj3 { get => Obj3Checkbox.Checked; init => Obj3Checkbox.Checked = value; }
+			get => Obj1Checkbox.Checked;
-		private bool ShowObj4 { get => Obj4Checkbox.Checked; init => Obj4Checkbox.Checked = value; }
+			set => Obj1Checkbox.Checked = value;
+		}
 
-		private bool ShowBg1_0 { get => Bg1_0Checkbox.Checked; init => Bg1_0Checkbox.Checked = value; }
+		private bool ShowObj2
-		private bool ShowBg1_1 { get => Bg1_1Checkbox.Checked; init => Bg1_1Checkbox.Checked = value; }
+		{
-		private bool ShowBg2_0 { get => Bg2_0Checkbox.Checked; init => Bg2_0Checkbox.Checked = value; }
+			get => Obj2Checkbox.Checked;
-		private bool ShowBg2_1 { get => Bg2_1Checkbox.Checked; init => Bg2_1Checkbox.Checked = value; }
+			set => Obj2Checkbox.Checked = value;
-		private bool ShowBg3_0 { get => Bg3_0Checkbox.Checked; init => Bg3_0Checkbox.Checked = value; }
+		}
-		private bool ShowBg3_1 { get => Bg3_1Checkbox.Checked; init => Bg3_1Checkbox.Checked = value; }
+
-		private bool ShowBg4_0 { get => Bg4_0Checkbox.Checked; init => Bg4_0Checkbox.Checked = value; }
+		private bool ShowObj3
-		private bool ShowBg4_1 { get => Bg4_1Checkbox.Checked; init => Bg4_1Checkbox.Checked = value; }
+		{
+			get => Obj3Checkbox.Checked;
+			set => Obj3Checkbox.Checked = value;
+		}
+
+		private bool ShowObj4
+		{
+			get => Obj4Checkbox.Checked;
+			set => Obj4Checkbox.Checked = value;
+		}
+
+		private bool ShowBg1_0
+		{
+			get => Bg1_0Checkbox.Checked;
+			set => Bg1_0Checkbox.Checked = value;
+		}
+
+		private bool ShowBg1_1
+		{
+			get => Bg1_1Checkbox.Checked;
+			set => Bg1_1Checkbox.Checked = value;
+		}
+
+		private bool ShowBg2_0
+		{
+			get => Bg2_0Checkbox.Checked;
+			set => Bg2_0Checkbox.Checked = value;
+		}
+
+		private bool ShowBg2_1
+		{
+			get => Bg2_1Checkbox.Checked;
+			set => Bg2_1Checkbox.Checked = value;
+		}
+
+		private bool ShowBg3_0
+		{
+			get => Bg3_0Checkbox.Checked;
+			set => Bg3_0Checkbox.Checked = value;
+		}
+
+		private bool ShowBg3_1
+		{
+			get => Bg3_1Checkbox.Checked;
+			set => Bg3_1Checkbox.Checked = value;
+		}
+
+		private bool ShowBg4_0
+		{
+			get => Bg4_0Checkbox.Checked;
+			set => Bg4_0Checkbox.Checked = value;
+		}
+
+		private bool ShowBg4_1
+		{
+			get => Bg4_1Checkbox.Checked;
+			set => Bg4_1Checkbox.Checked = value;
+		}
 
 		private void BtnOk_Click(object sender, EventArgs e)
 		{

src/BizHawk.Emulation.Cores/Consoles/Nintendo/BSNES/BsnesControllers.cs

@@ -17,10 +17,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.BSNES
 				BSNES_INPUT_DEVICE.None => new BsnesUnpluggedController(),
 				BSNES_INPUT_DEVICE.Gamepad => new BsnesController(),
 				BSNES_INPUT_DEVICE.ExtendedGamepad => new BsnesExtendedController(),
-				BSNES_INPUT_DEVICE.Mouse => new BsnesMouseController
+				BSNES_INPUT_DEVICE.Mouse => new BsnesMouseController(LimitAnalogChangeSensitivity: ss.LimitAnalogChangeSensitivity),
-				{
-					LimitAnalogChangeSensitivity = ss.LimitAnalogChangeSensitivity
-				},
 				BSNES_INPUT_DEVICE.SuperMultitap => new BsnesMultitapController(),
 				BSNES_INPUT_DEVICE.Payload => new BsnesPayloadController(),
 				BSNES_INPUT_DEVICE.SuperScope => new BsnesSuperScopeController(),
@@ -171,14 +168,13 @@ namespace BizHawk.Emulation.Cores.Nintendo.BSNES
 		}
 	}
 
-	internal class BsnesMouseController : IBsnesController
+	internal class BsnesMouseController(bool LimitAnalogChangeSensitivity = true) : IBsnesController
 	{
 		private static readonly ControllerDefinition _definition = new ControllerDefinition("(SNES Controller fragment)")
 				{ BoolButtons = { "0Mouse Left", "0Mouse Right" } }
 			.AddXYPair("0Mouse {0}", AxisPairOrientation.RightAndDown, (-127).RangeTo(127), 0);
 
 		public ControllerDefinition Definition => _definition;
-		public bool LimitAnalogChangeSensitivity { get; init; } = true;
 
 		public short GetState(IController controller, int index, int id)
 		{

src/BizHawk.Emulation.Cores/Consoles/Nintendo/Gameboy/Gambatte.cs

@@ -642,24 +642,22 @@ namespace BizHawk.Emulation.Cores.Nintendo.Gameboy
 			{
 				throw new InvalidOperationException("Unexpected error in gambatte_getmemoryarea");
 			}
-			return new GPUMemoryAreas
+			return new GPUMemoryAreas(vram: _vram, oam: _oam, sppal: _sppal, bgpal: _bgpal);
-			{
-				Vram = _vram,
-				Oam = _oam,
-				Sppal = _sppal,
-				Bgpal = _bgpal,
-			};
 		}
 
-		private class GPUMemoryAreas : IGPUMemoryAreas
+		private sealed class GPUMemoryAreas(IntPtr vram, IntPtr oam, IntPtr sppal, IntPtr bgpal) : IGPUMemoryAreas
 		{
-			public IntPtr Vram { get; init; }
+			public IntPtr Vram
+				=> vram;
 
-			public IntPtr Oam { get; init; }
+			public IntPtr Oam
+				=> oam;
 
-			public IntPtr Sppal { get; init; }
+			public IntPtr Sppal
+				=> sppal;
 
-			public IntPtr Bgpal { get; init; }
+			public IntPtr Bgpal
+				=> bgpal;
 
 			public void Dispose() {}
 		}

src/BizHawk.Emulation.Cores/Consoles/Nintendo/SNES/SNESGraphicsDecoder.cs

@@ -350,45 +350,45 @@ namespace BizHawk.Emulation.Cores.Nintendo.SNES
 
 			public BGInfos BG = new BGInfos();
 
-			public int Mode { get; init; }
+			public int Mode { get; internal set; }
-			public bool Mode1_BG3_Priority { get; init; }
+			public bool Mode1_BG3_Priority { get; internal set; }
 
-			public bool SETINI_Mode7ExtBG { get; init; }
+			public bool SETINI_Mode7ExtBG { get; internal set; }
-			public bool SETINI_HiRes { get; init; }
+			public bool SETINI_HiRes { get; internal set; }
-			public bool SETINI_Overscan { get; init; }
+			public bool SETINI_Overscan { get; internal set; }
-			public bool SETINI_ObjInterlace { get; init; }
+			public bool SETINI_ObjInterlace { get; internal set; }
-			public bool SETINI_ScreenInterlace { get; init; }
+			public bool SETINI_ScreenInterlace { get; internal set; }
 
-			public int CGWSEL_ColorMask { get; init; }
+			public int CGWSEL_ColorMask { get; internal set; }
-			public int CGWSEL_ColorSubMask { get; init; }
+			public int CGWSEL_ColorSubMask { get; internal set; }
-			public int CGWSEL_AddSubMode { get; init; }
+			public int CGWSEL_AddSubMode { get; internal set; }
-			public bool CGWSEL_DirectColor { get; init; }
+			public bool CGWSEL_DirectColor { get; internal set; }
-			public int CGADSUB_AddSub { get; init; }
+			public int CGADSUB_AddSub { get; internal set; }
-			public bool CGADSUB_Half { get; init; }
+			public bool CGADSUB_Half { get; internal set; }
 
-			public int OBSEL_Size { get; init; }
+			public int OBSEL_Size { get; internal set; }
-			public int OBSEL_NameSel { get; init; }
+			public int OBSEL_NameSel { get; internal set; }
-			public int OBSEL_NameBase { get; init; }
+			public int OBSEL_NameBase { get; internal set; }
 
-			public int OBJTable0Addr { get; init; }
+			public int OBJTable0Addr { get; internal set; }
-			public int OBJTable1Addr { get; init; }
+			public int OBJTable1Addr { get; internal set; }
 
-			public bool OBJ_MainEnabled { get; init; }
+			public bool OBJ_MainEnabled { get; internal set; }
-			public bool OBJ_SubEnabled { get; init; }
+			public bool OBJ_SubEnabled { get; internal set; }
-			public bool OBJ_MathEnabled { get; init; }
+			public bool OBJ_MathEnabled { get; internal set; }
-			public bool BK_MathEnabled { get; init; }
+			public bool BK_MathEnabled { get; internal set; }
 
-			public int M7HOFS { get; init; }
+			public int M7HOFS { get; internal set; }
-			public int M7VOFS { get; init; }
+			public int M7VOFS { get; internal set; }
-			public int M7A { get; init; }
+			public int M7A { get; internal set; }
-			public int M7B { get; init; }
+			public int M7B { get; internal set; }
-			public int M7C { get; init; }
+			public int M7C { get; internal set; }
-			public int M7D { get; init; }
+			public int M7D { get; internal set; }
-			public int M7X { get; init; }
+			public int M7X { get; internal set; }
-			public int M7Y { get; init; }
+			public int M7Y { get; internal set; }
-			public int M7SEL_REPEAT { get; init; }
+			public int M7SEL_REPEAT { get; internal set; }
-			public bool M7SEL_HFLIP { get; init; }
+			public bool M7SEL_HFLIP { get; internal set; }
-			public bool M7SEL_VFLIP { get; init; }
+			public bool M7SEL_VFLIP { get; internal set; }
 		}
 
 		public static readonly int[,] ModeBpps = {

src/BizHawk.Emulation.Cores/Consoles/Nintendo/SameBoy/SameBoy.cs

@@ -270,25 +270,22 @@ namespace BizHawk.Emulation.Cores.Nintendo.Sameboy
 			{
 				throw new InvalidOperationException("Unexpected error in sameboy_getmemoryarea");
 			}
-
+			return new GPUMemoryAreas(vram: _vram, oam: _oam, sppal: _sppal, bgpal: _bgpal);
-			return new GPUMemoryAreas()
-			{
-				Vram = _vram,
-				Oam = _oam,
-				Sppal = _sppal,
-				Bgpal = _bgpal
-			};
 		}
 
-		private class GPUMemoryAreas : IGPUMemoryAreas
+		private sealed class GPUMemoryAreas(IntPtr vram, IntPtr oam, IntPtr sppal, IntPtr bgpal) : IGPUMemoryAreas
 		{
-			public IntPtr Vram { get; init; }
+			public IntPtr Vram
+				=> vram;
 
-			public IntPtr Oam { get; init; }
+			public IntPtr Oam
+				=> oam;
 
-			public IntPtr Sppal { get; init; }
+			public IntPtr Sppal
+				=> sppal;
 
-			public IntPtr Bgpal { get; init; }
+			public IntPtr Bgpal
+				=> bgpal;
 
 			public void Dispose() {}
 		}