Enable MA0098 and fix noncompliance

"Use indexer instead of LINQ methods"

Common.ruleset

@@ -402,7 +402,7 @@
 		<Rule Id="MA0097" Action="Hidden" />
 
 		<!-- Use indexer instead of LINQ methods -->
-		<Rule Id="MA0098" Action="Hidden" />
+		<Rule Id="MA0098" Action="Warning" />
 
 		<!-- Use Explicit enum value instead of 0 -->
 		<Rule Id="MA0099" Action="Hidden" />

src/BizHawk.Common/Extensions/PathExtensions.cs

@@ -2,7 +2,6 @@
 using System.Text;
 using System.IO;
 using System.Reflection;
-using System.Linq;
 
 using BizHawk.Common.StringExtensions;
 
@@ -79,18 +78,8 @@ namespace BizHawk.Common.PathExtensions
 			//TODO merge this with the Windows implementation in MakeRelativeTo
 			static FileAttributes GetPathAttribute(string path1)
 			{
-				var di = new DirectoryInfo(path1.Split('|').First());
+				if (Directory.Exists(path1.SubstringBefore('|'))) return FileAttributes.Directory;
-				if (di.Exists)
+				if (File.Exists(path1.SubstringBefore('|'))) return FileAttributes.Normal;
-				{
-					return FileAttributes.Directory;
-				}
-
-				var fi = new FileInfo(path1.Split('|').First());
-				if (fi.Exists)
-				{
-					return FileAttributes.Normal;
-				}
-
 				throw new FileNotFoundException();
 			}
 			var path = new StringBuilder(260 /* = MAX_PATH */);

src/BizHawk.Common/Extensions/StringExtensions.cs

@@ -82,6 +82,23 @@ namespace BizHawk.Common.StringExtensions
 			return index < 0 ? notFoundValue : str.Substring(index + delimiter.Length, str.Length - index - delimiter.Length);
 		}
 
+		/// <returns>
+		/// the substring of <paramref name="str"/> after the last occurrence of <paramref name="delimiter"/>, or
+		/// the original <paramref name="str"/> if not found
+		/// </returns>
+		public static string SubstringAfterLast(this string str, char delimiter)
+			=> str.SubstringAfterLast(delimiter, notFoundValue: str);
+
+		/// <returns>
+		/// the substring of <paramref name="str"/> after the last occurrence of <paramref name="delimiter"/>, or
+		/// <paramref name="notFoundValue"/> if not found
+		/// </returns>
+		public static string SubstringAfterLast(this string str, char delimiter, string notFoundValue)
+		{
+			var index = str.LastIndexOf(delimiter);
+			return index < 0 ? notFoundValue : str.Substring(index + 1, str.Length - index - 1);
+		}
+
 		/// <returns>
 		/// the substring of <paramref name="str"/> before the first occurrence of <paramref name="delimiter"/>, or
 		/// the original <paramref name="str"/> if not found

src/BizHawk.Emulation.Common/Base Implementations/CallbackBasedTraceBuffer.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 
 namespace BizHawk.Emulation.Common
 {
@@ -58,7 +57,7 @@ namespace BizHawk.Emulation.Common
 
 				if (_sink != null)
 				{
-					var scope = DebuggableCore.MemoryCallbacks.AvailableScopes.First(); // This will be an issue when cores use this trace buffer and utilize multiple scopes
+					var scope = DebuggableCore.MemoryCallbacks.AvailableScopes[0]; // This will be an issue when cores use this trace buffer and utilize multiple scopes
 					DebuggableCore.MemoryCallbacks.Add(new TracingMemoryCallback(TraceFromCallback, scope));
 				}
 			}

src/BizHawk.Emulation.Common/Base Implementations/MemoryDomainList.cs

@@ -30,7 +30,7 @@ namespace BizHawk.Emulation.Common
 
 		public MemoryDomain MainMemory
 		{
-			get => _mainMemory ?? this.First();
+			get => _mainMemory ?? this[0];
 			set => _mainMemory = value;
 		}
 

src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.IInputPollable.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
+
+using BizHawk.Common.StringExtensions;
 using BizHawk.Emulation.Common;
 
 namespace BizHawk.Emulation.Cores.Arcades.MAME
@@ -31,10 +32,8 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 			{
 				if (portField != string.Empty)
 				{
-					string[] substrings = portField.Split(',');
+					var tag = portField.SubstringBefore(',');
-					string tag = substrings.First();
+					var field = portField.SubstringAfterLast(',');
-					string field = substrings.Last();
-
 					_fieldsPorts.Add(field, tag);
 					MAMEController.BoolButtons.Add(field);
 				}

src/BizHawk.Emulation.Cores/Computers/AmstradCPC/Hardware/Display/AmstradGateArray.cs

@@ -1007,18 +1007,8 @@ namespace BizHawk.Emulation.Cores.Computers.AmstradCPC
 					var padPos = pad * -1;
 					var excessL = padPos / 2;
 					var excessR = excessL + (padPos % 2);
-					for (int i = 0; i < excessL; i++)
+					for (var i = 0; i < excessL; i++) lCop.RemoveAt(0);
-					{
+					for (var i = 0; i < excessL; i++) lCop.RemoveAt(lCop.Count - 1); //TODO should be using excessR?
-						var lThing = lCop.First();
-
-						lCop.Remove(lThing);
-					}
-					for (int i = 0; i < excessL; i++)
-					{
-						var lThing = lCop.Last();
-
-						lCop.Remove(lThing);
-					}
 				}
 
 				var lPad = pad / 2;

src/BizHawk.Emulation.Cores/Computers/AmstradCPC/Media/Disk/FloppyDisk.cs

@@ -662,7 +662,7 @@ namespace BizHawk.Emulation.Cores.Computers.AmstradCPC
 							for (int i = 0; i < size - ActualDataByteLength; i++)
 							{
 								//l.Add(SectorData[i]);
-								l.Add(SectorData.Last());
+								l.Add(SectorData[SectorData.Length - 1]);
 							}
 
 							return l.ToArray();

src/BizHawk.Emulation.Cores/Computers/AmstradCPC/Media/Tape/CDT/CdtConverter.cs

@@ -367,7 +367,7 @@ namespace BizHawk.Emulation.Cores.Computers.AmstradCPC
 			_position += blockLen;
 
 			// generate PAUSE block
-			CreatePauseBlock(_datacorder.DataBlocks.Last());
+			CreatePauseBlock(_datacorder.DataBlocks[_datacorder.DataBlocks.Count - 1]);
 		}
 
 		/*              length: [0F,10,11]+12
@@ -427,7 +427,7 @@ namespace BizHawk.Emulation.Cores.Computers.AmstradCPC
 			_position += blockLen;
 
 			// generate PAUSE block
-			CreatePauseBlock(_datacorder.DataBlocks.Last());
+			CreatePauseBlock(_datacorder.DataBlocks[_datacorder.DataBlocks.Count - 1]);
 		}
 
 		/*              length: 04
@@ -551,7 +551,7 @@ namespace BizHawk.Emulation.Cores.Computers.AmstradCPC
 			_position += blockLen;
 
 			// generate PAUSE block
-			CreatePauseBlock(_datacorder.DataBlocks.Last());
+			CreatePauseBlock(_datacorder.DataBlocks[_datacorder.DataBlocks.Count - 1]);
 		}
 
 		/*              length: [05,06,07]+08
@@ -657,7 +657,7 @@ namespace BizHawk.Emulation.Cores.Computers.AmstradCPC
 			_datacorder.DataBlocks.Add(t);
 
 			// generate PAUSE block
-			CreatePauseBlock(_datacorder.DataBlocks.Last());
+			CreatePauseBlock(_datacorder.DataBlocks[_datacorder.DataBlocks.Count - 1]);
 		}
 
 		/*              length: [00,01,02,03]+04
@@ -728,7 +728,7 @@ namespace BizHawk.Emulation.Cores.Computers.AmstradCPC
 			_datacorder.DataBlocks.Add(t);
 
 			// generate PAUSE block
-			CreatePauseBlock(_datacorder.DataBlocks.Last());
+			CreatePauseBlock(_datacorder.DataBlocks[_datacorder.DataBlocks.Count - 1]);
 		}
 
 		/*              length: [00,01,02,03]+04
@@ -880,7 +880,7 @@ namespace BizHawk.Emulation.Cores.Computers.AmstradCPC
 			_position += 2;
 
 			// generate PAUSE block
-			CreatePauseBlock(_datacorder.DataBlocks.Last());
+			CreatePauseBlock(_datacorder.DataBlocks[_datacorder.DataBlocks.Count - 1]);
 
 		}
 

src/BizHawk.Emulation.Cores/Computers/Commodore64/C64.cs

@@ -252,7 +252,7 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64
 		private void Init(VicType initRegion, BorderType borderType, SidType sidType, TapeDriveType tapeDriveType, DiskDriveType diskDriveType)
 		{
 			// Force certain drive types to be available depending on ROM type
-			var rom = _roms.First();
+			var rom = _roms[0];
 
 			switch (C64FormatFinder.GetFormat(rom))
 			{

src/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Media/Disk/FloppyDisk.cs

@@ -665,7 +665,7 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
 							for (int i = 0; i < size - ActualDataByteLength; i++)
 							{
 								//l.Add(SectorData[i]);
-								l.Add(SectorData.Last());
+								l.Add(SectorData[SectorData.Length - 1]);
 							}
 
 							return l.ToArray();

src/BizHawk.Emulation.Cores/Consoles/Atari/2600/Atari2600.cs

@@ -1,7 +1,7 @@
 using System;
-using System.Linq;
 
 using BizHawk.Common;
+using BizHawk.Common.StringExtensions;
 using BizHawk.Emulation.Common;
 
 namespace BizHawk.Emulation.Cores.Atari.Atari2600
@@ -81,7 +81,7 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 			{
 				Name = _game.Name,
 				System = VSystemID.Raw.A26,
-				MetaData = "m=" + _mapper.GetType().ToString().Split('.').Last(),
+				MetaData = "m=" + _mapper.GetType().ToString().SubstringAfterLast('.'),
 				Hash = SHA1Checksum.ComputeDigestHex(Rom),
 				Region = _game.Region,
 				Status = RomStatus.Unknown

src/BizHawk.Emulation.Cores/Consoles/Fairchild/ChannelF/ChannelF.cs

@@ -33,7 +33,7 @@ namespace BizHawk.Emulation.Cores.Consoles.ChannelF
 			var bios02 = CoreComm.CoreFileProvider.GetFirmwareOrThrow(new("ChannelF", "ChannelF_sl131254"));
 			//var bios02 = CoreComm.CoreFileProvider.GetFirmwareOrThrow(new("ChannelF", "ChannelF_sl90025"));
 
-			Cartridge = VesCartBase.Configure(_gameInfo.First(), _files.First());
+			Cartridge = VesCartBase.Configure(_gameInfo[0], _files[0]);
 
 			BIOS01 = bios01;
 			BIOS02 = bios02;			

src/BizHawk.Tests/Common/StringExtensions/StringExtensionTests.cs

@@ -67,6 +67,15 @@ namespace BizHawk.Tests.Common.StringExtensions
 			Assert.AreEqual(qrs, string.Empty.SubstringAfter("abc", qrs));
 		}
 
+		[TestMethod]
+		public void TestSubstringAfterLast()
+		{
+			// fewer tests for SubstringAfterLast as its implementation should match SubstringAfter, save for using LastIndexOf
+
+			Assert.AreEqual("ab", "abcdabcdab".SubstringAfterLast('d', qrs));
+			Assert.AreEqual(qrs, "abcdabcdab".SubstringAfterLast('x', qrs));
+		}
+
 		[TestMethod]
 		public void TestSubstringBefore()
 		{