remaining changes

Author: hrrrrustic

src/libraries/Common/src/Interop/Unix/Interop.Errors.cs

@@ -130,7 +130,7 @@ internal ErrorInfo(Error error)
             _rawErrno = -1;
         }
 
-        internal Error Error
+        internal readonly Error Error
         {
             get { return _error; }
         }

src/libraries/Common/src/Interop/Unix/System.Net.Security.Native/Interop.GssBuffer.cs

@@ -16,7 +16,7 @@ internal struct GssBuffer : IDisposable
             internal ulong _length;
             internal IntPtr _data;
 
-            internal int Copy(byte[] destination, int offset)
+            internal readonly int Copy(byte[] destination, int offset)
             {
                 Debug.Assert(destination != null, "target destination cannot be null");
                 Debug.Assert((offset >= 0 && offset < destination.Length) || destination.Length == 0, "invalid offset " + offset);
@@ -38,7 +38,7 @@ internal int Copy(byte[] destination, int offset)
                 return sourceLength;
             }
 
-            internal byte[] ToByteArray()
+            internal readonly byte[] ToByteArray()
             {
                 if (_data == IntPtr.Zero || _length == 0)
                 {
@@ -51,7 +51,7 @@ internal byte[] ToByteArray()
                 return destination;
             }
 
-            internal unsafe ReadOnlySpan<byte> Span => (_data != IntPtr.Zero && _length != 0) ?
+            internal unsafe readonly ReadOnlySpan<byte> Span => (_data != IntPtr.Zero && _length != 0) ?
                 new ReadOnlySpan<byte>(_data.ToPointer(), checked((int)_length)) :
                 default;
 

src/libraries/Common/src/Interop/Windows/Advapi32/Interop.PERF_INFO.cs

@@ -97,7 +97,7 @@ internal struct SYSTEMTIME
             internal short wSecond;
             internal short wMilliseconds;
 
-            public override string ToString()
+            public override readonly string ToString()
             {
                 return "[SYSTEMTIME: "
                 + wDay.ToString(CultureInfo.CurrentCulture) + "/" + wMonth.ToString(CultureInfo.CurrentCulture) + "/" + wYear.ToString(CultureInfo.CurrentCulture)

src/libraries/Common/src/Interop/Windows/Crypt32/Interop.CRYPT_BIT_BLOB.cs

@@ -15,7 +15,7 @@ internal struct CRYPT_BIT_BLOB
             internal IntPtr pbData;
             internal int cUnusedBits;
 
-            internal byte[] ToByteArray()
+            internal readonly byte[] ToByteArray()
             {
                 int numBytes = cbData;
                 byte[] data = new byte[numBytes];

src/libraries/Common/src/Interop/Windows/Crypt32/Interop.FindOidInfo.cs

@@ -21,15 +21,15 @@ internal struct CRYPT_OID_INFO
             public int cbData;
             public IntPtr pbData;
 
-            public string? OID
+            public readonly string? OID
             {
                 get
                 {
                     return Marshal.PtrToStringAnsi(pszOID);
                 }
             }
 
-            public string? Name
+            public readonly string? Name
             {
                 get
                 {

src/libraries/Common/src/Interop/Windows/Gdi32/Interop.RECT.cs

@@ -16,7 +16,7 @@ public struct RECT
             public int right;
             public int bottom;
 
-            public Size Size => new Size(right - left, bottom - top);
+            public readonly Size Size => new Size(right - left, bottom - top);
         }
     }
 }

src/libraries/Common/src/Interop/Windows/Interop.LongFileTime.cs

@@ -22,6 +22,6 @@ internal struct LongFileTime
         internal long TicksSince1601;
 #pragma warning restore CS0649
 
-        internal DateTimeOffset ToDateTimeOffset() => new DateTimeOffset(DateTime.FromFileTimeUtc(TicksSince1601));
+        internal readonly DateTimeOffset ToDateTimeOffset() => new DateTimeOffset(DateTime.FromFileTimeUtc(TicksSince1601));
     }
 }

src/libraries/Common/src/Interop/Windows/IpHlpApi/Interop.NetworkInformation.cs

@@ -58,7 +58,7 @@ internal struct IpSocketAddress
             internal IntPtr address;
             internal int addressLength;
 
-            internal IPAddress MarshalIPAddress()
+            internal readonly IPAddress MarshalIPAddress()
             {
                 // Determine the address family used to create the IPAddress.
                 AddressFamily family = (addressLength > Internals.SocketAddress.IPv4AddressSize)

src/libraries/Common/src/Interop/Windows/Kernel32/Interop.FILE_TIME.cs

@@ -18,9 +18,9 @@ internal FILE_TIME(long fileTime)
                 dwHighDateTime = (uint)(fileTime >> 32);
             }
 
-            internal long ToTicks() => ((long)dwHighDateTime << 32) + dwLowDateTime;
-            internal DateTime ToDateTimeUtc() => DateTime.FromFileTimeUtc(ToTicks());
-            internal DateTimeOffset ToDateTimeOffset() => DateTimeOffset.FromFileTime(ToTicks());
+            internal readonly long ToTicks() => ((long)dwHighDateTime << 32) + dwLowDateTime;
+            internal readonly DateTime ToDateTimeUtc() => DateTime.FromFileTimeUtc(ToTicks());
+            internal readonly DateTimeOffset ToDateTimeOffset() => DateTimeOffset.FromFileTime(ToTicks());
         }
     }
 }

src/libraries/Common/src/Interop/Windows/Kernel32/Interop.TimeZone.cs

@@ -18,7 +18,7 @@ internal struct SYSTEMTIME
             internal ushort Second;
             internal ushort Milliseconds;
 
-            internal bool Equals(in SYSTEMTIME other) =>
+            internal readonly bool Equals(in SYSTEMTIME other) =>
                     Year == other.Year &&
                     Month == other.Month &&
                     DayOfWeek == other.DayOfWeek &&
@@ -42,7 +42,7 @@ internal unsafe struct TIME_DYNAMIC_ZONE_INFORMATION
             internal fixed char TimeZoneKeyName[128];
             internal byte DynamicDaylightTimeDisabled;
 
-            internal string GetTimeZoneKeyName()
+            internal readonly string GetTimeZoneKeyName()
             {
                 fixed (char* p = TimeZoneKeyName)
                     return new string(p);
@@ -68,13 +68,13 @@ internal TIME_ZONE_INFORMATION(in TIME_DYNAMIC_ZONE_INFORMATION dtzi)
                     *pTo = *(TIME_ZONE_INFORMATION*)pFrom;
             }
 
-            internal string GetStandardName()
+            internal readonly string GetStandardName()
             {
                 fixed (char* p = StandardName)
                     return new string(p);
             }
 
-            internal string GetDaylightName()
+            internal readonly string GetDaylightName()
             {
                 fixed (char* p = DaylightName)
                     return new string(p);

src/libraries/Common/src/Interop/Windows/NtDll/Interop.FILE_FULL_DIR_INFORMATION.cs

@@ -54,7 +54,7 @@ public struct FILE_FULL_DIR_INFORMATION
             public uint EaSize;
 
             private char _fileName;
-            public unsafe ReadOnlySpan<char> FileName { get { fixed (char* c = &_fileName) { return new ReadOnlySpan<char>(c, (int)FileNameLength / sizeof(char)); } } }
+            public unsafe readonly ReadOnlySpan<char> FileName { get { fixed (char* c = &_fileName) { return new ReadOnlySpan<char>(c, (int)FileNameLength / sizeof(char)); } } }
 
             /// <summary>
             /// Gets the next info pointer or null if there are no more.

src/libraries/Common/src/Interop/Windows/Ole32/Interop.STATSTG.cs

@@ -59,7 +59,7 @@ internal struct STATSTG
             public uint grfStateBits;
             public uint reserved;
 
-            public string? GetName() => Marshal.PtrToStringUni(pwcsName);
+            public readonly string? GetName() => Marshal.PtrToStringUni(pwcsName);
 
             /// <summary>
             /// Caller is responsible for freeing the name memory.

src/libraries/Common/src/Interop/Windows/SspiCli/Interop.SSPI.cs

@@ -23,7 +23,7 @@ internal struct CredHandle
             private IntPtr dwLower;
             private IntPtr dwUpper;
 
-            public bool IsZero
+            public readonly bool IsZero
             {
                 [MethodImpl(MethodImplOptions.AggressiveInlining)]
                 get
@@ -38,7 +38,7 @@ internal void SetToInvalid()
                 dwUpper = IntPtr.Zero;
             }
 
-            public override string ToString()
+            public override readonly string ToString()
             {
                 { return dwLower.ToString("x") + ":" + dwUpper.ToString("x"); }
             }

src/libraries/Common/src/System/MutableDecimal.cs

@@ -23,13 +23,13 @@ internal struct MutableDecimal
 
         public bool IsNegative
         {
-            get { return (Flags & SignMask) != 0; }
+            readonly get { return (Flags & SignMask) != 0; }
             set { Flags = (Flags & ~SignMask) | (value ? SignMask : 0); }
         }
 
         public int Scale
         {
-            get { return (byte)(Flags >> ScaleShift); }
+            readonly get { return (byte)(Flags >> ScaleShift); }
             set { Flags = (Flags & ~ScaleMask) | ((uint)value << ScaleShift); }
         }