Clean up a few minor Span-related uses (#22038)

Some unnecessary Span to ReadOnlySpan casts.
Some places where new Span(...).Slice(...) can be replaced with AsSpan(...).
Etc.

3 files changed, 4 insertions, 4 deletions

diff --git a/src/System.Private.CoreLib/src/System/Enum.cs b/src/System.Private.CoreLib/src/System/Enum.cs
index c8c1fa11fc..e085517f58 100644
--- a/src/System.Private.CoreLib/src/System/Enum.cs
+++ b/src/System.Private.CoreLib/src/System/Enum.cs
@@ -269,7 +269,7 @@ namespace System
             const int SeparatorStringLength = 2; // ", "
             string result = string.FastAllocateString(checked(resultLength + (SeparatorStringLength * (foundItemsCount - 1))));
 
-            Span<char> resultSpan = MemoryMarshal.CreateSpan(ref result.GetRawStringData(), result.Length);
+            Span<char> resultSpan = new Span<char>(ref result.GetRawStringData(), result.Length);
             string name = names[foundItems[--foundItemsCount]];
             name.AsSpan().CopyTo(resultSpan);
             resultSpan = resultSpan.Slice(name.Length);
diff --git a/src/System.Private.CoreLib/src/System/StubHelpers.cs b/src/System.Private.CoreLib/src/System/StubHelpers.cs
index 3464d5a3ed..8bf9c56f06 100644
--- a/src/System.Private.CoreLib/src/System/StubHelpers.cs
+++ b/src/System.Private.CoreLib/src/System/StubHelpers.cs
@@ -45,7 +45,7 @@ namespace System.StubHelpers
 
         internal static char ConvertToManaged(byte nativeChar)
         {
-            Span<byte> bytes = new Span<byte>(ref nativeChar, 1);
+            var bytes = new ReadOnlySpan<byte>(ref nativeChar, 1);
             string str = Encoding.Default.GetString(bytes);
             return str[0];
         }
@@ -204,7 +204,7 @@ namespace System.StubHelpers
 
             byte* pBytes = (byte*)pNative;
             int nbBytes = string.strlen(pBytes);
-            sb.ReplaceBufferUtf8Internal(new Span<byte>(pBytes, nbBytes));
+            sb.ReplaceBufferUtf8Internal(new ReadOnlySpan<byte>(pBytes, nbBytes));
         }
     }
 
diff --git a/src/System.Private.CoreLib/src/System/Text/StringBuilder.CoreCLR.cs b/src/System.Private.CoreLib/src/System/Text/StringBuilder.CoreCLR.cs
index 716c5cccaf..63afe45f32 100644
--- a/src/System.Private.CoreLib/src/System/Text/StringBuilder.CoreCLR.cs
+++ b/src/System.Private.CoreLib/src/System/Text/StringBuilder.CoreCLR.cs
@@ -38,7 +38,7 @@ namespace System.Text
             m_ChunkOffset = 0;
         }
 
-        internal void ReplaceBufferUtf8Internal(Span<byte> source)
+        internal void ReplaceBufferUtf8Internal(ReadOnlySpan<byte> source)
         {
             if (source.Length > m_MaxCapacity)
                 throw new ArgumentOutOfRangeException("capacity", SR.ArgumentOutOfRange_Capacity);