Fixed renting buffer from pool in INumberBase (#102755)

Author: gfoidl

src/libraries/System.Private.CoreLib/src/System/Numerics/INumberBase.cs

@@ -306,15 +306,15 @@ static virtual TSelf Parse(ReadOnlySpan<byte> utf8Text, NumberStyles style, IFor
             scoped Span<char> utf16Text;
             int textMaxCharCount = Encoding.UTF8.GetMaxCharCount(utf8Text.Length);
 
-            if (textMaxCharCount < 256)
+            if (textMaxCharCount <= 256)
             {
                 utf16TextArray = null;
                 utf16Text = stackalloc char[256];
             }
             else
             {
                 utf16TextArray = ArrayPool<char>.Shared.Rent(textMaxCharCount);
-                utf16Text = utf16TextArray.AsSpan(0, textMaxCharCount);
+                utf16Text = utf16TextArray;
             }
 
             OperationStatus utf8TextStatus = Utf8.ToUtf16(utf8Text, utf16Text, out _, out int utf16TextLength, replaceInvalidSequences: false);
@@ -440,15 +440,15 @@ static virtual bool TryParse(ReadOnlySpan<byte> utf8Text, NumberStyles style, IF
             scoped Span<char> utf16Text;
             int textMaxCharCount = Encoding.UTF8.GetMaxCharCount(utf8Text.Length);
 
-            if (textMaxCharCount < 256)
+            if (textMaxCharCount <= 256)
             {
                 utf16TextArray = null;
                 utf16Text = stackalloc char[256];
             }
             else
             {
                 utf16TextArray = ArrayPool<char>.Shared.Rent(textMaxCharCount);
-                utf16Text = utf16TextArray.AsSpan(0, textMaxCharCount);
+                utf16Text = utf16TextArray;
             }
 
             OperationStatus utf8TextStatus = Utf8.ToUtf16(utf8Text, utf16Text, out _, out int utf16TextLength, replaceInvalidSequences: false);
@@ -486,15 +486,15 @@ bool IUtf8SpanFormattable.TryFormat(Span<byte> utf8Destination, out int bytesWri
             scoped Span<char> utf16Destination;
             int destinationMaxCharCount = Encoding.UTF8.GetMaxCharCount(utf8Destination.Length);
 
-            if (destinationMaxCharCount < 256)
+            if (destinationMaxCharCount <= 256)
             {
                 utf16DestinationArray = null;
                 utf16Destination = stackalloc char[256];
             }
             else
             {
                 utf16DestinationArray = ArrayPool<char>.Shared.Rent(destinationMaxCharCount);
-                utf16Destination = utf16DestinationArray.AsSpan(0, destinationMaxCharCount);
+                utf16Destination = utf16DestinationArray;
             }
 
             if (!TryFormat(utf16Destination, out int charsWritten, format, provider))
@@ -542,15 +542,15 @@ static TSelf IUtf8SpanParsable<TSelf>.Parse(ReadOnlySpan<byte> utf8Text, IFormat
             scoped Span<char> utf16Text;
             int textMaxCharCount = Encoding.UTF8.GetMaxCharCount(utf8Text.Length);
 
-            if (textMaxCharCount < 256)
+            if (textMaxCharCount <= 256)
             {
                 utf16TextArray = null;
                 utf16Text = stackalloc char[256];
             }
             else
             {
                 utf16TextArray = ArrayPool<char>.Shared.Rent(textMaxCharCount);
-                utf16Text = utf16TextArray.AsSpan(0, textMaxCharCount);
+                utf16Text = utf16TextArray;
             }
 
             OperationStatus utf8TextStatus = Utf8.ToUtf16(utf8Text, utf16Text, out _, out int utf16TextLength, replaceInvalidSequences: false);
@@ -589,15 +589,15 @@ static bool IUtf8SpanParsable<TSelf>.TryParse(ReadOnlySpan<byte> utf8Text, IForm
             scoped Span<char> utf16Text;
             int textMaxCharCount = Encoding.UTF8.GetMaxCharCount(utf8Text.Length);
 
-            if (textMaxCharCount < 256)
+            if (textMaxCharCount <= 256)
             {
                 utf16TextArray = null;
                 utf16Text = stackalloc char[256];
             }
             else
             {
                 utf16TextArray = ArrayPool<char>.Shared.Rent(textMaxCharCount);
-                utf16Text = utf16TextArray.AsSpan(0, textMaxCharCount);
+                utf16Text = utf16TextArray;
             }
 
             OperationStatus utf8TextStatus = Utf8.ToUtf16(utf8Text, utf16Text, out _, out int utf16TextLength, replaceInvalidSequences: false);