Use 'AsSpan' over 'Substring' in 'System.Private.Xml' (#48277)

NewellClark · stephentoub · web-flow · commit 5c2b21bb3f0b · 2021-02-14T22:47:28.000-05:00
* Fix violation in System.Private.Xml

- Prefer 'AsSpan' over 'Substring' when span-based overloads are available.

* Update src/libraries/System.Private.Xml/src/System/Xml/Serialization/CodeIdentifier.cs

Apply suggested optimization.

Co-authored-by: Stephen Toub &lt;stoub@microsoft.com&gt;

Co-authored-by: Stephen Toub &lt;stoub@microsoft.com&gt;
diff --git a/src/libraries/System.Private.Xml/src/System/Xml/Serialization/CodeIdentifier.cs b/src/libraries/System.Private.Xml/src/System/Xml/Serialization/CodeIdentifier.cs
@@ -283,7 +283,7 @@ private static void EscapeKeywords(string identifier, StringBuilder sb)
             {
                 if (separator >= 0)
                 {
-                    sb.Append(originalIdentifier.Substring(separator, 1));
+                    sb.Append(originalIdentifier[separator]);
                 }
                 separator++;
                 separator += names[i].Length;

Original file line number	Diff line number	Diff line change
`@@ -283,7 +283,7 @@ private static void EscapeKeywords(string identifier, StringBuilder sb)`
`283`	`283`	`{`
`284`	`284`	`if (separator >= 0)`
`285`	`285`	`{`
`286`		`- sb.Append(originalIdentifier.Substring(separator, 1));`
	`286`	`+ sb.Append(originalIdentifier[separator]);`
`287`	`287`	`}`
`288`	`288`	`separator++;`
`289`	`289`	`separator += names[i].Length;`