Call String.Contains(char) from String.Contains(string) for single-ch…

…ar literals (#97632)
dotnet · Jan 29, 2024 · 9025846 · 9025846
1 parent 3eabd9a
commit 9025846
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/src/libraries/System.Private.CoreLib/src/System/String.Searching.cs b/src/libraries/System.Private.CoreLib/src/System/String.Searching.cs
@@ -13,6 +13,12 @@ public bool Contains(string value)
             if (value == null)
                 ThrowHelper.ThrowArgumentNullException(ExceptionArgument.value);
 
+            if (RuntimeHelpers.IsKnownConstant(value) && value.Length == 1)
+            {
+                // Call the char overload, e.g. Contains("X") -> Contains('X')
+                return Contains(value[0]);
+            }
+
             return SpanHelpers.IndexOf(
                 ref _firstChar,
                 Length,