Fix String.IndexOf with empty string input (#11587)

diff --git a/src/mscorlib/src/System/Globalization/CompareInfo.Windows.cs b/src/mscorlib/src/System/Globalization/CompareInfo.Windows.cs
index d20bb9f..143a6bc 100644 (file)
--- a/src/mscorlib/src/System/Globalization/CompareInfo.Windows.cs
+++ b/src/mscorlib/src/System/Globalization/CompareInfo.Windows.cs
@@ -199,7 +199,7 @@ namespace System.Globalization
             {
                 if (matchLengthPtr != null)
                     *matchLengthPtr = 0;
-                return 0;
+                return startIndex;
             }
 
             if (source.Length == 0)