Remove dead case from string.Compare (#18345)

1 files changed, 2 insertions, 4 deletions

diff --git a/src/System.Private.CoreLib/shared/System/String.Comparison.cs b/src/System.Private.CoreLib/shared/System/String.Comparison.cs
index 99efcbe5aa..3ddc90a502 100644
--- a/src/System.Private.CoreLib/shared/System/String.Comparison.cs
+++ b/src/System.Private.CoreLib/shared/System/String.Comparison.cs
@@ -415,11 +415,9 @@ namespace System
                 case StringComparison.Ordinal:
                     return CompareOrdinalHelper(strA, indexA, lengthA, strB, indexB, lengthB);
 
-                case StringComparison.OrdinalIgnoreCase:
-                    return CompareInfo.CompareOrdinalIgnoreCase(strA, indexA, lengthA, strB, indexB, lengthB);
-
                 default:
-                    throw new ArgumentException(SR.NotSupported_StringComparison, nameof(comparisonType));
+                    Debug.Assert(comparisonType == StringComparison.OrdinalIgnoreCase); // CheckStringComparison validated these earlier
+                    return CompareInfo.CompareOrdinalIgnoreCase(strA, indexA, lengthA, strB, indexB, lengthB);
             }
         }