Check source and destination spans overlap in TryNormalize method (#118047)

Co-authored-by: Stephen Toub <[email protected]>

Author: tarekgh

src/libraries/System.Private.CoreLib/src/System/Globalization/Normalization.cs

@@ -44,6 +44,11 @@ internal static bool TryNormalize(ReadOnlySpan<char> source, Span<char> destinat
         {
             CheckNormalizationForm(normalizationForm);
 
+            if (source.Overlaps(destination))
+            {
+                ThrowHelper.ThrowArgumentException(ExceptionResource.InvalidOperation_SpanOverlappedOperation);
+            }
+
             // In Invariant mode we assume all characters are normalized because we don't support any linguistic operations on strings.
             // If it's ASCII && one of the 4 main forms, then it's already normalized.
             if (GlobalizationMode.Invariant || Ascii.IsValid(source))

src/libraries/System.Runtime/tests/System.Globalization.Extensions.Tests/Normalization/StringNormalizationTests.cs

@@ -126,6 +126,11 @@ public void Normalize_Invalid()
 
             AssertExtensions.Throws<ArgumentException>("strInput", () => "\uD800\uD800".Normalize()); // Invalid surrogate pair
             AssertExtensions.Throws<ArgumentException>("source", () => "\uD800\uD800".AsSpan().TryNormalize(destination, out int charsWritten)); // Invalid surrogate pair
+
+            char[] overlappingDestination = new char[5] { 'a', 'b', 'c', 'd', 'e' };
+            Assert.Throws<ArgumentException>(() => overlappingDestination.AsSpan().TryNormalize(overlappingDestination.AsSpan(), out int charsWritten, NormalizationForm.FormC));
+            Assert.Throws<ArgumentException>(() => overlappingDestination.AsSpan(0, 3).TryNormalize(overlappingDestination.AsSpan(), out int charsWritten, NormalizationForm.FormC));
+            Assert.Throws<ArgumentException>(() => overlappingDestination.AsSpan(4).TryNormalize(overlappingDestination.AsSpan(), out int charsWritten, NormalizationForm.FormC));
         }
 
         [Fact]