Make String.{Try}CopyTo public

src/libraries/Common/src/System/Net/SocketAddress.cs

@@ -251,7 +251,7 @@ public override string ToString()
                 stackalloc char[256] :
                 new char[maxLength];
 
-            familyString.AsSpan().CopyTo(result);
+            familyString.CopyTo(result);
             int length = familyString.Length;
 
             result[length++] = ':';

src/libraries/Common/src/System/Text/ValueStringBuilder.cs

@@ -158,10 +158,9 @@ public void Insert(int index, string? s)
 
             int remaining = _pos - index;
             _chars.Slice(index, remaining).CopyTo(_chars.Slice(index + count));
-#if SYSTEM_PRIVATE_CORELIB
             s
-#else
-            s.AsSpan()
+#if !NET6_0_OR_GREATER
+                .AsSpan()
 #endif
                 .CopyTo(_chars.Slice(index));
             _pos += count;
@@ -210,10 +209,9 @@ private void AppendSlow(string s)
                 Grow(s.Length);
             }
 
-#if SYSTEM_PRIVATE_CORELIB
             s
-#else
-            s.AsSpan()
+#if !NET6_0_OR_GREATER
+                .AsSpan()
 #endif
                 .CopyTo(_chars.Slice(pos));
             _pos += s.Length;

src/libraries/Common/tests/Tests/System/StringTests.cs

@@ -482,6 +482,42 @@ public static void CopyTo_Invalid()
             AssertExtensions.Throws<ArgumentOutOfRangeException>("sourceIndex", () => s.CopyTo(0, dst, 0, 6));
         }
 
+        [Theory]
+        [InlineData("", 0)]
+        [InlineData("", 1)]
+        [InlineData("a", 1)]
+        [InlineData("a", 0)]
+        [InlineData("a", 2)]
+        [InlineData("abc", 2)]
+        [InlineData("abc", 3)]
+        [InlineData("abc", 4)]
+        [InlineData("Hello world", 20)]
+        public static void CopyTo_Span(string s, int destinationLength)
+        {
+            char[] destination = new char[destinationLength];
+
+            if (s.Length > destinationLength)
+            {
+                AssertExtensions.Throws<ArgumentException>("destination", () => s.CopyTo(destination));
+                Assert.All(destination, c => Assert.Equal(0, c));
+
+                Assert.False(s.TryCopyTo(destination));
+                Assert.All(destination, c => Assert.Equal(0, c));
+            }
+            else
+            {
+                s.CopyTo(destination);
+                Assert.Equal(s, new Span<char>(destination, 0, s.Length).ToString());
+                Assert.All(destination.AsSpan(s.Length).ToArray(), c => Assert.Equal(0, c));
+
+                Array.Clear(destination, 0, destination.Length);
+
+                Assert.True(s.TryCopyTo(destination));
+                Assert.Equal(s, new Span<char>(destination, 0, s.Length).ToString());
+                Assert.All(destination.AsSpan(s.Length).ToArray(), c => Assert.Equal(0, c));
+            }
+        }
+
         public static IEnumerable<object[]> Compare_TestData()
         {
             // CurrentCulture

src/libraries/System.Diagnostics.TextWriterTraceListener/src/System/Diagnostics/XmlWriterTraceListener.cs

@@ -71,14 +71,14 @@ public override void Fail(string? message, string? detailMessage)
             TraceEvent(null, SR.TraceAsTraceSource, TraceEventType.Error, 0, string.Create(length, (message, detailMessage),
             (dst, v) =>
             {
-                ReadOnlySpan<char> prefix = v.message;
+                string prefix = v.message;
                 prefix.CopyTo(dst);
 
                 if (v.detailMessage != null)
                 {
                     dst[prefix.Length] = ' ';
 
-                    ReadOnlySpan<char> detail = v.detailMessage;
+                    string detail = v.detailMessage;
                     detail.CopyTo(dst.Slice(prefix.Length + 1, detail.Length));
                 }
             }));

src/libraries/System.Private.CoreLib/src/System/String.cs

@@ -461,14 +461,11 @@ public unsafe void CopyTo(int sourceIndex, char[] destination, int destinationIn
                 elementCount: (uint)count);
         }
 
-        // TODO: https://github.com/dotnet/runtime/issues/51061
-        // Make these {Try}CopyTo methods public and use throughout dotnet/runtime.
-
         /// <summary>Copies the contents of this string into the destination span.</summary>
         /// <param name="destination">The span into which to copy this string's contents.</param>
         /// <exception cref="System.ArgumentException">The destination span is shorter than the source string.</exception>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal void CopyTo(Span<char> destination)
+        public void CopyTo(Span<char> destination)
         {
             if ((uint)Length <= (uint)destination.Length)
             {
@@ -484,7 +481,7 @@ internal void CopyTo(Span<char> destination)
         /// <param name="destination">The span into which to copy this string's contents.</param>
         /// <returns>true if the data was copied; false if the destination was too short to fit the contents of the string.</returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal bool TryCopyTo(Span<char> destination)
+        public bool TryCopyTo(Span<char> destination)
         {
             bool retVal = false;
             if ((uint)Length <= (uint)destination.Length)

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

@@ -35,7 +35,7 @@ public static string MakePascal(string identifier)
             {
                 return string.Create(identifier.Length, identifier, static (buffer, identifier) =>
                 {
-                    identifier.AsSpan().CopyTo(buffer);
+                    identifier.CopyTo(buffer);
                     buffer[0] = char.ToUpperInvariant(buffer[0]); // convert only first char to uppercase; leave all else as-is
                 });
             }
@@ -59,7 +59,7 @@ public static string MakeCamel(string identifier)
             {
                 return string.Create(identifier.Length, identifier, static (buffer, identifier) =>
                 {
-                    identifier.AsSpan().CopyTo(buffer);
+                    identifier.CopyTo(buffer);
                     buffer[0] = char.ToLowerInvariant(buffer[0]); // convert only first char to lowercase; leave all else as-is
                 });
             }

src/libraries/System.Runtime/ref/System.Runtime.cs

@@ -3632,6 +3632,7 @@ public unsafe String(sbyte* value, int startIndex, int length, System.Text.Encod
         [System.ObsoleteAttribute("This API should not be used to create mutable strings. See https://go.microsoft.com/fwlink/?linkid=2084035 for alternatives.")]
         public static System.String Copy(System.String str) { throw null; }
         public void CopyTo(int sourceIndex, char[] destination, int destinationIndex, int count) { }
+        public void CopyTo(System.Span<char> destination) { }
         public static System.String Create<TState>(int length, TState state, System.Buffers.SpanAction<char, TState> action) { throw null; }
         public bool EndsWith(char value) { throw null; }
         public bool EndsWith(System.String value) { throw null; }
@@ -3767,6 +3768,7 @@ public void CopyTo(int sourceIndex, char[] destination, int destinationIndex, in
         public System.String TrimStart() { throw null; }
         public System.String TrimStart(char trimChar) { throw null; }
         public System.String TrimStart(params char[]? trimChars) { throw null; }
+        public bool TryCopyTo(System.Span<char> destination) { throw null; }
     }
     public abstract partial class StringComparer : System.Collections.Generic.IComparer<string?>, System.Collections.Generic.IEqualityComparer<string?>, System.Collections.IComparer, System.Collections.IEqualityComparer
     {

src/libraries/System.Security.Cryptography.Encoding/src/System/Security/Cryptography/PemEncoding.cs

@@ -168,9 +168,9 @@ static ReadOnlySpan<char> WritePostEB(ReadOnlySpan<char> label, Span<char> desti
             {
                 int size = PostEBPrefix.Length + label.Length + Ending.Length;
                 Debug.Assert(destination.Length >= size);
-                PostEBPrefix.AsSpan().CopyTo(destination);
+                PostEBPrefix.CopyTo(destination);
                 label.CopyTo(destination.Slice(PostEBPrefix.Length));
-                Ending.AsSpan().CopyTo(destination.Slice(PostEBPrefix.Length + label.Length));
+                Ending.CopyTo(destination.Slice(PostEBPrefix.Length + label.Length));
                 return destination.Slice(0, size);
             }
         }

src/libraries/System.Security.Cryptography.X509Certificates/src/Internal/Cryptography/Pal.Unix/OpenSslX509ChainProcessor.cs

@@ -740,7 +740,7 @@ private static string UrlPathAppend(string baseUri, ReadOnlyMemory<char> resourc
                     (baseUri, resource),
                     (buf, st) =>
                     {
-                        st.baseUri.AsSpan().CopyTo(buf);
+                        st.baseUri.CopyTo(buf);
                         st.resource.Span.CopyTo(buf.Slice(st.baseUri.Length));
                     });
             }
@@ -750,7 +750,7 @@ private static string UrlPathAppend(string baseUri, ReadOnlyMemory<char> resourc
                 (baseUri, resource),
                 (buf, st) =>
                 {
-                    st.baseUri.AsSpan().CopyTo(buf);
+                    st.baseUri.CopyTo(buf);
                     buf[st.baseUri.Length] = '/';
                     st.resource.Span.CopyTo(buf.Slice(st.baseUri.Length + 1));
                 });

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonCamelCaseNamingPolicy.cs

@@ -15,7 +15,11 @@ public override string ConvertName(string name)
 #if BUILDING_INBOX_LIBRARY
             return string.Create(name.Length, name, (chars, name) =>
             {
-                name.AsSpan().CopyTo(chars);
+                name
+#if !NET6_0_OR_GREATER
+                .AsSpan()
+#endif
+                .CopyTo(chars);
                 FixCasing(chars);
             });
 #else

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexCharClass.cs

@@ -576,11 +576,11 @@ public static string ConvertOldStringsToClass(string set, string category)
                     span[FlagsIndex] = '\0';
                     span[SetLengthIndex] = (char)state.set.Length;
                     span[CategoryLengthIndex] = (char)state.category.Length;
-                    state.set.AsSpan().CopyTo(span.Slice(SetStartIndex));
+                    state.set.CopyTo(span.Slice(SetStartIndex));
                     index = SetStartIndex + state.set.Length;
                 }
 
-                state.category.AsSpan().CopyTo(span.Slice(index));
+                state.category.CopyTo(span.Slice(index));
             });
         }
 

src/libraries/System.Web.HttpUtility/src/System/Web/Util/Utf16StringValidator.cs

@@ -34,7 +34,7 @@ internal static string ValidateString(string input)
             // slow case: surrogates exist, so we need to validate them
             return string.Create(input.Length, (input, idxOfFirstSurrogate), (chars, state) =>
             {
-                state.input.AsSpan().CopyTo(chars);
+                state.input.CopyTo(chars);
                 for (int i = state.idxOfFirstSurrogate; i < chars.Length; i++)
                 {
                     char thisChar = chars[i];