Adding C#, F#, VB to StringSyntaxAttribute

src/libraries/System.Private.CoreLib/src/System/Diagnostics/CodeAnalysis/StringSyntaxAttribute.cs

@@ -38,6 +38,9 @@ public StringSyntaxAttribute(string syntax, params object?[] arguments)
         /// <summary>The syntax identifier for strings containing composite formats for string formatting.</summary>
         public const string CompositeFormat = nameof(CompositeFormat);
 
+        /// <summary>The syntax identifier for strings containing C# code.</summary>
+        public const string CSharp = "C#";
+
         /// <summary>The syntax identifier for strings containing date format specifiers.</summary>
         public const string DateOnlyFormat = nameof(DateOnlyFormat);
 
@@ -47,6 +50,9 @@ public StringSyntaxAttribute(string syntax, params object?[] arguments)
         /// <summary>The syntax identifier for strings containing <see cref="Enum"/> format specifiers.</summary>
         public const string EnumFormat = nameof(EnumFormat);
 
+        /// <summary>The syntax identifier for strings containing F# code.</summary>
+        public const string FSharp = "F#";
+
         /// <summary>The syntax identifier for strings containing <see cref="Guid"/> format specifiers.</summary>
         public const string GuidFormat = nameof(GuidFormat);
 
@@ -68,6 +74,9 @@ public StringSyntaxAttribute(string syntax, params object?[] arguments)
         /// <summary>The syntax identifier for strings containing URIs.</summary>
         public const string Uri = nameof(Uri);
 
+        /// <summary>The syntax identifier for strings containing Visual Basic code.</summary>
+        public const string VisualBasic = "Visual Basic";
+
         /// <summary>The syntax identifier for strings containing XML.</summary>
         public const string Xml = nameof(Xml);
     }

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

@@ -9096,16 +9096,19 @@ public SetsRequiredMembersAttribute() { }
     public sealed partial class StringSyntaxAttribute : System.Attribute
     {
         public const string CompositeFormat = "CompositeFormat";
+        public const string CSharp = "C#";
         public const string DateOnlyFormat = "DateOnlyFormat";
         public const string DateTimeFormat = "DateTimeFormat";
         public const string EnumFormat = "EnumFormat";
+        public const string FSharp = "F#";
         public const string GuidFormat = "GuidFormat";
         public const string Json = "Json";
         public const string NumericFormat = "NumericFormat";
         public const string Regex = "Regex";
         public const string TimeOnlyFormat = "TimeOnlyFormat";
         public const string TimeSpanFormat = "TimeSpanFormat";
         public const string Uri = "Uri";
+        public const string VisualBasic = "Visual Basic";
         public const string Xml = "Xml";
         public StringSyntaxAttribute(string syntax) { }
         public StringSyntaxAttribute(string syntax, params object?[] arguments) { }

src/libraries/System.Runtime/tests/System.Runtime.Tests/System/Diagnostics/CodeAnalysis/StringSyntaxAttributeTests.cs

@@ -8,9 +8,12 @@ namespace System.Diagnostics.CodeAnalysis.Tests
     public sealed class StringSyntaxAttributeTests
     {
         [Theory]
+        [InlineData(StringSyntaxAttribute.CSharp)]
         [InlineData(StringSyntaxAttribute.DateTimeFormat)]
+        [InlineData(StringSyntaxAttribute.FSharp)]
         [InlineData(StringSyntaxAttribute.Json)]
         [InlineData(StringSyntaxAttribute.Regex)]
+        [InlineData(StringSyntaxAttribute.VisualBasic)]
         public void Ctor_Roundtrips(string syntax)
         {
             var attribute = new StringSyntaxAttribute(syntax);