Fix Color Color const field initialization accessing the Color type

src/Compilers/CSharp/Portable/Binder/Binder_Expressions.cs

@@ -7547,6 +7547,11 @@ private BoundExpression BindLeftIdentifierOfPotentialColorColorMemberAccess(Iden
                                 Debug.Assert(!leftType.IsDynamic());
                                 Debug.Assert(IsPotentialColorColorReceiver(left, leftType));
 
+                                if (leftSymbol is SourceFieldSymbolWithSyntaxReference fieldLeft)
+                                {
+                                    ConstantFieldsInProgress.RemoveIfLastDependency(fieldLeft);
+                                }
+
                                 // NOTE: ReplaceTypeOrValueReceiver will call CheckValue explicitly.
                                 boundValue = BindToNaturalType(boundValue, valueDiagnostics);
                                 return new BoundTypeOrValueExpression(left,

src/Compilers/CSharp/Portable/Binder/Binder_Invocation.cs

@@ -1989,6 +1989,16 @@ private BoundExpression ReplaceTypeOrValueReceiver(BoundExpression receiver, boo
                     }
                     else
                     {
+                        // If we resort to rebinding back to the field, we attempt to add the dependency back
+                        if (typeOrValue.Data.ValueExpression.ExpressionSymbol is SourceFieldSymbolWithSyntaxReference sourceField
+                            && sourceField.IsConst)
+                        {
+                            if (!ConstantFieldsInProgress.IsEmpty)
+                            {
+                                ConstantFieldsInProgress.AddDependency(sourceField);
+                            }
+                        }
+
                         diagnostics.AddRange(typeOrValue.Data.ValueDiagnostics);
                         return CheckValue(typeOrValue.Data.ValueExpression, BindValueKind.RValue, diagnostics);
                     }

src/Compilers/CSharp/Portable/Binder/ConstantFieldsInProgress.cs

@@ -6,7 +6,6 @@
 
 using System.Collections.Generic;
 using Microsoft.CodeAnalysis.CSharp.Symbols;
-using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CSharp
 {
@@ -20,6 +19,13 @@ internal sealed class ConstantFieldsInProgress
         private readonly SourceFieldSymbol _fieldOpt;
         private readonly HashSet<SourceFieldSymbolWithSyntaxReference> _dependencies;
 
+        /// <summary>
+        /// Stores the last dependency that was added to the set. This is used to check if
+        /// the dependency that was added is not after all a dependency after successful rebinding
+        /// in Color Color resolution, i.e. `public const Color Color = Color.Red;`
+        /// </summary>
+        private SourceFieldSymbolWithSyntaxReference _lastDependency;
+
         internal static readonly ConstantFieldsInProgress Empty = new ConstantFieldsInProgress(null, null);
 
         internal ConstantFieldsInProgress(
@@ -38,6 +44,16 @@ public bool IsEmpty
         internal void AddDependency(SourceFieldSymbolWithSyntaxReference field)
         {
             _dependencies.Add(field);
+            _lastDependency = field;
+        }
+
+        internal void RemoveIfLastDependency(SourceFieldSymbolWithSyntaxReference field)
+        {
+            if (_lastDependency is not null && _lastDependency == (object)field)
+            {
+                _dependencies.Remove(_lastDependency);
+                _lastDependency = null;
+            }
         }
     }
 }

src/Compilers/CSharp/Test/Semantic/Semantics/ColorColorTests.cs

@@ -2368,6 +2368,108 @@ instance void .ctor () cil managed
             compilation.VerifyDiagnostics();
         }
 
+        [WorkItem("https://github.com/dotnet/roslyn/issues/45739")]
+        [Fact]
+        public void ConstFieldEnum()
+        {
+            const string source = @"
+using Color2 = Color;
+
+enum Color
+{
+    Red,
+    Green,
+    Blue,
+    Yellow,
+}
+
+class M
+{
+    public const Color Color = Color.Red;
+    public const Color2 Color2 = Color2.Yellow;
+}
+
+class Program
+{
+    static void Main()
+    {
+        System.Console.Write(M.Color == Color.Red);
+        System.Console.Write(M.Color2 == Color.Yellow);
+    }
+}
+";
+
+            CompileAndVerify(source, expectedOutput: "TrueTrue")
+                .VerifyDiagnostics();
+        }
+
+        [WorkItem("https://github.com/dotnet/roslyn/issues/45739")]
+        [Fact]
+        public void ConstFieldPrimitives()
+        {
+            const string source = @"
+using System;
+using SystemChar = System.Char;
+
+class M
+{
+    public const Int32 Int32 = Int32.MaxValue;
+    public const SystemChar SystemChar = SystemChar.MaxValue;
+}
+
+class Program
+{
+    static void Main()
+    {
+        System.Console.Write(M.Int32 == Int32.MaxValue);
+        System.Console.Write(M.SystemChar == SystemChar.MaxValue);
+    }
+}
+";
+
+            CompileAndVerify(source, expectedOutput: "TrueTrue")
+                .VerifyDiagnostics();
+        }
+
+        [WorkItem("https://github.com/dotnet/roslyn/issues/45739")]
+        [Fact]
+        public void ConstFieldPrimitivesActualCircular()
+        {
+            string source = @"
+using System;
+using SystemChar = System.Char;
+
+class M
+{
+    public const Int32 Int32 = Int32.Increment();
+    public const SystemChar SystemChar = SystemChar.Increment();
+}
+
+public static class Extensions
+{
+    public static int Increment(this int i) => i + 1;
+    public static char Increment(this ref char c) => ++c;
+}
+";
+
+            var compilation = CreateCompilation(source);
+
+            compilation.VerifyDiagnostics(
+                // (7,24): error CS0110: The evaluation of the constant value for 'M.Int32' involves a circular definition
+                //     public const Int32 Int32 = Int32.Increment();
+                Diagnostic(ErrorCode.ERR_CircConstValue, "Int32").WithArguments("M.Int32").WithLocation(7, 24),
+                // (7,32): error CS0133: The expression being assigned to 'M.Int32' must be constant
+                //     public const Int32 Int32 = Int32.Increment();
+                Diagnostic(ErrorCode.ERR_NotConstantExpression, "Int32.Increment()").WithArguments("M.Int32").WithLocation(7, 32),
+                // (8,29): error CS0110: The evaluation of the constant value for 'M.SystemChar' involves a circular definition
+                //     public const SystemChar SystemChar = SystemChar.Increment();
+                Diagnostic(ErrorCode.ERR_CircConstValue, "SystemChar").WithArguments("M.SystemChar").WithLocation(8, 29),
+                // (8,42): error CS1510: A ref or out value must be an assignable variable
+                //     public const SystemChar SystemChar = SystemChar.Increment();
+                Diagnostic(ErrorCode.ERR_RefLvalueExpected, "SystemChar").WithLocation(8, 42)
+                );
+        }
+
         [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/71039")]
         public void ConstInAttributes_NoCycle_01()
         {