Change accessibility of explicit implementations in interfaces to 'private'. (#35506)

src/Compilers/CSharp/Portable/Symbols/Source/ModifierUtils.cs

@@ -144,9 +144,9 @@ internal static DeclarationModifiers AdjustModifiersForAnInterfaceMember(Declara
 
             if ((mods & DeclarationModifiers.AccessibilityMask) == 0)
             {
-                if ((mods & DeclarationModifiers.Partial) == 0)
+                if ((mods & DeclarationModifiers.Partial) == 0 && !isExplicitInterfaceImplementation)
                 {
-                    mods |= isExplicitInterfaceImplementation ? DeclarationModifiers.Protected : DeclarationModifiers.Public;
+                    mods |= DeclarationModifiers.Public;
                 }
                 else
                 {

src/Compilers/CSharp/Portable/Symbols/Source/SourceEventSymbol.cs

@@ -423,7 +423,7 @@ private void CheckAccessibility(Location location, DiagnosticBag diagnostics, bo
                                                    DiagnosticBag diagnostics, out bool modifierErrors)
         {
             bool isInterface = this.ContainingType.IsInterface;
-            var defaultAccess = isInterface ? (explicitInterfaceImplementation ? DeclarationModifiers.Protected : DeclarationModifiers.Public) : DeclarationModifiers.Private;
+            var defaultAccess = isInterface && !explicitInterfaceImplementation ? DeclarationModifiers.Public : DeclarationModifiers.Private;
             var defaultInterfaceImplementationModifiers = DeclarationModifiers.None;
 
             // Check that the set of modifiers is allowed

src/Compilers/CSharp/Portable/Symbols/Source/SourceOrdinaryMethodSymbol.cs

@@ -831,7 +831,7 @@ private DeclarationModifiers MakeModifiers(SyntaxTokenList modifiers, MethodKind
         {
             bool isInterface = this.ContainingType.IsInterface;
             bool isExplicitInterfaceImplementation = methodKind == MethodKind.ExplicitInterfaceImplementation;
-            var defaultAccess = isInterface && modifiers.IndexOf(SyntaxKind.PartialKeyword) < 0 ? (isExplicitInterfaceImplementation ? DeclarationModifiers.Protected : DeclarationModifiers.Public) : DeclarationModifiers.Private;
+            var defaultAccess = isInterface && modifiers.IndexOf(SyntaxKind.PartialKeyword) < 0 && !isExplicitInterfaceImplementation ? DeclarationModifiers.Public : DeclarationModifiers.Private;
 
             // Check that the set of modifiers is allowed
             var allowedModifiers = DeclarationModifiers.Partial | DeclarationModifiers.Unsafe;

src/Compilers/CSharp/Portable/Symbols/Source/SourcePropertySymbol.cs

@@ -835,7 +835,7 @@ private void CheckAccessibility(Location location, DiagnosticBag diagnostics, bo
                                                    Location location, DiagnosticBag diagnostics, out bool modifierErrors)
         {
             bool isInterface = this.ContainingType.IsInterface;
-            var defaultAccess = isInterface ? (isExplicitInterfaceImplementation ? DeclarationModifiers.Protected : DeclarationModifiers.Public) : DeclarationModifiers.Private;
+            var defaultAccess = isInterface && !isExplicitInterfaceImplementation ? DeclarationModifiers.Public : DeclarationModifiers.Private;
 
             // Check that the set of modifiers is allowed
             var allowedModifiers = DeclarationModifiers.Unsafe;

src/Compilers/CSharp/Test/Symbol/Symbols/DefaultInterfaceImplementationTests.cs

@@ -29150,7 +29150,7 @@ private static void ValidateExplicitImplementation(MethodSymbol m1)
             Assert.False(m1.IsExtern);
             Assert.False(m1.IsAsync);
             Assert.False(m1.IsOverride);
-            Assert.Equal(Accessibility.Protected, m1.DeclaredAccessibility);
+            Assert.Equal(Accessibility.Private, m1.DeclaredAccessibility);
 
             if (m1.ContainingModule is PEModuleSymbol peModule)
             {
@@ -29703,7 +29703,7 @@ private static void ValidateExplicitExternImplementation(MethodSymbol m1)
             Assert.NotEqual(m1.OriginalDefinition is PEMethodSymbol, m1.IsExtern);
             Assert.False(m1.IsAsync);
             Assert.False(m1.IsOverride);
-            Assert.Equal(Accessibility.Protected, m1.DeclaredAccessibility);
+            Assert.Equal(Accessibility.Private, m1.DeclaredAccessibility);
 
             if (m1.ContainingModule is PEModuleSymbol peModule)
             {
@@ -29793,7 +29793,7 @@ void Validate2(MethodSymbol m1)
                 Assert.False(m1.IsExtern);
                 Assert.NotEqual(m1 is PEMethodSymbol, m1.IsAsync);
                 Assert.False(m1.IsOverride);
-                Assert.Equal(Accessibility.Protected, m1.DeclaredAccessibility);
+                Assert.Equal(Accessibility.Private, m1.DeclaredAccessibility);
 
                 if (m1.ContainingModule is PEModuleSymbol peModule)
                 {
@@ -32211,7 +32211,7 @@ private static void ValidateExplicitImplementation(PropertySymbol m1)
             Assert.False(m1.IsStatic);
             Assert.False(m1.IsExtern);
             Assert.False(m1.IsOverride);
-            Assert.Equal(Accessibility.Protected, m1.DeclaredAccessibility);
+            Assert.Equal(Accessibility.Private, m1.DeclaredAccessibility);
 
             ValidateAccessor(m1.GetMethod);
             ValidateAccessor(m1.SetMethod);
@@ -32829,7 +32829,7 @@ private static void ValidateExplicitExternImplementation(PropertySymbol m1)
             Assert.False(m1.IsStatic);
             Assert.NotEqual(m1.OriginalDefinition is PEPropertySymbol, m1.IsExtern);
             Assert.False(m1.IsOverride);
-            Assert.Equal(Accessibility.Protected, m1.DeclaredAccessibility);
+            Assert.Equal(Accessibility.Private, m1.DeclaredAccessibility);
 
             ValidateAccessor(m1.GetMethod);
             ValidateAccessor(m1.SetMethod);
@@ -34426,7 +34426,7 @@ private static void ValidateExplicitImplementation(EventSymbol m1)
             Assert.False(m1.IsStatic);
             Assert.False(m1.IsExtern);
             Assert.False(m1.IsOverride);
-            Assert.Equal(Accessibility.Protected, m1.DeclaredAccessibility);
+            Assert.Equal(Accessibility.Private, m1.DeclaredAccessibility);
 
             ValidateAccessor(m1.AddMethod);
             ValidateAccessor(m1.RemoveMethod);