Add some nullable attributes for net4x compatibility

Part of a fix for issue #1067

MimeKit/MimeKit.csproj

@@ -95,6 +95,8 @@
  <Compile Remove="Cryptography\LdapUri.cs" />
  <Compile Remove="Utils\OptimizedOrdinalComparer.cs" />
  <Compile Include="Utils\OptimizedOrdinalComparer.cs" Condition=" $(TargetFramework.StartsWith('net4')) Or '$(TargetFramework)' == 'netstandard2.0' " />
+ <Compile Remove="NullableAttributes.cs" />
+ <Compile Include="NullableAttributes.cs" Condition=" $(TargetFramework.StartsWith('net4')) Or '$(TargetFramework)' == 'netstandard2.0' " />
  </ItemGroup>
 
 </Project>

MimeKit/MimeKitLite.csproj

@@ -71,6 +71,8 @@
  <Compile Include="Cryptography\AuthenticationResults.cs" />
  <Compile Remove="Utils\OptimizedOrdinalComparer.cs" />
  <Compile Include="Utils\OptimizedOrdinalComparer.cs" Condition=" $(TargetFramework.StartsWith('net4')) Or '$(TargetFramework)' == 'netstandard2.0' " />
+ <Compile Remove="NullableAttributes.cs" />
+ <Compile Include="NullableAttributes.cs" Condition=" $(TargetFramework.StartsWith('net4')) Or '$(TargetFramework)' == 'netstandard2.0' " />
  </ItemGroup>
 
 </Project>

MimeKit/NullableAttributes.cs

@@ -0,0 +1,119 @@
+//
+// NullableAttributes.cs
+//
+// Author: Jeffrey Stedfast <[email protected]>
+//
+// Copyright (c) 2013-2024 .NET Foundation and Contributors
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+//
+
+namespace System.Diagnostics.CodeAnalysis {
+ [AttributeUsage (AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property, Inherited = false)]
+ sealed class AllowNullAttribute : Attribute
+ {
+ public AllowNullAttribute () { }
+ }
+
+ [AttributeUsage (AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property, Inherited = false)]
+ sealed class DisallowNullAttribute : Attribute
+ {
+ public DisallowNullAttribute () { }
+ }
+
+ [AttributeUsage (AttributeTargets.Parameter, Inherited = false)]
+ sealed class DoesNotReturnAttribute : Attribute
+ {
+ public DoesNotReturnAttribute () { }
+ }
+
+ [AttributeUsage (AttributeTargets.Parameter, Inherited = false)]
+ sealed class DoesNotReturnIfAttribute : Attribute
+ {
+ public DoesNotReturnIfAttribute (bool parameterValue) => ParameterValue = parameterValue;
+
+ public bool ParameterValue { get; }
+ }
+
+ [AttributeUsage (AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, Inherited = false)]
+ sealed class MaybeNullAttribute : Attribute
+ {
+ public MaybeNullAttribute () { }
+ }
+
+ [AttributeUsage (AttributeTargets.Parameter, Inherited = false)]
+ sealed class MaybeNullWhenAttribute : Attribute
+ {
+ public MaybeNullWhenAttribute (bool returnValue) => ReturnValue = returnValue;
+
+ public bool ReturnValue { get; }
+ }
+
+ [AttributeUsage (AttributeTargets.Method | AttributeTargets.Property | AttributeTargets.ReturnValue, AllowMultiple = true, Inherited = false)]
+ sealed class MemberNotNullAttribute : Attribute
+ {
+ public MemberNotNullAttribute (string member) => Members = new string[] { member };
+
+ public MemberNotNullAttribute (params string[] members) => Members = members;
+
+ public string[] Members { get; }
+ }
+
+ [AttributeUsage (AttributeTargets.Method | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
+ sealed class MemberNotNullWhenAttribute : Attribute
+ {
+ public MemberNotNullWhenAttribute (bool returnValue, string member)
+ {
+ Members = new string[] { member };
+ ReturnValue = returnValue;
+ }
+
+ public MemberNotNullWhenAttribute (bool returnValue, string[] members)
+ {
+ Members = members;
+ ReturnValue = returnValue;
+ }
+
+ public string[] Members { get; }
+
+ public bool ReturnValue { get; }
+ }
+
+ [AttributeUsage (AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, Inherited = false)]
+ sealed class NotNullAttribute : Attribute
+ {
+ public NotNullAttribute () { }
+ }
+
+ [AttributeUsage (AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, AllowMultiple = true, Inherited = false)]
+ sealed class NotNullIfNotNullAttribute : Attribute
+ {
+ public NotNullIfNotNullAttribute (string parameterName) => ParameterName = parameterName;
+
+ public string ParameterName { get; }
+ }
+
+ [AttributeUsage (AttributeTargets.Parameter, Inherited = false)]
+ sealed class NotNullWhenAttribute : Attribute
+ {
+ public NotNullWhenAttribute (bool returnValue) => ReturnValue = returnValue;
+
+ public bool ReturnValue { get; }
+ }
+}