Fix `DEBUG` not being defined in C# `DebugOpt` configuration

Directory.Build.props

@@ -41,10 +41,15 @@
     <RID>$(RID)-$(PlatformTarget)</RID>
   </PropertyGroup>
 
-  <PropertyGroup Condition="'$(CPPSHARP_RELEASE)' != 'true'">
+  <PropertyGroup Condition="'$(Configuration)' == 'Debug'">
+      <DebugSymbols>true</DebugSymbols>
+      <DebugType>full</DebugType>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)' == 'DebugOpt'">
       <DebugSymbols>true</DebugSymbols>
       <DebugType>full</DebugType>
       <Optimize>false</Optimize>
+      <DefineConstants>DEBUG</DefineConstants>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(DotNetCmd)' == 'dotnet' AND $(IsWindows)">
@@ -56,4 +61,9 @@
     <Copy SourceFiles="$(TargetDir)$(TargetFileName)" DestinationFolder="$(PackageDir)ref\$(GlobalTargetFramework)" Condition="'$(ProduceReferenceAssembly)' == 'true' AND '$(RID)' == 'win-x64'" />
     <Copy SourceFiles="$(TargetPath)" DestinationFolder="$(PackageDir)runtimes\$(RID)\lib\$(GlobalTargetFramework)" />
   </Target>
+
+  <Target Name="ValidateCPPSHARPRelease" BeforeTargets="Build">
+      <Error Condition="'$(CPPSHARP_RELEASE)' == 'true' AND '$(Configuration)' != 'Release'"
+             Text="Configuration must be 'Release' when CPPSHARP_RELEASE is 'true'." />
+  </Target>
 </Project>

src/AST/CppSharp.AST.csproj

@@ -1,7 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>netstandard2.1</TargetFramework>
-    <PlatformTarget>AnyCPU</PlatformTarget>
     <ProduceReferenceAssembly>true</ProduceReferenceAssembly>
     <IsPackable>true</IsPackable>
   </PropertyGroup>

src/Core/CppSharp.csproj

@@ -1,7 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>netstandard2.1</TargetFramework>
-    <PlatformTarget>AnyCPU</PlatformTarget>
     <ProduceReferenceAssembly>true</ProduceReferenceAssembly>
     <IsPackable>true</IsPackable>
   </PropertyGroup>

src/Generator/Generators/MSBuildGenerator.cs

@@ -24,7 +24,7 @@ namespace CppSharp.Generators
             Write($@"
 <Project Sdk=""Microsoft.NET.Sdk"">
   <PropertyGroup>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFramework>netstandard2.1</TargetFramework>
     <PlatformTarget>{(Context.TargetInfo.PointerWidth == 64 ? "x64" : "x86")}</PlatformTarget>
     <OutputPath>{Options.OutputDir}</OutputPath>
     <DocumentationFile>{module.LibraryName}.xml</DocumentationFile>

src/Runtime/CppSharp.Runtime.csproj

@@ -2,8 +2,7 @@
   <PropertyGroup>
     <LangVersion>7.3</LangVersion>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <TargetFramework>netstandard2.0</TargetFramework>
-    <PlatformTarget>AnyCPU</PlatformTarget>
+    <TargetFramework>netstandard2.1</TargetFramework>
     <ProduceReferenceAssembly>true</ProduceReferenceAssembly>
     <IsPackable>true</IsPackable>
   </PropertyGroup>