C#: add option and code generation for null reference types (#20242)

.github/workflows/test_csharp.yml

@@ -35,7 +35,8 @@ jobs:
             cd csharp &&
             dotnet restore src/Google.Protobuf.sln &&
             dotnet build -c Release src/Google.Protobuf.sln &&
-            dotnet test -c Release -f net6.0 src/Google.Protobuf.Test/Google.Protobuf.Test.csproj"
+            dotnet test -c Release -f net6.0 src/Google.Protobuf.Test/Google.Protobuf.Test.csproj &&
+            dotnet test -c Release -f net8.0 src/Google.Protobuf.Test/Google.Protobuf.Test.csproj"
 
       - name: Clear bazel between docker instances
         run: sudo rm -rf _build .repository-cache
@@ -60,7 +61,7 @@ jobs:
       - name: Setup dotnet
         uses: actions/setup-dotnet@3447fd6a9f9e57506b15f895c5b76d3b197dc7c2 # v3.2.0
         with:
-          dotnet-version: '6.0.x'
+          dotnet-version: '8.0.x'
 
       # Workaround for incompatibility between gcloud and windows-2019 runners.
       - name: Install Python
@@ -94,15 +95,15 @@ jobs:
         # (we want to avoid references to ~/.nuget that won't be available in the subsequent docker run)
         uses: protocolbuffers/protobuf-ci/docker@v4
         with:
-          image: mcr.microsoft.com/dotnet/sdk:6.0.100-bullseye-slim
+          image: mcr.microsoft.com/dotnet/sdk:8.0.100-bookworm-slim
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           command: >-
             /bin/bash -cex '
             DOTNET_CLI_TELEMETRY_OPTOUT=true
             DOTNET_SKIP_FIRST_TIME_EXPERIENCE=true
-            dotnet publish -c Release -f net6.0 /workspace/csharp/src/Google.Protobuf.Test/Google.Protobuf.Test.csproj'
+            dotnet publish -c Release /workspace/csharp/src/Google.Protobuf.Test/Google.Protobuf.Test.csproj'
 
-      - name: Use an actual aarch64 docker image to run protobuf C# tests with an emulator
+      - name: Use an actual aarch64 docker image to run protobuf C# tests with an emulator (.NET 6)
         # "dotnet vstest" allows running tests from a pre-built project.
         # * mount the protobuf root as /work to be able to access the crosscompiled files
         # * to avoid running the process inside docker as root (which can pollute the workspace with files owned by root), we force
@@ -119,3 +120,21 @@ jobs:
             DOTNET_CLI_TELEMETRY_OPTOUT=true
             DOTNET_SKIP_FIRST_TIME_EXPERIENCE=true
             dotnet vstest /workspace/csharp/src/Google.Protobuf.Test/bin/Release/net6.0/publish/Google.Protobuf.Test.dll'
+
+      - name: Use an actual aarch64 docker image to run protobuf C# tests with an emulator (.NET 8)
+        # "dotnet vstest" allows running tests from a pre-built project.
+        # * mount the protobuf root as /work to be able to access the crosscompiled files
+        # * to avoid running the process inside docker as root (which can pollute the workspace with files owned by root), we force
+        #   running under current user's UID and GID. To be able to do that, we need to provide a home directory for the user
+        #   otherwise the UID would be homeless under the docker container and pip install wouldn't work. For simplicity,
+        #   we just run map the user's home to a throwaway temporary directory
+        uses: protocolbuffers/protobuf-ci/docker@v4
+        with:
+          image: mcr.microsoft.com/dotnet/sdk:8.0.100-bookworm-slim-arm64v8
+          skip-staleness-check: true
+          credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
+          command: >-
+            /bin/bash -cex '
+            DOTNET_CLI_TELEMETRY_OPTOUT=true
+            DOTNET_SKIP_FIRST_TIME_EXPERIENCE=true
+            dotnet vstest /workspace/csharp/src/Google.Protobuf.Test/bin/Release/net8.0/publish/Google.Protobuf.Test.dll'

csharp/generate_protos.sh

@@ -45,6 +45,7 @@ $PROTOC -Isrc --csharp_out=csharp/src/Google.Protobuf \
     src/google/protobuf/type.proto \
     src/google/protobuf/wrappers.proto \
     src/google/protobuf/compiler/plugin.proto
+# We are NOT generating NRT variants for Google.Protobuf right now to avoid breaking/unexpected changes!
 
 # Test protos
 # Note that this deliberately does *not* include old_extensions1.proto
@@ -81,13 +82,47 @@ $PROTOC -Isrc -I. \
     src/google/protobuf/unittest_legacy_features.proto \
     src/google/protobuf/unittest_proto3_optional.proto \
     src/google/protobuf/unittest_retention.proto
+$PROTOC -Isrc -I. \
+    --experimental_allow_proto3_optional \
+    --experimental_editions \
+    --csharp_out=csharp/src/Google.Protobuf.Test.TestProtos/Nrt \
+    --csharp_opt=enable_nrt,file_extension=.pb.nrt.cs \
+    conformance/test_protos/test_messages_edition2023.proto \
+    csharp/protos/map_unittest_proto3.proto \
+    csharp/protos/unittest_issues.proto \
+    csharp/protos/unittest_custom_options_proto3.proto \
+    csharp/protos/unittest_proto3.proto \
+    csharp/protos/unittest_import_proto3.proto \
+    csharp/protos/unittest_import_public_proto3.proto \
+    csharp/protos/unittest.proto \
+    csharp/protos/unittest_import.proto \
+    csharp/protos/unittest_import_public.proto \
+    csharp/protos/unittest_issue6936_a.proto \
+    csharp/protos/unittest_issue6936_b.proto \
+    csharp/protos/unittest_issue6936_c.proto \
+    csharp/protos/unittest_selfreferential_options.proto \
+    editions/golden/test_messages_proto3_editions.proto \
+    editions/golden/test_messages_proto2_editions.proto \
+    src/google/protobuf/unittest_well_known_types.proto \
+    src/google/protobuf/test_messages_proto3.proto \
+    src/google/protobuf/test_messages_proto2.proto \
+    src/google/protobuf/unittest_features.proto \
+    src/google/protobuf/unittest_legacy_features.proto \
+    src/google/protobuf/unittest_proto3_optional.proto \
+    src/google/protobuf/unittest_retention.proto
 
 # AddressBook sample protos
 $PROTOC -Iexamples -Isrc --csharp_out=csharp/src/AddressBook \
     --csharp_opt=file_extension=.pb.cs \
     examples/addressbook.proto
+$PROTOC -Iexamples -Isrc --csharp_out=csharp/src/AddressBook/Nrt \
+    --csharp_opt=enable_nrt,file_extension=.pb.nrt.cs \
+    examples/addressbook.proto
 
 # Conformance tests
 $PROTOC -I. --csharp_out=csharp/src/Google.Protobuf.Conformance \
     --csharp_opt=file_extension=.pb.cs \
     conformance/conformance.proto
+$PROTOC -I. --csharp_out=csharp/src/Google.Protobuf.Conformance/Nrt \
+    --csharp_opt=enable_nrt,file_extension=.pb.nrt.cs \
+    conformance/conformance.proto

csharp/install_dotnet_sdk.ps1

@@ -17,4 +17,4 @@ Invoke-WebRequest -Uri $InstallScriptUrl -OutFile $InstallScriptPath
 # The SDK versions to install should be kept in sync with versions
 # installed by kokoro/linux/dockerfile/test/csharp/Dockerfile
 &$InstallScriptPath -Version 3.1.415
-&$InstallScriptPath -Version 6.0.100
+&$InstallScriptPath -Version 8.0.100

csharp/src/AddressBook/AddressBook.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
     <OutputType>Exe</OutputType>
     <StartupObject>Google.Protobuf.Examples.AddressBook.Program</StartupObject>
     <IsPackable>False</IsPackable>
@@ -11,4 +11,17 @@
     <ProjectReference Include="..\Google.Protobuf\Google.Protobuf.csproj" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Compile Remove="**/*.pb*.cs" />
+    <None Include="**/*.pb*.cs" />
+  </ItemGroup>
+
+  <ItemGroup Condition=" '$(TargetFramework)' != 'net8.0' ">
+    <Compile Include="**/*.pb.cs" />
+  </ItemGroup>
+
+  <ItemGroup Condition=" '$(TargetFramework)' == 'net8.0' ">
+    <Compile Include="**/*.pb.nrt.cs" />
+  </ItemGroup>
+
 </Project>