[Java.Interop] Use PublicApiAnalyzers to ensure we do not break API (#1170)

Fixes: #1169
Context: dotnet/android@76ab8b2dotnet/android@76ab8b2c mentions:
> Now that we are in the .NET `TargetFramework` world we also need
> to ensure we do not *add* any new API to a Target Framework once it
> has shipped. A `TargetFramework` is essentially a contract that we
> cannot change. (Imagine if you had different minor versions of .NET
> on your local machine and CI machine, what works on one should work
> on the other.)
This prevents an issue where a user on `.NET 8.0.300` uses a method
that isn't available to their coworker or CI on `.NET 8.0.100`.
This logical argument also applies to `Java.Interop.dll`.
Enable Microsoft's [PublicApiAnalyzers][0] for `Java.Interop.dll`.
([PublicApiAnalyzers documentation][1].) This ensures that we don't
add new API once we've shipped `Java.Interop.dll` for a given
.NET version.
Update `build-tools/jnienv-gen` so that `JniEnvironment.g.cs` enables
nullable reference types. This allows us to *avoid* disabling RS0041.
Co-authored-by: Jonathan Pryor <jonpryor@vt.edu>
[0]: https://github.com/dotnet/roslyn-analyzers/tree/ace28a1039d09626a94d3b0f8ce69e547ca2bcbf/src/PublicApiAnalyzers
[1]: https://github.com/dotnet/roslyn-analyzers/blob/ace28a1039d09626a94d3b0f8ce69e547ca2bcbf/src/PublicApiAnalyzers/PublicApiAnalyzers.Help.md

Author: jpobst

build-tools/jnienv-gen/Generator.cs

@@ -86,6 +86,7 @@ static void GenerateFile (TextWriter o)
 o.WriteLine("// Generated file; DO NOT EDIT!");
 o.WriteLine("//");
 o.WriteLine("// To make changes, edit monodroid/tools/jnienv-gen-interop and rerun");
+o.WriteLine("#nullable enable");
 o.WriteLine();
 o.WriteLine("#if !FEATURE_JNIENVIRONMENT_SAFEHANDLES && !FEATURE_JNIENVIRONMENT_JI_INTPTRS && !FEATURE_JNIENVIRONMENT_JI_PINVOKES && !FEATURE_JNIENVIRONMENT_XA_INTPTRS && !FEATURE_JNIENVIRONMENT_JI_FUNCTION_POINTERS");
 o.WriteLine("#define FEATURE_JNIENVIRONMENT_JI_PINVOKES");
@@ -255,7 +256,7 @@ static void GenerateJniNativeInterfaceInvoker (TextWriter o, HandleStyle style)
 if(e.Prebind)
 o.WriteLine("\t\tpublic readonly {0} {1};\n",d,e.Name);
 else{
-o.WriteLine("\t\t{0} _{1};",d,e.Name);
+o.WriteLine("\t\t{0}? _{1};",d,e.Name);
 o.WriteLine("\t\tpublic {0} {1} {{",d,e.Name);
 o.WriteLine("\t\t\tget {");
 o.WriteLine("\t\t\t\tif (_{0} == null)\n\t\t\t\t\t{1}",e.Name,Initialize(e,"_",d));
@@ -551,7 +552,7 @@ static void RaiseException (TextWriter o, JniFunction entry, HandleStyle style)
 return;
 
 o.WriteLine();
-o.WriteLine("\t\t\tException __e = JniEnvironment.GetExceptionForLastThrowable ({0});",
+o.WriteLine("\t\t\tException? __e = JniEnvironment.GetExceptionForLastThrowable ({0});",
 (style==HandleStyle.JIIntPtrPinvokeWithErrors||style==HandleStyle.JIFunctionPtrWithErrors)
 ?"thrown"
 :"");
@@ -1127,7 +1128,7 @@ public override string[] GetMarshalToManagedStatements (HandleStyle style, strin
 caseHandleStyle.JIFunctionPtrWithErrors:
 returnnew[]{
 string.Format("if ({0} == IntPtr.Zero)",variable),
-string.Format("\treturn null;"),
+string.Format($"\tthrow new InvalidOperationException (\"Should not be reached; `{entry.Name}` should have thrown!\");"),
 string.Format("return new {0} ({1}, {2}, {3}, isStatic: {4});",type,entry.Parameters[1].Name,entry.Parameters[2].Name,variable,IsStatic?"true":"false"),
 };
 caseHandleStyle.XAIntPtr:

src/Java.Interop/Java.Interop.csproj

@@ -88,18 +88,11 @@
  <DependentUpon>JniPeerMembers.JniInstanceMethods_Invoke.tt</DependentUpon>
  </Compile>
  </ItemGroup>
- <ProjectExtensions>
- <MonoDevelop>
- <Properties>
- <Policies>
- <VersionControlPolicy>
- <CommitMessageStyleIndent="&#x9;"LineAlign="0"IncludeDirectoryPaths="True" />
- </VersionControlPolicy>
- </Policies>
- </Properties>
- </MonoDevelop>
- </ProjectExtensions>
  <ItemGroup>
+ <PackageReferenceInclude="Microsoft.CodeAnalysis.PublicApiAnalyzers"Version="3.3.4">
+ <PrivateAssets>all</PrivateAssets>
+ <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+ </PackageReference>
  <PackageReferenceInclude="Microsoft.SourceLink.GitHub"PrivateAssets="All" />
  </ItemGroup>
  <ImportProject="Java.Interop.targets" />

src/Java.Interop/Java.Interop/JavaObjectArray.cs

@@ -11,6 +11,7 @@ public class JavaObjectArray<T> : JavaArray<T>
 {
 internalstaticreadonlyValueMarshalerInstance=newValueMarshaler();
 
+[SuppressMessage("ApiDesign","RS0022:Constructor make noninheritable base class inheritable",Justification="Existing public API")]
 publicJavaObjectArray(refJniObjectReferencehandle,JniObjectReferenceOptionsoptions)
 :base(refhandle,options)
 {
@@ -29,20 +30,23 @@ static JniObjectReference NewArray (int length)
 }
 }
 
+[SuppressMessage("ApiDesign","RS0022:Constructor make noninheritable base class inheritable",Justification="Existing public API")]
 publicunsafeJavaObjectArray(intlength)
 :this(ref*InvalidJniObjectReference,JniObjectReferenceOptions.None)
 {
 varpeer=NewArray(CheckLength(length));
 Construct(refpeer,JniObjectReferenceOptions.CopyAndDispose);
 }
 
+[SuppressMessage("ApiDesign","RS0022:Constructor make noninheritable base class inheritable",Justification="Existing public API")]
 publicJavaObjectArray(IList<T>value)
 :this(CheckLength(value))
 {
 for(inti=0;i<value.Count;++i)
 SetElementAt(i,value[i]);
 }
 
+[SuppressMessage("ApiDesign","RS0022:Constructor make noninheritable base class inheritable",Justification="Existing public API")]
 publicJavaObjectArray(IEnumerable<T>value)
 :this(ToList(value))
 {

src/Java.Interop/Java.Interop/JniEnvironment.Types.cs

@@ -262,7 +262,7 @@ public static void RegisterNatives (JniObjectReference type, JniNativeMethodRegi
 }
 #endif // DEBUG && NETCOREAPP
 
-intr=_RegisterNatives(type,methods,numMethods);
+intr=_RegisterNatives(type,methods??Array.Empty<JniNativeMethodRegistration>(),numMethods);
 
 if(r!=0){
 thrownewInvalidOperationException(

src/Java.Interop/Java.Interop/JniValueMarshaler.cs

@@ -49,6 +49,7 @@ public struct JniValueMarshalerState : IEquatable<JniValueMarshalerState> {
 publicIJavaPeerable?PeerableValue{get;privateset;}
 publicobject?Extra{get;privateset;}
 
+[SuppressMessage("ApiDesign","RS0026:Do not add multiple public overloads with optional parameters",Justification="Existing public API")]
 publicJniValueMarshalerState(JniArgumentValuejniArgumentValue,object?extra=null)
 {
 JniArgumentValue=jniArgumentValue;
@@ -57,6 +58,7 @@ public JniValueMarshalerState (JniArgumentValue jniArgumentValue, object? extra
 Extra=extra;
 }
 
+[SuppressMessage("ApiDesign","RS0026:Do not add multiple public overloads with optional parameters",Justification="Existing public API")]
 publicJniValueMarshalerState(JniObjectReferencereferenceValue,object?extra=null)
 {
 JniArgumentValue=newJniArgumentValue(referenceValue);
@@ -65,6 +67,7 @@ public JniValueMarshalerState (JniObjectReference referenceValue, object? extra
 Extra=extra;
 }
 
+[SuppressMessage("ApiDesign","RS0026:Do not add multiple public overloads with optional parameters",Justification="Existing public API")]
 publicJniValueMarshalerState(IJavaPeerable?peerableValue,object?extra=null)
 {
 PeerableValue=peerableValue;