C#: Properly dispose diagnostic writer objects

Author: tamasvajk

cpp/autobuilder/Semmle.Autobuild.Cpp.Tests/BuildScripts.cs

@@ -203,6 +203,8 @@ internal class TestDiagnosticWriter : IDiagnosticsWriter
         public IList<DiagnosticMessage> Diagnostics { get; } = new List<DiagnosticMessage>();
 
         public void AddEntry(DiagnosticMessage message) => this.Diagnostics.Add(message);
+
+        public void Dispose() { }
     }
 
     /// <summary>

cpp/autobuilder/Semmle.Autobuild.Cpp/Program.cs

@@ -17,7 +17,7 @@ static int Main()
                 try
                 {
                     Console.WriteLine("CodeQL C++ autobuilder");
-                    var builder = new CppAutobuilder(actions, options);
+                    using var builder = new CppAutobuilder(actions, options);
                     return builder.AttemptBuild();
                 }
                 catch (InvalidEnvironmentException ex)

csharp/autobuilder/Semmle.Autobuild.CSharp.Tests/BuildScripts.cs

@@ -218,6 +218,8 @@ internal class TestDiagnosticWriter : IDiagnosticsWriter
         public IList<DiagnosticMessage> Diagnostics { get; } = new List<DiagnosticMessage>();
 
         public void AddEntry(DiagnosticMessage message) => this.Diagnostics.Add(message);
+
+        public void Dispose() { }
     }
 
     /// <summary>

csharp/autobuilder/Semmle.Autobuild.CSharp/Program.cs

@@ -17,7 +17,7 @@ public static int Main()
                 try
                 {
                     Console.WriteLine("CodeQL C# autobuilder");
-                    var builder = new CSharpAutobuilder(actions, options);
+                    using var builder = new CSharpAutobuilder(actions, options);
                     return builder.AttemptBuild();
                 }
                 catch (InvalidEnvironmentException ex)

csharp/autobuilder/Semmle.Autobuild.Shared/Autobuilder.cs

@@ -92,7 +92,7 @@ public interface IAutobuilder<out TAutobuildOptions> where TAutobuildOptions : A
     /// The overall design is intended to be extensible so that in theory,
     /// it should be possible to add new build rules without touching this code.
     /// </summary>
-    public abstract class Autobuilder<TAutobuildOptions> : IAutobuilder<TAutobuildOptions> where TAutobuildOptions : AutobuildOptionsShared
+    public abstract class Autobuilder<TAutobuildOptions> : IDisposable, IAutobuilder<TAutobuildOptions> where TAutobuildOptions : AutobuildOptionsShared
     {
         /// <summary>
         /// Full file paths of files found in the project directory, as well as
@@ -370,6 +370,20 @@ protected BuildScript AutobuildFailure() =>
             }
         });
 
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                diagnostics?.Dispose();
+            }
+        }
+
         /// <summary>
         /// Value of CODEQL_EXTRACTOR_<LANG>_ROOT environment variable.
         /// </summary>

csharp/extractor/Semmle.Util/ToolStatusPage.cs

@@ -182,7 +182,7 @@ public DiagnosticMessage(
     /// <summary>
     /// Provides the ability to write diagnostic messages to some output.
     /// </summary>
-    public interface IDiagnosticsWriter
+    public interface IDiagnosticsWriter : IDisposable
     {
         /// <summary>
         /// Adds <paramref name="message" /> as a new diagnostics entry.
@@ -195,7 +195,7 @@ public interface IDiagnosticsWriter
     /// A wrapper around an underlying <see cref="StreamWriter" /> which allows
     /// <see cref="DiagnosticMessage" /> objects to be serialized to it.
     /// </summary>
-    public sealed class DiagnosticsStream : IDiagnosticsWriter, IDisposable
+    public sealed class DiagnosticsStream : IDiagnosticsWriter
     {
         private readonly JsonSerializer serializer;
         private readonly StreamWriter writer;