C#: Properly dispose diagnostic writer objects

Author: tamasvajk

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/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
@@ -351,6 +351,20 @@ protected BuildScript AutobuildFailure() =>
             }
         });
 
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                (diagnostics as IDisposable)?.Dispose();
+            }
+        }
+
         /// <summary>
         /// Value of CODEQL_EXTRACTOR_<LANG>_ROOT environment variable.
         /// </summary>