Make method abstract and force subclasses to implement

src/Workspaces/Core/Portable/Workspace/Solution/SolutionCompilationState.CompilationAndGeneratorDriverTranslationAction.cs

@@ -5,43 +5,39 @@
 using System.Threading;
 using System.Threading.Tasks;
 
-namespace Microsoft.CodeAnalysis
+namespace Microsoft.CodeAnalysis;
+
+internal partial class SolutionCompilationState
 {
-    internal partial class SolutionCompilationState
+    /// <summary>
+    /// Represents a change that needs to be made to a <see cref="Compilation"/>, <see cref="GeneratorDriver"/>, or both in response to
+    /// some user edit.
+    /// </summary>
+    private abstract partial class CompilationAndGeneratorDriverTranslationAction
     {
+        public abstract Task<Compilation> TransformCompilationAsync(Compilation oldCompilation, CancellationToken cancellationToken);
+
         /// <summary>
-        /// Represents a change that needs to be made to a <see cref="Compilation"/>, <see cref="GeneratorDriver"/>, or both in response to
-        /// some user edit.
+        /// Whether or not <see cref="TransformCompilationAsync" /> can be called on Compilations that may contain
+        /// generated documents.
         /// </summary>
-        private abstract partial class CompilationAndGeneratorDriverTranslationAction
-        {
-            public virtual Task<Compilation> TransformCompilationAsync(Compilation oldCompilation, CancellationToken cancellationToken)
-            {
-                return Task.FromResult(oldCompilation);
-            }
-
-            /// <summary>
-            /// Whether or not <see cref="TransformCompilationAsync" /> can be called on Compilations that may contain
-            /// generated documents.
-            /// </summary>
-            /// <remarks>
-            /// Most translation actions add or remove a single syntax tree which means we can do the "same" change
-            /// to a compilation that contains the generated files and one that doesn't; however some translation actions
-            /// (like <see cref="ReplaceAllSyntaxTreesAction"/>) will unilaterally remove all trees, and would have unexpected
-            /// side effects. This opts those out of operating on ones with generated documents where there would be side effects.
-            /// </remarks>
-            public abstract bool CanUpdateCompilationWithStaleGeneratedTreesIfGeneratorsGiveSameOutput { get; }
+        /// <remarks>
+        /// Most translation actions add or remove a single syntax tree which means we can do the "same" change
+        /// to a compilation that contains the generated files and one that doesn't; however some translation actions
+        /// (like <see cref="ReplaceAllSyntaxTreesAction"/>) will unilaterally remove all trees, and would have unexpected
+        /// side effects. This opts those out of operating on ones with generated documents where there would be side effects.
+        /// </remarks>
+        public abstract bool CanUpdateCompilationWithStaleGeneratedTreesIfGeneratorsGiveSameOutput { get; }
 
-            public abstract GeneratorDriver TransformGeneratorDriver(GeneratorDriver generatorDriver);
+        public abstract GeneratorDriver TransformGeneratorDriver(GeneratorDriver generatorDriver);
 
-            /// <summary>
-            /// When changes are made to a solution, we make a list of translation actions. If multiple similar changes happen in rapid
-            /// succession, we may be able to merge them without holding onto intermediate state.
-            /// </summary>
-            /// <param name="priorAction">The action prior to this one. May be a different type.</param>
-            /// <returns>A non-null <see cref="CompilationAndGeneratorDriverTranslationAction" /> if we could create a merged one, null otherwise.</returns>
-            public virtual CompilationAndGeneratorDriverTranslationAction? TryMergeWithPrior(CompilationAndGeneratorDriverTranslationAction priorAction)
-                => null;
-        }
+        /// <summary>
+        /// When changes are made to a solution, we make a list of translation actions. If multiple similar changes happen in rapid
+        /// succession, we may be able to merge them without holding onto intermediate state.
+        /// </summary>
+        /// <param name="priorAction">The action prior to this one. May be a different type.</param>
+        /// <returns>A non-null <see cref="CompilationAndGeneratorDriverTranslationAction" /> if we could create a merged one, null otherwise.</returns>
+        public virtual CompilationAndGeneratorDriverTranslationAction? TryMergeWithPrior(CompilationAndGeneratorDriverTranslationAction priorAction)
+            => null;
     }
 }

src/Workspaces/Core/Portable/Workspace/Solution/SolutionCompilationState.CompilationAndGeneratorDriverTranslationAction_Actions.cs

@@ -55,10 +55,13 @@ internal sealed class TouchAdditionalDocumentAction(AdditionalDocumentState oldS
                 private readonly AdditionalDocumentState _newState = newState;
 
                 // Changing an additional document doesn't change the compilation directly, so we can "apply" the
-                // translation (which is a no-op). Since we use a 'false' here to mean that it's not worth keeping
-                // the compilation with stale trees around, answering true is still important.
+                // translation (which is a no-op). Since we use a 'false' here to mean that it's not worth keeping the
+                // compilation with stale trees around, answering true is still important.
                 public override bool CanUpdateCompilationWithStaleGeneratedTreesIfGeneratorsGiveSameOutput => true;
 
+                public override Task<Compilation> TransformCompilationAsync(Compilation oldCompilation, CancellationToken cancellationToken)
+                    => Task.FromResult(oldCompilation);
+
                 public override CompilationAndGeneratorDriverTranslationAction? TryMergeWithPrior(CompilationAndGeneratorDriverTranslationAction priorAction)
                 {
                     if (priorAction is TouchAdditionalDocumentAction priorTouchAction &&
@@ -198,12 +201,14 @@ public override GeneratorDriver TransformGeneratorDriver(GeneratorDriver generat
 
             internal sealed class AddOrRemoveAnalyzerReferencesAction(string language, ImmutableArray<AnalyzerReference> referencesToAdd = default, ImmutableArray<AnalyzerReference> referencesToRemove = default) : CompilationAndGeneratorDriverTranslationAction
             {
-
                 // Changing analyzer references doesn't change the compilation directly, so we can "apply" the
-                // translation (which is a no-op). Since we use a 'false' here to mean that it's not worth keeping
-                // the compilation with stale trees around, answering true is still important.
+                // translation (which is a no-op). Since we use a 'false' here to mean that it's not worth keeping the
+                // compilation with stale trees around, answering true is still important.
                 public override bool CanUpdateCompilationWithStaleGeneratedTreesIfGeneratorsGiveSameOutput => true;
 
+                public override Task<Compilation> TransformCompilationAsync(Compilation oldCompilation, CancellationToken cancellationToken)
+                    => Task.FromResult(oldCompilation);
+
                 public override GeneratorDriver TransformGeneratorDriver(GeneratorDriver generatorDriver)
                 {
                     if (!referencesToRemove.IsDefaultOrEmpty)
@@ -222,12 +227,14 @@ public override GeneratorDriver TransformGeneratorDriver(GeneratorDriver generat
 
             internal sealed class AddAdditionalDocumentsAction(ImmutableArray<AdditionalDocumentState> additionalDocuments) : CompilationAndGeneratorDriverTranslationAction
             {
-
                 // Changing an additional document doesn't change the compilation directly, so we can "apply" the
-                // translation (which is a no-op). Since we use a 'false' here to mean that it's not worth keeping
-                // the compilation with stale trees around, answering true is still important.
+                // translation (which is a no-op). Since we use a 'false' here to mean that it's not worth keeping the
+                // compilation with stale trees around, answering true is still important.
                 public override bool CanUpdateCompilationWithStaleGeneratedTreesIfGeneratorsGiveSameOutput => true;
 
+                public override Task<Compilation> TransformCompilationAsync(Compilation oldCompilation, CancellationToken cancellationToken)
+                    => Task.FromResult(oldCompilation);
+
                 public override GeneratorDriver TransformGeneratorDriver(GeneratorDriver generatorDriver)
                 {
                     return generatorDriver.AddAdditionalTexts(additionalDocuments.SelectAsArray(static documentState => documentState.AdditionalText));
@@ -236,12 +243,14 @@ public override GeneratorDriver TransformGeneratorDriver(GeneratorDriver generat
 
             internal sealed class RemoveAdditionalDocumentsAction(ImmutableArray<AdditionalDocumentState> additionalDocuments) : CompilationAndGeneratorDriverTranslationAction
             {
-
                 // Changing an additional document doesn't change the compilation directly, so we can "apply" the
-                // translation (which is a no-op). Since we use a 'false' here to mean that it's not worth keeping
-                // the compilation with stale trees around, answering true is still important.
+                // translation (which is a no-op). Since we use a 'false' here to mean that it's not worth keeping the
+                // compilation with stale trees around, answering true is still important.
                 public override bool CanUpdateCompilationWithStaleGeneratedTreesIfGeneratorsGiveSameOutput => true;
 
+                public override Task<Compilation> TransformCompilationAsync(Compilation oldCompilation, CancellationToken cancellationToken)
+                    => Task.FromResult(oldCompilation);
+
                 public override GeneratorDriver TransformGeneratorDriver(GeneratorDriver generatorDriver)
                 {
                     return generatorDriver.RemoveAdditionalTexts(additionalDocuments.SelectAsArray(static documentState => documentState.AdditionalText));
@@ -252,6 +261,11 @@ internal sealed class ReplaceGeneratorDriverAction(GeneratorDriver oldGeneratorD
             {
                 public override bool CanUpdateCompilationWithStaleGeneratedTreesIfGeneratorsGiveSameOutput => true;
 
+                // Replacing the generator doesn't change the non-generator compilation.  So we can just return the old
+                // compilation as is.
+                public override Task<Compilation> TransformCompilationAsync(Compilation oldCompilation, CancellationToken cancellationToken)
+                    => Task.FromResult(oldCompilation);
+
                 public override GeneratorDriver TransformGeneratorDriver(GeneratorDriver _)
                 {
                     // The GeneratorDriver that we have here is from a prior version of the Project, it may be missing state changes due