Let the helper also return whether there's any disallowed change

So the comsumer can use that to provide additional info to users. e.g. display a warning.

src/EditorFeatures/Core.Wpf/InlineRename/InlineRenameSession.cs

@@ -691,7 +691,7 @@ private void CommitCore(IWaitContext waitContext, bool previewChanges)
 
                 var excludeChangesTask = newSolution.ExcludeDisallowedDocumentTextChangesAsync(_workspace.CurrentSolution, waitContext.CancellationToken);
                 excludeChangesTask.Wait(waitContext.CancellationToken);
-                newSolution = excludeChangesTask.Result;
+                newSolution = excludeChangesTask.Result.purgedSolution;
 
                 waitContext.AllowCancel = false;
 

src/Features/Core/Portable/ChangeSignature/AbstractChangeSignatureService.cs

@@ -360,7 +360,8 @@ internal async Task<ChangeSignatureResult> ChangeSignatureWithContextAsync(Chang
                 updatedSolution = updatedSolution.WithDocumentSyntaxRoot(docId, updatedRoots[docId]);
             }
 
-            return await updatedSolution.ExcludeDisallowedDocumentTextChangesAsync(originalSolution, cancellationToken).ConfigureAwait(false);
+            (_, updatedSolution) = await updatedSolution.ExcludeDisallowedDocumentTextChangesAsync(originalSolution, cancellationToken).ConfigureAwait(false);
+            return updatedSolution;
         }
 
 #nullable restore

src/Features/Core/Portable/CodeRefactorings/SyncNamespace/AbstractChangeNamespaceService.cs

@@ -189,8 +189,9 @@ await ChangeNamespaceInSingleDocumentAsync(solutionAfterNamespaceChange, documen
                     cancellationToken).ConfigureAwait(false);
 
                 var mergedSolution = await MergeDiffAsync(solutionAfterFirstMerge, solutionAfterImportsRemoved, cancellationToken).ConfigureAwait(false);
+                (_, mergedSolution) = await mergedSolution.ExcludeDisallowedDocumentTextChangesAsync(solution, cancellationToken).ConfigureAwait(false);
 
-                return await mergedSolution.ExcludeDisallowedDocumentTextChangesAsync(solution, cancellationToken).ConfigureAwait(false);
+                return mergedSolution;
             }
             finally
             {

src/Workspaces/Core/Portable/Shared/Extensions/ISolutionExtensions.cs

@@ -90,9 +90,10 @@ public static IEnumerable<DocumentId> FilterDocumentIdsByLanguage(this Solution
             }
         }
 
-        public static async Task<Solution> ExcludeDisallowedDocumentTextChangesAsync(this Solution newSolution, Solution oldSolution, CancellationToken cancellationToken)
+        public static async Task<(bool containsDisallowedChange, Solution purgedSolution)> ExcludeDisallowedDocumentTextChangesAsync(this Solution newSolution, Solution oldSolution, CancellationToken cancellationToken)
         {
             var solutionChanges = newSolution.GetChanges(oldSolution);
+            var containsDisallowedChange = false;
 
             foreach (var projectChange in solutionChanges.GetProjectChanges())
             {
@@ -104,6 +105,8 @@ public static async Task<Solution> ExcludeDisallowedDocumentTextChangesAsync(thi
                         continue;
                     }
 
+                    containsDisallowedChange = true;
+
                     var oldRoot = await oldDocument.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
                     var newDocument = newSolution.GetDocument(changedDocumentId)!;
                     var revertedDocument = newDocument.WithSyntaxRoot(oldRoot);
@@ -112,7 +115,7 @@ public static async Task<Solution> ExcludeDisallowedDocumentTextChangesAsync(thi
                 }
             }
 
-            return newSolution;
+            return (containsDisallowedChange, newSolution);
         }
     }
 }