Proved a diagnostics for prebuilt stubs in case of stub/AST mismatch

platform/core-impl/src/com/intellij/psi/stubs/CoreStubTreeLoader.java

@@ -28,6 +28,7 @@ import com.intellij.psi.tree.IStubFileElementType;
 import com.intellij.util.indexing.FileContent;
 import com.intellij.util.indexing.FileContentImpl;
 import com.intellij.util.indexing.IndexingDataKeys;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.io.IOException;
@@ -83,4 +84,8 @@ public class CoreStubTreeLoader extends StubTreeLoader {
     return false;
   }
 
+  @Override
+  protected boolean isPrebuilt(@NotNull VirtualFile virtualFile) {
+    return false;
+  }
 }

platform/core-impl/src/com/intellij/psi/stubs/StubTreeLoader.java

@@ -77,7 +77,14 @@ public abstract class StubTreeLoader {
     IndexingStampInfo indexingStampInfo = getIndexingStampInfo(file);
     boolean upToDate = indexingStampInfo != null && indexingStampInfo.isUpToDate(document, file, psiFile);
 
+    boolean canBePrebuilt = isPrebuilt(psiFile.getVirtualFile());
+
     String msg = _message + "\nPlease report the problem to JetBrains with the files attached\n";
+
+    if (canBePrebuilt) {
+      msg += "This stub can have pre-built origin\n";
+    }
+
     if (upToDate) {
       msg += "INDEXED VERSION IS THE CURRENT ONE";
     }
@@ -136,6 +143,8 @@ public abstract class StubTreeLoader {
     return upToDate ? handleUpToDateMismatch(msg, attachments) : new RuntimeExceptionWithAttachments(msg, attachments);
   }
 
+  protected abstract boolean isPrebuilt(@NotNull VirtualFile virtualFile);
+
   private static UpToDateStubIndexMismatch handleUpToDateMismatch(@NotNull String message, Attachment[] attachments) {
     return new UpToDateStubIndexMismatch(message, attachments);
   }

platform/lang-impl/src/com/intellij/psi/stubs/StubTreeLoaderImpl.java

@@ -247,4 +247,22 @@ public class StubTreeLoaderImpl extends StubTreeLoader {
   protected IndexingStampInfo getIndexingStampInfo(@NotNull VirtualFile file) {
     return StubUpdatingIndex.getIndexingStampInfo(file);
   }
+
+  @Override
+  protected boolean isPrebuilt(@NotNull VirtualFile virtualFile) {
+      boolean canBePrebuilt = false;
+      try {
+        final PrebuiltStubsProvider prebuiltStubsProvider =
+          PrebuiltStubsProviders.INSTANCE.forFileType(virtualFile.getFileType());
+        if (prebuiltStubsProvider != null) {
+          canBePrebuilt = null !=
+                          prebuiltStubsProvider
+                            .findStub(new FileContentImpl(virtualFile, virtualFile.contentsToByteArray()));
+        }
+      }
+      catch (Exception e) {
+        // pass
+      }
+      return canBePrebuilt;
+    }
 }