[lldb] Use forward decls with redeclared definitions instead of minimal import for records

clang/include/clang/AST/ASTImporter.h

@@ -211,6 +211,7 @@ class TypeSourceInfo;
 
     /// Whether to perform a minimal import.
     bool Minimal;
+    bool LLDBRedeclCompletion = false;
 
     ODRHandlingType ODRHandling;
 
@@ -296,8 +297,10 @@ class TypeSourceInfo;
     /// Whether the importer will perform a minimal import, creating
     /// to-be-completed forward declarations when possible.
     bool isMinimalImport() const { return Minimal; }
+    bool hasLLDBRedeclCompletion() const { return LLDBRedeclCompletion; }
 
     void setODRHandling(ODRHandlingType T) { ODRHandling = T; }
+    void setLLDBRedeclCompletion(bool Val) { LLDBRedeclCompletion = Val; }
 
     /// \brief Import the given object, returns the result.
     ///

clang/include/clang/AST/DeclObjC.h

@@ -1238,7 +1238,8 @@ class ObjCInterfaceDecl : public ObjCContainerDecl
   /// which will be NULL if this class has not yet been defined.
   ///
   /// The bit indicates when we don't need to check for out-of-date
-  /// declarations. It will be set unless modules are enabled.
+  /// declarations. It will be set unless there is an ExternalASTSource that
+  /// could provide a definition.
   llvm::PointerIntPair<DefinitionData *, 1, bool> Data;
 
   ObjCInterfaceDecl(const ASTContext &C, DeclContext *DC, SourceLocation AtLoc,
@@ -1527,7 +1528,7 @@ class ObjCInterfaceDecl : public ObjCContainerDecl
     // If the name of this class is out-of-date, bring it up-to-date, which
     // might bring in a definition.
     // Note: a null value indicates that we don't have a definition and that
-    // modules are enabled.
+    // there is a ExternalASTSource that could provide a definition.
     if (!Data.getOpaqueValue())
       getMostRecentDecl();
 
@@ -2095,7 +2096,8 @@ class ObjCProtocolDecl : public ObjCContainerDecl,
   /// which will be NULL if this class has not yet been defined.
   ///
   /// The bit indicates when we don't need to check for out-of-date
-  /// declarations. It will be set unless modules are enabled.
+  /// declarations. It will be set unless there is an ExternalASTSource that
+  /// could provide a definition.
   llvm::PointerIntPair<DefinitionData *, 1, bool> Data;
 
   ObjCProtocolDecl(ASTContext &C, DeclContext *DC, IdentifierInfo *Id,
@@ -2232,7 +2234,7 @@ class ObjCProtocolDecl : public ObjCContainerDecl,
     // If the name of this protocol is out-of-date, bring it up-to-date, which
     // might bring in a definition.
     // Note: a null value indicates that we don't have a definition and that
-    // modules are enabled.
+    // there is a ExternalASTSource that could provide a definition.
     if (!Data.getOpaqueValue())
       getMostRecentDecl();
 

clang/lib/AST/ASTImporter.cpp

@@ -1031,7 +1031,8 @@ Expected<LambdaCapture> ASTNodeImporter::import(const LambdaCapture &From) {
 
 template <typename T>
 bool ASTNodeImporter::hasSameVisibilityContextAndLinkage(T *Found, T *From) {
-  if (Found->getLinkageInternal() != From->getLinkageInternal())
+  if (!Importer.hasLLDBRedeclCompletion() &&
+      Found->getLinkageInternal() != From->getLinkageInternal())
     return false;
 
   if (From->hasExternalFormalLinkage())
@@ -1482,7 +1483,9 @@ ExpectedType ASTNodeImporter::VisitInjectedClassNameType(
 }
 
 ExpectedType ASTNodeImporter::VisitRecordType(const RecordType *T) {
+  // getCanonicalDecl in order to not trigger redeclaration completion
   Expected<RecordDecl *> ToDeclOrErr = import(T->getDecl());
+
   if (!ToDeclOrErr)
     return ToDeclOrErr.takeError();
 
@@ -1771,8 +1774,9 @@ Error ASTNodeImporter::ImportDefinitionIfNeeded(Decl *FromD, Decl *ToD) {
 
   if (RecordDecl *FromRecord = dyn_cast<RecordDecl>(FromD)) {
     if (RecordDecl *ToRecord = cast<RecordDecl>(ToD)) {
-      if (FromRecord->getDefinition() && FromRecord->isCompleteDefinition() &&
-          !ToRecord->getDefinition()) {
+      if (FromRecord->getDefinition() && !ToRecord->getDefinition() &&
+          (Importer.hasLLDBRedeclCompletion() ||
+           FromRecord->isCompleteDefinition())) {
         if (Error Err = ImportDefinition(FromRecord, ToRecord))
           return Err;
       }
@@ -1873,12 +1877,15 @@ ASTNodeImporter::ImportDeclContext(DeclContext *FromDC, bool ForceImport) {
                                                 ImportedOrErr.takeError());
       continue;
     }
-    FieldDecl *FieldFrom = dyn_cast_or_null<FieldDecl>(From);
-    Decl *ImportedDecl = *ImportedOrErr;
-    FieldDecl *FieldTo = dyn_cast_or_null<FieldDecl>(ImportedDecl);
-    if (FieldFrom && FieldTo) {
-      Error Err = ImportFieldDeclDefinition(FieldFrom, FieldTo);
-      HandleChildErrors.handleChildImportResult(ChildErrors, std::move(Err));
+
+    if (Importer.hasLLDBRedeclCompletion()) {
+      FieldDecl *FieldFrom = dyn_cast_or_null<FieldDecl>(From);
+      Decl *ImportedDecl = *ImportedOrErr;
+      FieldDecl *FieldTo = dyn_cast_or_null<FieldDecl>(ImportedDecl);
+      if (FieldFrom && FieldTo) {
+        Error Err = ImportFieldDeclDefinition(FieldFrom, FieldTo);
+        HandleChildErrors.handleChildImportResult(ChildErrors, std::move(Err));
+      }
     }
   }
 
@@ -2039,7 +2046,11 @@ Error ASTNodeImporter::ImportDefinition(
     To->completeDefinition();
   };
 
-  if (To->getDefinition() || To->isBeingDefined()) {
+  bool hasDef = (Importer.hasLLDBRedeclCompletion() &&
+                 To->isThisDeclarationADefinition()) ||
+                To->getDefinition();
+
+  if (hasDef || To->isBeingDefined()) {
     if (Kind == IDK_Everything ||
         // In case of lambdas, the class already has a definition ptr set, but
         // the contained decls are not imported yet. Also, isBeingDefined was
@@ -2558,6 +2569,9 @@ ASTNodeImporter::VisitTypedefNameDecl(TypedefNameDecl *D, bool IsAlias) {
                 !hasSameVisibilityContextAndLinkage(FoundR, FromR))
               continue;
           }
+
+          if (Importer.hasLLDBRedeclCompletion() && Importer.isMinimalImport())
+            return Importer.MapImported(D, FoundTypedef);
           // If the "From" context has a complete underlying type but we
           // already have a complete underlying type then return with that.
           if (!FromUT->isIncompleteType() && !FoundUT->isIncompleteType())
@@ -2822,9 +2836,11 @@ ExpectedDecl ASTNodeImporter::VisitEnumDecl(EnumDecl *D) {
       return POIOrErr.takeError();
   }
 
+  auto Kind = Importer.hasLLDBRedeclCompletion() ? IDK_Everything : IDK_Default;
+
   // Import the definition
   if (D->isCompleteDefinition())
-    if (Error Err = ImportDefinition(D, D2))
+    if (Error Err = ImportDefinition(D, D2, Kind))
       return std::move(Err);
 
   return D2;
@@ -2902,7 +2918,8 @@ ExpectedDecl ASTNodeImporter::VisitRecordDecl(RecordDecl *D) {
 
         if (IsStructuralMatch(D, FoundRecord)) {
           RecordDecl *FoundDef = FoundRecord->getDefinition();
-          if (D->isThisDeclarationADefinition() && FoundDef) {
+          if (!Importer.hasLLDBRedeclCompletion() &&
+              D->isThisDeclarationADefinition() && FoundDef) {
             // FIXME: Structural equivalence check should check for same
             // user-defined methods.
             Importer.MapImported(D, FoundDef);
@@ -3078,8 +3095,9 @@ ExpectedDecl ASTNodeImporter::VisitRecordDecl(RecordDecl *D) {
   if (D->isAnonymousStructOrUnion())
     D2->setAnonymousStructOrUnion(true);
 
+  auto Kind = Importer.hasLLDBRedeclCompletion() ? IDK_Everything : IDK_Default;
   if (D->isCompleteDefinition())
-    if (Error Err = ImportDefinition(D, D2, IDK_Default))
+    if (Error Err = ImportDefinition(D, D2, Kind))
       return std::move(Err);
 
   return D2;
@@ -5203,7 +5221,8 @@ Error ASTNodeImporter::ImportDefinition(
                           diag::note_odr_objc_missing_superclass);
     }
 
-    if (shouldForceImportDeclContext(Kind))
+    if (Importer.hasLLDBRedeclCompletion() ||
+        shouldForceImportDeclContext(Kind))
       if (Error Err = ImportDeclContext(From))
         return Err;
     return Error::success();
@@ -6084,8 +6103,9 @@ ExpectedDecl ASTNodeImporter::VisitClassTemplateSpecializationDecl(
     }
   }
 
+  auto Kind = Importer.hasLLDBRedeclCompletion() ? IDK_Everything : IDK_Default;
   if (D->isCompleteDefinition())
-    if (Error Err = ImportDefinition(D, D2))
+    if (Error Err = ImportDefinition(D, D2, Kind))
       return std::move(Err);
 
   return D2;

clang/lib/AST/DeclObjC.cpp

@@ -1546,7 +1546,7 @@ ObjCInterfaceDecl *ObjCInterfaceDecl::Create(const ASTContext &C,
   auto *Result = new (C, DC)
       ObjCInterfaceDecl(C, DC, atLoc, Id, typeParamList, ClassLoc, PrevDecl,
                         isInternal);
-  Result->Data.setInt(!C.getLangOpts().Modules);
+  Result->Data.setInt(!C.getExternalSource());
   C.getObjCInterfaceType(Result, PrevDecl);
   return Result;
 }
@@ -1556,7 +1556,7 @@ ObjCInterfaceDecl *ObjCInterfaceDecl::CreateDeserialized(const ASTContext &C,
   auto *Result = new (C, ID)
       ObjCInterfaceDecl(C, nullptr, SourceLocation(), nullptr, nullptr,
                         SourceLocation(), nullptr, false);
-  Result->Data.setInt(!C.getLangOpts().Modules);
+  Result->Data.setInt(!C.getExternalSource());
   return Result;
 }
 
@@ -1947,7 +1947,7 @@ ObjCProtocolDecl *ObjCProtocolDecl::Create(ASTContext &C, DeclContext *DC,
                                            ObjCProtocolDecl *PrevDecl) {
   auto *Result =
       new (C, DC) ObjCProtocolDecl(C, DC, Id, nameLoc, atStartLoc, PrevDecl);
-  Result->Data.setInt(!C.getLangOpts().Modules);
+  Result->Data.setInt(!C.getExternalSource());
   return Result;
 }
 
@@ -1956,7 +1956,7 @@ ObjCProtocolDecl *ObjCProtocolDecl::CreateDeserialized(ASTContext &C,
   ObjCProtocolDecl *Result =
       new (C, ID) ObjCProtocolDecl(C, nullptr, nullptr, SourceLocation(),
                                    SourceLocation(), nullptr);
-  Result->Data.setInt(!C.getLangOpts().Modules);
+  Result->Data.setInt(!C.getExternalSource());
   return Result;
 }
 

lldb/include/lldb/Core/PluginManager.h

@@ -474,6 +474,7 @@ class PluginManager {
   // TypeSystem
   static bool RegisterPlugin(llvm::StringRef name, llvm::StringRef description,
                              TypeSystemCreateInstance create_callback,
+                             DebuggerInitializeCallback debugger_callback,
                              LanguageSet supported_languages_for_types,
                              LanguageSet supported_languages_for_expressions);
 
@@ -528,6 +529,13 @@ class PluginManager {
       Debugger &debugger, const lldb::OptionValuePropertiesSP &properties_sp,
       llvm::StringRef description, bool is_global_property);
 
+  static lldb::OptionValuePropertiesSP
+  GetSettingForTypeSystemPlugin(Debugger &debugger, ConstString setting_name);
+
+  static bool CreateSettingForTypeSystemPlugin(
+      Debugger &debugger, const lldb::OptionValuePropertiesSP &properties_sp,
+      ConstString description, bool is_global_property);
+
   static bool CreateSettingForTracePlugin(
       Debugger &debugger, const lldb::OptionValuePropertiesSP &properties_sp,
       llvm::StringRef description, bool is_global_property);

lldb/source/Core/PluginManager.cpp

@@ -1423,10 +1423,11 @@ PluginManager::GetInstrumentationRuntimeCreateCallbackAtIndex(uint32_t idx) {
 struct TypeSystemInstance : public PluginInstance<TypeSystemCreateInstance> {
   TypeSystemInstance(llvm::StringRef name, llvm::StringRef description,
                      CallbackType create_callback,
+                     DebuggerInitializeCallback debugger_init_callback,
                      LanguageSet supported_languages_for_types,
                      LanguageSet supported_languages_for_expressions)
-      : PluginInstance<TypeSystemCreateInstance>(name, description,
-                                                 create_callback),
+      : PluginInstance<TypeSystemCreateInstance>(
+            name, description, create_callback, debugger_init_callback),
         supported_languages_for_types(supported_languages_for_types),
         supported_languages_for_expressions(
             supported_languages_for_expressions) {}
@@ -1445,11 +1446,12 @@ static TypeSystemInstances &GetTypeSystemInstances() {
 bool PluginManager::RegisterPlugin(
     llvm::StringRef name, llvm::StringRef description,
     TypeSystemCreateInstance create_callback,
+    DebuggerInitializeCallback debugger_init_callback,
     LanguageSet supported_languages_for_types,
     LanguageSet supported_languages_for_expressions) {
   return GetTypeSystemInstances().RegisterPlugin(
-      name, description, create_callback, supported_languages_for_types,
-      supported_languages_for_expressions);
+      name, description, create_callback, debugger_init_callback,
+      supported_languages_for_types, supported_languages_for_expressions);
 }
 
 bool PluginManager::UnregisterPlugin(TypeSystemCreateInstance create_callback) {
@@ -1536,6 +1538,7 @@ void PluginManager::DebuggerInitialize(Debugger &debugger) {
   GetOperatingSystemInstances().PerformDebuggerCallback(debugger);
   GetStructuredDataPluginInstances().PerformDebuggerCallback(debugger);
   GetTracePluginInstances().PerformDebuggerCallback(debugger);
+  GetTypeSystemInstances().PerformDebuggerCallback(debugger);
 }
 
 // This is the preferred new way to register plugin specific settings.  e.g.
@@ -1660,6 +1663,7 @@ static constexpr llvm::StringLiteral kProcessPluginName("process");
 static constexpr llvm::StringLiteral kTracePluginName("trace");
 static constexpr llvm::StringLiteral kObjectFilePluginName("object-file");
 static constexpr llvm::StringLiteral kSymbolFilePluginName("symbol-file");
+static constexpr llvm::StringLiteral kTypeSystemPluginName("typesystem");
 static constexpr llvm::StringLiteral kJITLoaderPluginName("jit-loader");
 static constexpr llvm::StringLiteral
     kStructuredDataPluginName("structured-data");
@@ -1744,6 +1748,22 @@ bool PluginManager::CreateSettingForSymbolFilePlugin(
                                 properties_sp, description, is_global_property);
 }
 
+lldb::OptionValuePropertiesSP
+PluginManager::GetSettingForTypeSystemPlugin(Debugger &debugger,
+                                             ConstString setting_name) {
+  return GetSettingForPlugin(debugger, setting_name,
+                             ConstString(kTypeSystemPluginName));
+}
+
+bool PluginManager::CreateSettingForTypeSystemPlugin(
+    Debugger &debugger, const lldb::OptionValuePropertiesSP &properties_sp,
+    ConstString description, bool is_global_property) {
+  return CreateSettingForPlugin(
+      debugger, ConstString(kTypeSystemPluginName),
+      ConstString("Settings for type system plug-ins"), properties_sp,
+      description, is_global_property);
+}
+
 lldb::OptionValuePropertiesSP
 PluginManager::GetSettingForJITLoaderPlugin(Debugger &debugger,
                                             llvm::StringRef setting_name) {

lldb/source/Plugins/ExpressionParser/Clang/ASTUtils.h

@@ -9,6 +9,7 @@
 #ifndef LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_ASTUTILS_H
 #define LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_ASTUTILS_H
 
+#include "Plugins/TypeSystem/Clang/ImporterBackedASTSource.h"
 #include "clang/Basic/Module.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/MultiplexExternalSemaSource.h"
@@ -20,7 +21,7 @@ namespace lldb_private {
 
 /// Wraps an ExternalASTSource into an ExternalSemaSource. Doesn't take
 /// ownership of the provided source.
-class ExternalASTSourceWrapper : public clang::ExternalSemaSource {
+class ExternalASTSourceWrapper : public ImporterBackedASTSource {
   ExternalASTSource *m_Source;
 
 public:
@@ -240,7 +241,7 @@ class ASTConsumerForwarder : public clang::SemaConsumer {
 /// provide more accurate replies to the requests, but might not be able to
 /// answer all requests. The debug information will be used as a fallback then
 /// to provide information that is not in the C++ module.
-class SemaSourceWithPriorities : public clang::ExternalSemaSource {
+class SemaSourceWithPriorities : public ImporterBackedASTSource {
 
 private:
   /// The sources ordered in decreasing priority.
@@ -273,9 +274,16 @@ class SemaSourceWithPriorities : public clang::ExternalSemaSource {
     return nullptr;
   }
 
+  /// Call ExternalASTSource::CompleteRedeclChain(D)
+  /// on each AST source. Returns as soon as we got
+  /// a definition for D.
   void CompleteRedeclChain(const clang::Decl *D) override {
-    for (size_t i = 0; i < Sources.size(); ++i)
+    for (size_t i = 0; i < Sources.size(); ++i) {
       Sources[i]->CompleteRedeclChain(D);
+      if (auto *td = llvm::dyn_cast<clang::TagDecl>(D))
+        if (td->getDefinition())
+          return;
+    }
   }
 
   clang::Selector GetExternalSelector(uint32_t ID) override {