PR29097: add an update record when we instantiate the default member

initializer of an imported field.

llvm-svn: 279667

Author: zygoloid

clang/include/clang/AST/ASTMutationListener.h

@@ -22,6 +22,7 @@ namespace clang {
   class CXXRecordDecl;
   class Decl;
   class DeclContext;
+  class FieldDecl;
   class FunctionDecl;
   class FunctionTemplateDecl;
   class Module;
@@ -93,6 +94,9 @@ class ASTMutationListener {
   /// \brief A default argument was instantiated.
   virtual void DefaultArgumentInstantiated(const ParmVarDecl *D) {}
 
+  /// \brief A default member initializer was instantiated.
+  virtual void DefaultMemberInitializerInstantiated(const FieldDecl *D) {}
+
   /// \brief A new objc category class was added for an interface.
   virtual void AddedObjCCategoryToInterface(const ObjCCategoryDecl *CatD,
                                             const ObjCInterfaceDecl *IFD) {}

clang/include/clang/Serialization/ASTWriter.h

@@ -674,6 +674,7 @@ class ASTWriter : public ASTDeserializationListener,
   void CompletedImplicitDefinition(const FunctionDecl *D) override;
   void StaticDataMemberInstantiated(const VarDecl *D) override;
   void DefaultArgumentInstantiated(const ParmVarDecl *D) override;
+  void DefaultMemberInitializerInstantiated(const FieldDecl *D) override;
   void FunctionDefinitionInstantiated(const FunctionDecl *D) override;
   void AddedObjCCategoryToInterface(const ObjCCategoryDecl *CatD,
                                     const ObjCInterfaceDecl *IFD) override;

clang/lib/Frontend/MultiplexConsumer.cpp

@@ -120,6 +120,7 @@ class MultiplexASTMutationListener : public ASTMutationListener {
   void CompletedImplicitDefinition(const FunctionDecl *D) override;
   void StaticDataMemberInstantiated(const VarDecl *D) override;
   void DefaultArgumentInstantiated(const ParmVarDecl *D) override;
+  void DefaultMemberInitializerInstantiated(const FieldDecl *D) override;
   void AddedObjCCategoryToInterface(const ObjCCategoryDecl *CatD,
                                     const ObjCInterfaceDecl *IFD) override;
   void FunctionDefinitionInstantiated(const FunctionDecl *D) override;
@@ -201,6 +202,11 @@ void MultiplexASTMutationListener::DefaultArgumentInstantiated(
   for (size_t i = 0, e = Listeners.size(); i != e; ++i)
     Listeners[i]->DefaultArgumentInstantiated(D);
 }
+void MultiplexASTMutationListener::DefaultMemberInitializerInstantiated(
+                                                           const FieldDecl *D) {
+  for (size_t i = 0, e = Listeners.size(); i != e; ++i)
+    Listeners[i]->DefaultMemberInitializerInstantiated(D);
+}
 void MultiplexASTMutationListener::AddedObjCCategoryToInterface(
                                                  const ObjCCategoryDecl *CatD,
                                                  const ObjCInterfaceDecl *IFD) {

clang/lib/Sema/SemaTemplateInstantiate.cpp

@@ -15,6 +15,7 @@
 #include "clang/AST/ASTConsumer.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/ASTLambda.h"
+#include "clang/AST/ASTMutationListener.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/Expr.h"
 #include "clang/Basic/LangOptions.h"
@@ -2215,6 +2216,9 @@ bool Sema::InstantiateInClassInitializer(
   ActOnFinishCXXInClassMemberInitializer(
       Instantiation, Init ? Init->getLocStart() : SourceLocation(), Init);
 
+  if (auto *L = getASTMutationListener())
+    L->DefaultMemberInitializerInstantiated(Instantiation);
+
   // Exit the scope of this instantiation.
   SavedContext.pop();
 

clang/lib/Serialization/ASTCommon.h

@@ -30,6 +30,7 @@ enum DeclUpdateKind {
   UPD_CXX_INSTANTIATED_STATIC_DATA_MEMBER,
   UPD_CXX_INSTANTIATED_CLASS_DEFINITION,
   UPD_CXX_INSTANTIATED_DEFAULT_ARGUMENT,
+  UPD_CXX_INSTANTIATED_DEFAULT_MEMBER_INITIALIZER,
   UPD_CXX_RESOLVED_DTOR_DELETE,
   UPD_CXX_RESOLVED_EXCEPTION_SPEC,
   UPD_CXX_DEDUCED_RETURN_TYPE,

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -3796,6 +3796,23 @@ void ASTDeclReader::UpdateDecl(Decl *D, ModuleFile &ModuleFile,
       break;
     }
 
+    case UPD_CXX_INSTANTIATED_DEFAULT_MEMBER_INITIALIZER: {
+      auto FD = cast<FieldDecl>(D);
+      auto DefaultInit = Reader.ReadExpr(F);
+
+      // Only apply the update if the field still has an uninstantiated
+      // default member initializer.
+      if (FD->hasInClassInitializer() && !FD->getInClassInitializer()) {
+        if (DefaultInit)
+          FD->setInClassInitializer(DefaultInit);
+        else
+          // Instantiation failed. We can get here if we serialized an AST for
+          // an invalid program.
+          FD->removeInClassInitializer();
+      }
+      break;
+    }
+
     case UPD_CXX_ADDED_FUNCTION_DEFINITION: {
       FunctionDecl *FD = cast<FunctionDecl>(D);
       if (Reader.PendingBodies[FD]) {

clang/lib/Serialization/ASTWriter.cpp

@@ -4702,6 +4702,11 @@ void ASTWriter::WriteDeclUpdatesBlocks(RecordDataImpl &OffsetsRecord) {
             cast<ParmVarDecl>(Update.getDecl())->getDefaultArg()));
         break;
 
+      case UPD_CXX_INSTANTIATED_DEFAULT_MEMBER_INITIALIZER:
+        Record.AddStmt(
+            cast<FieldDecl>(Update.getDecl())->getInClassInitializer());
+        break;
+
       case UPD_CXX_INSTANTIATED_CLASS_DEFINITION: {
         auto *RD = cast<CXXRecordDecl>(D);
         UpdatedDeclContexts.insert(RD->getPrimaryContext());
@@ -5815,6 +5820,15 @@ void ASTWriter::DefaultArgumentInstantiated(const ParmVarDecl *D) {
       DeclUpdate(UPD_CXX_INSTANTIATED_DEFAULT_ARGUMENT, D));
 }
 
+void ASTWriter::DefaultMemberInitializerInstantiated(const FieldDecl *D) {
+  assert(!WritingAST && "Already writing the AST!");
+  if (!D->isFromASTFile())
+    return;
+
+  DeclUpdates[D].push_back(
+      DeclUpdate(UPD_CXX_INSTANTIATED_DEFAULT_MEMBER_INITIALIZER, D));
+}
+
 void ASTWriter::AddedObjCCategoryToInterface(const ObjCCategoryDecl *CatD,
                                              const ObjCInterfaceDecl *IFD) {
   if (Chain && Chain->isProcessingUpdateRecords()) return;

clang/test/PCH/cxx1y-default-initializer.cpp

@@ -1,10 +1,10 @@
-// RUN: %clang_cc1 -pedantic -std=c++1y %s -o %t
-// RUN: %clang_cc1 -pedantic -std=c++1y -emit-pch %s -o %t
-// RUN: %clang_cc1 -pedantic -std=c++1y -include-pch %t -verify %s
+// RUN: %clang_cc1 -pedantic -std=c++1y -include %s -include %s -verify %s
+// RUN: %clang_cc1 -pedantic -std=c++1y -emit-pch -o %t.1 %s
+// RUN: %clang_cc1 -pedantic -std=c++1y -include-pch %t.1 -emit-pch -o %t.2 %s
+// RUN: %clang_cc1 -pedantic -std=c++1y -include-pch %t.2 -verify %s
 
-#ifndef HEADER_INCLUDED
-
-#define HEADER_INCLUDED
+#ifndef HEADER_1
+#define HEADER_1
 
 struct A {
   int x;
@@ -19,6 +19,20 @@ struct B {
   constexpr B(int k) : z1(k) {}
 };
 
+template<typename T> struct C {
+  constexpr C() {}
+  T c = T();
+  struct U {};
+};
+// Instantiate C<int> but not the default initializer.
+C<int>::U ciu;
+
+#elif !defined(HEADER_2)
+#define HEADER_2
+
+// Instantiate the default initializer now, should create an update record.
+C<int> ci;
+
 #else
 
 static_assert(A{}.z == 3, "");
@@ -27,5 +41,6 @@ static_assert(A{.y = 5}.z == 5, ""); // expected-warning {{C99}}
 static_assert(A{3, .y = 1}.z == 4, ""); // expected-warning {{C99}}
 static_assert(make<int>().z == 3, "");
 static_assert(make<int>(12).z == 15, "");
+static_assert(C<int>().c == 0, "");
 
 #endif