Ensure that type definitions present in just-loaded modules are

visible.

The basic problem here is that a given translation unit can use
forward declarations to form pointers to a given type, say,

  class X;
  X *x;

and then import a module that includes a definition of X:

  import XDef;

We will then fail when attempting to access a member of X, e.g., 

  x->method()

because the AST reader did not know to look for a default of a class
named X within the new module.

This implementation is a bit of a C-centric hack, because the only
definitions that can have this property are enums, structs, unions,
Objective-C classes, and Objective-C protocols, and all of those are
either visible at the top-level or can't be defined later. Hence, we
can use the out-of-date-ness of the name and the identifier-update
mechanism to force the update.

In C++, we will not be so lucky, and will need a more advanced
solution, because the definitions could be in namespaces defined in
two different modules, e.g.,

  // module 1
  namespace N { struct X; }

  // module 2
  namespace N { struct X { /* ... */ }; }

One possible implementation here is for C++ to extend the information
associated with each identifier table to include the declaration IDs
of any definitions associated with that name, regardless of
context. We would have to eagerly load those definitions.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174794 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 59 insertions, 18 deletions

diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index cdf921de4a..85ed3ba7db 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -2612,6 +2612,16 @@ void TagDecl::completeDefinition() {
 TagDecl *TagDecl::getDefinition() const {
   if (isCompleteDefinition())
     return const_cast<TagDecl *>(this);
+
+  // If it's possible for us to have an out-of-date definition, check now.
+  if (MayHaveOutOfDateDef) {
+    if (IdentifierInfo *II = getIdentifier()) {
+      if (II->isOutOfDate()) {
+        updateOutOfDate(*II);
+      }
+    }
+  }
+
   if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(this))
     return CXXRD->getDefinition();
 
@@ -2668,14 +2678,17 @@ EnumDecl *EnumDecl::Create(ASTContext &C, DeclContext *DC,
                            bool IsScopedUsingClassTag, bool IsFixed) {
   EnumDecl *Enum = new (C) EnumDecl(DC, StartLoc, IdLoc, Id, PrevDecl,
                                     IsScoped, IsScopedUsingClassTag, IsFixed);
+  Enum->MayHaveOutOfDateDef = C.getLangOpts().Modules;
   C.getTypeDeclType(Enum, PrevDecl);
   return Enum;
 }
 
 EnumDecl *EnumDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
   void *Mem = AllocateDeserializedDecl(C, ID, sizeof(EnumDecl));
-  return new (Mem) EnumDecl(0, SourceLocation(), SourceLocation(), 0, 0,
-                            false, false, false);
+  EnumDecl *Enum = new (Mem) EnumDecl(0, SourceLocation(), SourceLocation(),
+                                      0, 0, false, false, false);
+  Enum->MayHaveOutOfDateDef = C.getLangOpts().Modules;
+  return Enum;
 }
 
 void EnumDecl::completeDefinition(QualType NewType,
@@ -2743,14 +2756,18 @@ RecordDecl *RecordDecl::Create(const ASTContext &C, TagKind TK, DeclContext *DC,
                                IdentifierInfo *Id, RecordDecl* PrevDecl) {
   RecordDecl* R = new (C) RecordDecl(Record, TK, DC, StartLoc, IdLoc, Id,
                                      PrevDecl);
+  R->MayHaveOutOfDateDef = C.getLangOpts().Modules;
+
   C.getTypeDeclType(R, PrevDecl);
   return R;
 }
 
 RecordDecl *RecordDecl::CreateDeserialized(const ASTContext &C, unsigned ID) {
   void *Mem = AllocateDeserializedDecl(C, ID, sizeof(RecordDecl));
-  return new (Mem) RecordDecl(Record, TTK_Struct, 0, SourceLocation(),
-                              SourceLocation(), 0, 0);
+  RecordDecl *R = new (Mem) RecordDecl(Record, TTK_Struct, 0, SourceLocation(),
+                                       SourceLocation(), 0, 0);
+  R->MayHaveOutOfDateDef = C.getLangOpts().Modules;
+  return R;
 }
 
 bool RecordDecl::isInjectedClassName() const {
diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index e1202c23a8..2073658549 100644
--- a/lib/AST/DeclBase.cpp
+++ b/lib/AST/DeclBase.cpp
@@ -40,6 +40,10 @@ using namespace clang;
 #define ABSTRACT_DECL(DECL)
 #include "clang/AST/DeclNodes.inc"
 
+void Decl::updateOutOfDate(IdentifierInfo &II) const {
+  getASTContext().getExternalSource()->updateOutOfDateIdentifier(II);
+}
+
 void *Decl::AllocateDeserializedDecl(const ASTContext &Context, 
                                      unsigned ID,
                                      unsigned Size) {
diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index 90a2b4ab46..4dd3694bc4 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -87,6 +87,7 @@ CXXRecordDecl *CXXRecordDecl::Create(const ASTContext &C, TagKind TK,
                                      bool DelayTypeCreation) {
   CXXRecordDecl* R = new (C) CXXRecordDecl(CXXRecord, TK, DC, StartLoc, IdLoc,
                                            Id, PrevDecl);
+  R->MayHaveOutOfDateDef = C.getLangOpts().Modules;
 
   // FIXME: DelayTypeCreation seems like such a hack
   if (!DelayTypeCreation)
@@ -101,6 +102,7 @@ CXXRecordDecl *CXXRecordDecl::CreateLambda(const ASTContext &C, DeclContext *DC,
                                            0, 0);
   R->IsBeingDefined = true;
   R->DefinitionData = new (C) struct LambdaDefinitionData(R, Info, Dependent);
+  R->MayHaveOutOfDateDef = false;
   C.getTypeDeclType(R, /*PrevDecl=*/0);
   return R;
 }
@@ -108,8 +110,11 @@ CXXRecordDecl *CXXRecordDecl::CreateLambda(const ASTContext &C, DeclContext *DC,
 CXXRecordDecl *
 CXXRecordDecl::CreateDeserialized(const ASTContext &C, unsigned ID) {
   void *Mem = AllocateDeserializedDecl(C, ID, sizeof(CXXRecordDecl));
-  return new (Mem) CXXRecordDecl(CXXRecord, TTK_Struct, 0, SourceLocation(),
-                                 SourceLocation(), 0, 0);
+  CXXRecordDecl *R = new (Mem) CXXRecordDecl(CXXRecord, TTK_Struct, 0,
+                                             SourceLocation(), SourceLocation(),
+                                             0, 0);
+  R->MayHaveOutOfDateDef = false;
+  return R;
 }
 
 void
diff --git a/lib/AST/DeclObjC.cpp b/lib/AST/DeclObjC.cpp
index b99c45ccfb..ce765a7bf5 100644
--- a/lib/AST/DeclObjC.cpp
+++ b/lib/AST/DeclObjC.cpp
@@ -301,8 +301,8 @@ void ObjCInterfaceDecl::mergeClassExtensionProtocolList(
 
 void ObjCInterfaceDecl::allocateDefinitionData() {
   assert(!hasDefinition() && "ObjC class already has a definition");
-  Data = new (getASTContext()) DefinitionData();
-  Data->Definition = this;
+  Data.setPointer(new (getASTContext()) DefinitionData());
+  Data.getPointer()->Definition = this;
 
   // Make the type point at the definition, now that we have one.
   if (TypeForDecl)
@@ -1011,6 +1011,7 @@ ObjCInterfaceDecl *ObjCInterfaceDecl::Create(const ASTContext &C,
                                              bool isInternal){
   ObjCInterfaceDecl *Result = new (C) ObjCInterfaceDecl(DC, atLoc, Id, ClassLoc, 
                                                         PrevDecl, isInternal);
+  Result->Data.setInt(!C.getLangOpts().Modules);
   C.getObjCInterfaceType(Result, PrevDecl);
   return Result;
 }
@@ -1018,8 +1019,11 @@ ObjCInterfaceDecl *ObjCInterfaceDecl::Create(const ASTContext &C,
 ObjCInterfaceDecl *ObjCInterfaceDecl::CreateDeserialized(ASTContext &C, 
                                                          unsigned ID) {
   void *Mem = AllocateDeserializedDecl(C, ID, sizeof(ObjCInterfaceDecl));
-  return new (Mem) ObjCInterfaceDecl(0, SourceLocation(), 0, SourceLocation(),
-                                     0, false);
+  ObjCInterfaceDecl *Result = new (Mem) ObjCInterfaceDecl(0, SourceLocation(),
+                                                          0, SourceLocation(),
+                                                          0, false);
+  Result->Data.setInt(!C.getLangOpts().Modules);
+  return Result;
 }
 
 ObjCInterfaceDecl::
@@ -1334,15 +1338,17 @@ ObjCProtocolDecl *ObjCProtocolDecl::Create(ASTContext &C, DeclContext *DC,
                                            ObjCProtocolDecl *PrevDecl) {
   ObjCProtocolDecl *Result 
     = new (C) ObjCProtocolDecl(DC, Id, nameLoc, atStartLoc, PrevDecl);
-  
+  Result->Data.setInt(!C.getLangOpts().Modules);
   return Result;
 }
 
 ObjCProtocolDecl *ObjCProtocolDecl::CreateDeserialized(ASTContext &C, 
                                                        unsigned ID) {
   void *Mem = AllocateDeserializedDecl(C, ID, sizeof(ObjCProtocolDecl));
-  return new (Mem) ObjCProtocolDecl(0, 0, SourceLocation(), SourceLocation(),
-                                    0);
+  ObjCProtocolDecl *Result = new (Mem) ObjCProtocolDecl(0, 0, SourceLocation(),
+                                                        SourceLocation(), 0);
+  Result->Data.setInt(!C.getLangOpts().Modules);
+  return Result;
 }
 
 ObjCProtocolDecl *ObjCProtocolDecl::lookupProtocolNamed(IdentifierInfo *Name) {
@@ -1380,9 +1386,9 @@ ObjCMethodDecl *ObjCProtocolDecl::lookupMethod(Selector Sel,
 }
 
 void ObjCProtocolDecl::allocateDefinitionData() {
-  assert(!Data && "Protocol already has a definition!");
-  Data = new (getASTContext()) DefinitionData;
-  Data->Definition = this;
+  assert(!Data.getPointer() && "Protocol already has a definition!");
+  Data.setPointer(new (getASTContext()) DefinitionData);
+  Data.getPointer()->Definition = this;
 }
 
 void ObjCProtocolDecl::startDefinition() {
diff --git a/lib/AST/DeclTemplate.cpp b/lib/AST/DeclTemplate.cpp
index bd5ab8a5b9..42929aa71d 100644
--- a/lib/AST/DeclTemplate.cpp
+++ b/lib/AST/DeclTemplate.cpp
@@ -728,6 +728,8 @@ ClassTemplateSpecializationDecl::Create(ASTContext &Context, TagKind TK,
                                                    SpecializedTemplate,
                                                    Args, NumArgs,
                                                    PrevDecl);
+  Result->MayHaveOutOfDateDef = false;
+
   Context.getTypeDeclType(Result, PrevDecl);
   return Result;
 }
@@ -737,7 +739,10 @@ ClassTemplateSpecializationDecl::CreateDeserialized(ASTContext &C,
                                                     unsigned ID) {
   void *Mem = AllocateDeserializedDecl(C, ID, 
                                        sizeof(ClassTemplateSpecializationDecl));
-  return new (Mem) ClassTemplateSpecializationDecl(ClassTemplateSpecialization);
+  ClassTemplateSpecializationDecl *Result =
+    new (Mem) ClassTemplateSpecializationDecl(ClassTemplateSpecialization);
+  Result->MayHaveOutOfDateDef = false;
+  return Result;
 }
 
 void
@@ -857,6 +862,7 @@ Create(ASTContext &Context, TagKind TK,DeclContext *DC,
                                                           PrevDecl,
                                                           SequenceNumber);
   Result->setSpecializationKind(TSK_ExplicitSpecialization);
+  Result->MayHaveOutOfDateDef = false;
 
   Context.getInjectedClassNameType(Result, CanonInjectedType);
   return Result;
@@ -867,7 +873,10 @@ ClassTemplatePartialSpecializationDecl::CreateDeserialized(ASTContext &C,
                                                            unsigned ID) {
   void *Mem = AllocateDeserializedDecl(C, ID, 
                 sizeof(ClassTemplatePartialSpecializationDecl));
-  return new (Mem) ClassTemplatePartialSpecializationDecl();
+  ClassTemplatePartialSpecializationDecl *Result
+    = new (Mem) ClassTemplatePartialSpecializationDecl();
+  Result->MayHaveOutOfDateDef = false;
+  return Result;
 }
 
 //===----------------------------------------------------------------------===//