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can use the out-of-date-ness of the name and the identifier-update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

12 files changed, 181 insertions, 38 deletions

diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index cfcbeb2c00..b6a650fea3 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -2496,6 +2496,12 @@ protected:
   /// possible in C++11 or Microsoft extensions mode.
   bool IsFixed : 1;
 
+  /// \brief Indicates whether it is possible for declarations of this kind
+  /// to have an out-of-date definition.
+  ///
+  /// This option is only enabled when modules are enabled.
+  bool MayHaveOutOfDateDef : 1;
+
 private:
   SourceLocation RBraceLoc;
 
diff --git a/include/clang/AST/DeclBase.h b/include/clang/AST/DeclBase.h
index 8d9d4ded54..edacb4d31b 100644
--- a/include/clang/AST/DeclBase.h
+++ b/include/clang/AST/DeclBase.h
@@ -337,7 +337,10 @@ protected:
   static void *AllocateDeserializedDecl(const ASTContext &Context,
                                         unsigned ID,
                                         unsigned Size);
-  
+
+  /// \brief Update a potentially out-of-date declaration.
+  void updateOutOfDate(IdentifierInfo &II) const;
+
 public:
 
   /// \brief Source range that this declaration covers.
diff --git a/include/clang/AST/DeclObjC.h b/include/clang/AST/DeclObjC.h
index 54649575db..a09bcb50d7 100644
--- a/include/clang/AST/DeclObjC.h
+++ b/include/clang/AST/DeclObjC.h
@@ -668,11 +668,14 @@ class ObjCInterfaceDecl : public ObjCContainerDecl
 
   /// \brief Contains a pointer to the data associated with this class,
   /// which will be NULL if this class has not yet been defined.
-  DefinitionData *Data;
+  ///
+  /// The bit indicates when we don't need to check for out-of-date
+  /// declarations. It will be set unless modules are enabled.
+  llvm::PointerIntPair<DefinitionData *, 1, bool> Data;
 
   DefinitionData &data() const {
-    assert(Data != 0 && "Declaration has no definition!");
-    return *Data;
+    assert(Data.getPointer() && "Declaration has no definition!");
+    return *Data.getPointer();
   }
 
   /// \brief Allocate the definition data for this class.
@@ -680,7 +683,7 @@ class ObjCInterfaceDecl : public ObjCContainerDecl
   
   typedef Redeclarable<ObjCInterfaceDecl> redeclarable_base;
   virtual ObjCInterfaceDecl *getNextRedeclaration() { 
-    return RedeclLink.getNext(); 
+    return RedeclLink.getNext();
   }
   virtual ObjCInterfaceDecl *getPreviousDeclImpl() {
     return getPreviousDecl();
@@ -853,24 +856,38 @@ public:
   /// \brief Determine whether this particular declaration of this class is
   /// actually also a definition.
   bool isThisDeclarationADefinition() const { 
-    return Data && Data->Definition == this;
+    return getDefinition() == this;
   }
                           
   /// \brief Determine whether this class has been defined.
-  bool hasDefinition() const { return Data; }
+  bool hasDefinition() const {
+    // 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.
+    if (!Data.getOpaqueValue()) {
+      if (IdentifierInfo *II = getIdentifier()) {
+        if (II->isOutOfDate()) {
+          updateOutOfDate(*II);
+        }
+      }
+    }
+
+    return Data.getPointer();
+  }
                         
   /// \brief Retrieve the definition of this class, or NULL if this class 
   /// has been forward-declared (with \@class) but not yet defined (with 
   /// \@interface).
   ObjCInterfaceDecl *getDefinition() {
-    return hasDefinition()? Data->Definition : 0;
+    return hasDefinition()? Data.getPointer()->Definition : 0;
   }
 
   /// \brief Retrieve the definition of this class, or NULL if this class 
   /// has been forward-declared (with \@class) but not yet defined (with 
   /// \@interface).
   const ObjCInterfaceDecl *getDefinition() const {
-    return hasDefinition()? Data->Definition : 0;
+    return hasDefinition()? Data.getPointer()->Definition : 0;
   }
 
   /// \brief Starts the definition of this Objective-C class, taking it from
@@ -1142,7 +1159,7 @@ public:
   /// ObjCInterfaceDecl node. This is for legacy objective-c \@implementation
   /// declaration without an \@interface declaration.
   bool isImplicitInterfaceDecl() const { 
-    return hasDefinition() ? Data->Definition->isImplicit() : isImplicit(); 
+    return hasDefinition() ? data().Definition->isImplicit() : isImplicit();
   }
 
   /// ClassImplementsProtocol - Checks that 'lProto' protocol
@@ -1319,12 +1336,17 @@ class ObjCProtocolDecl : public ObjCContainerDecl,
     /// \brief Referenced protocols
     ObjCProtocolList ReferencedProtocols;    
   };
-  
-  DefinitionData *Data;
+
+  /// \brief Contains a pointer to the data associated with this class,
+  /// 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.
+  llvm::PointerIntPair<DefinitionData *, 1, bool> Data;
 
   DefinitionData &data() const {
-    assert(Data && "Objective-C protocol has no definition!");
-    return *Data;
+    assert(Data.getPointer() && "Objective-C protocol has no definition!");
+    return *Data.getPointer();
   }
   
   ObjCProtocolDecl(DeclContext *DC, IdentifierInfo *Id,
@@ -1343,7 +1365,7 @@ class ObjCProtocolDecl : public ObjCContainerDecl,
   virtual ObjCProtocolDecl *getMostRecentDeclImpl() {
     return getMostRecentDecl();
   }
-                           
+
 public:
   static ObjCProtocolDecl *Create(ASTContext &C, DeclContext *DC,
                                   IdentifierInfo *Id,
@@ -1394,7 +1416,7 @@ public:
   /// implements.
   void setProtocolList(ObjCProtocolDecl *const*List, unsigned Num,
                        const SourceLocation *Locs, ASTContext &C) {
-    assert(Data && "Protocol is not defined");
+    assert(hasDefinition() && "Protocol is not defined");
     data().ReferencedProtocols.set(List, Num, Locs, C);
   }
 
@@ -1411,16 +1433,30 @@ public:
   }
 
   /// \brief Determine whether this protocol has a definition.
-  bool hasDefinition() const { return Data != 0; }
+  bool hasDefinition() const {
+    // 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.
+    if (!Data.getOpaqueValue()) {
+      if (IdentifierInfo *II = getIdentifier()) {
+        if (II->isOutOfDate()) {
+          updateOutOfDate(*II);
+        }
+      }
+    }
+
+    return Data.getPointer();
+  }
 
   /// \brief Retrieve the definition of this protocol, if any.
   ObjCProtocolDecl *getDefinition() {
-    return Data? Data->Definition : 0;
+    return hasDefinition()? Data.getPointer()->Definition : 0;
   }
 
   /// \brief Retrieve the definition of this protocol, if any.
   const ObjCProtocolDecl *getDefinition() const {
-    return Data? Data->Definition : 0;
+    return hasDefinition()? Data.getPointer()->Definition : 0;
   }
 
   /// \brief Determine whether this particular declaration is also the 
diff --git a/include/clang/AST/ExternalASTSource.h b/include/clang/AST/ExternalASTSource.h
index 5f95c775dc..81fcf242b6 100644
--- a/include/clang/AST/ExternalASTSource.h
+++ b/include/clang/AST/ExternalASTSource.h
@@ -118,6 +118,9 @@ public:
   /// The default implementation of this method is a no-op.
   virtual CXXBaseSpecifier *GetExternalCXXBaseSpecifiers(uint64_t Offset);
 
+  /// \brief Update an out-of-date identifier.
+  virtual void updateOutOfDateIdentifier(IdentifierInfo &II) { }
+
   /// \brief Find all declarations with the given name in the given context,
   /// and add them to the context by calling SetExternalVisibleDeclsForName
   /// or SetNoExternalVisibleDeclsForName.
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;
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/test/Modules/Inputs/def.h b/test/Modules/Inputs/def.h
index 6d06b08125..eb7eb7e59d 100644
--- a/test/Modules/Inputs/def.h
+++ b/test/Modules/Inputs/def.h
@@ -8,4 +8,13 @@
 }
 @end
 
+@interface Def
+- defMethod;
+@end
 
+#ifdef __cplusplus
+class Def2 {
+public:
+  void func();
+};
+#endif
diff --git a/test/Modules/decldef.m b/test/Modules/decldef.m
new file mode 100644
index 0000000000..7fb8a61386
--- /dev/null
+++ b/test/Modules/decldef.m
@@ -0,0 +1,28 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules -fobjc-arc -I %S/Inputs -fmodules-cache-path=%t %s -verify
+
+
+// In other file: expected-note {{previous definition is here}}
+
+@class Def;
+Def *def;
+
+@import decldef;
+A *a1; // expected-error{{unknown type name 'A'}}
+B *b1; // expected-error{{must use 'struct' tag to refer to type 'B'}}
+@import decldef.Decl;
+
+A *a2;
+struct B *b;
+
+void testA(A *a) {
+  a->ivar = 17; // expected-error{{definition of 'A' must be imported from module 'decldef.Def' before it is required}}
+}
+
+void testB() {
+  B b; // Note: redundant error silenced
+}
+
+void testDef() {
+  [def defMethod];
+}
diff --git a/test/Modules/decldef.mm b/test/Modules/decldef.mm
index 97ce72dd35..732c2a27e2 100644
--- a/test/Modules/decldef.mm
+++ b/test/Modules/decldef.mm
@@ -1,9 +1,18 @@
 // RUN: rm -rf %t
-// RUN: %clang_cc1 -fmodules -I %S/Inputs -fmodules-cache-path=%t %s -verify
+// RUN: %clang_cc1 -fmodules -fobjc-arc -I %S/Inputs -fmodules-cache-path=%t %s -verify
 
 
 // In other file: expected-note {{previous definition is here}}
 
+@class Def;
+Def *def;
+class Def2;
+Def2 *def2;
+
+@interface Unrelated
+- defMethod;
+@end
+
 @import decldef;
 A *a1; // expected-error{{unknown type name 'A'}}
 B *b1; // expected-error{{unknown type name 'B'}}
@@ -19,3 +28,11 @@ void testA(A *a) {
 void testB() {
   B b; // Note: redundant error silenced
 }
+
+void testDef() {
+  [def defMethod];
+}
+
+void testDef2() {
+  def2->func();
+}