4 files changed, 155 insertions, 0 deletions
diff --git a/clang/include/clang/AST/DeclCXX.h b/clang/include/clang/AST/DeclCXX.h
index 020ebfb4af9..c8db319f9d9 100644
--- a/clang/include/clang/AST/DeclCXX.h
+++ b/clang/include/clang/AST/DeclCXX.h
@@ -458,6 +458,9 @@ class CXXRecordDecl : public RecordDecl {
     /// \brief Whether we are currently parsing base specifiers.
     unsigned IsParsingBaseSpecifiers : 1;
 
+    /// \brief A hash of parts of the class to help in ODR checking.
+    unsigned ODRHash;
+
     /// \brief The number of base class specifiers in Bases.
     unsigned NumBases;
 
@@ -703,6 +706,9 @@ public:
     return data().IsParsingBaseSpecifiers;
   }
 
+  void computeODRHash();
+  unsigned getODRHash() const { return data().ODRHash; }
+
   /// \brief Sets the base classes of this struct or class.
   void setBases(CXXBaseSpecifier const * const *Bases, unsigned NumBases);
 
diff --git a/clang/include/clang/AST/ODRHash.h b/clang/include/clang/AST/ODRHash.h
new file mode 100644
index 00000000000..f600a17865c
--- /dev/null
+++ b/clang/include/clang/AST/ODRHash.h
@@ -0,0 +1,82 @@
+//===-- ODRHash.h - Hashing to diagnose ODR failures ------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file contains the declaration of the ODRHash class, which calculates
+/// a hash based on AST nodes, which is stable across different runs.
+///
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/DeclarationName.h"
+#include "clang/AST/Type.h"
+#include "clang/AST/TemplateBase.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/PointerUnion.h"
+#include "llvm/ADT/SmallVector.h"
+
+namespace clang {
+
+class Decl;
+class IdentifierInfo;
+class NestedNameSpecifer;
+class Stmt;
+class TemplateParameterList;
+
+// ODRHash is used to calculate a hash based on AST node contents that
+// does not rely on pointer addresses.  This allows the hash to not vary
+// between runs and is usable to detect ODR problems in modules.  To use,
+// construct an ODRHash object, then call Add* methods over the nodes that
+// need to be hashed.  Then call CalculateHash to get the hash value.
+// Typically, only one Add* call is needed.  clear can be called to reuse the
+// object.
+class ODRHash {
+  // Use DenseMaps to convert between Decl and Type pointers and an index value.
+  llvm::DenseMap<const Decl*, unsigned> DeclMap;
+  llvm::DenseMap<const Type*, unsigned> TypeMap;
+
+  // Save space by processing bools at the end.
+  llvm::SmallVector<bool, 128> Bools;
+
+  llvm::FoldingSetNodeID ID;
+
+public:
+  ODRHash() {}
+
+  // Use this for ODR checking classes between modules.  This method compares
+  // more information than the AddDecl class.
+  void AddCXXRecordDecl(const CXXRecordDecl *Record);
+
+  // Process SubDecls of the main Decl.  This method calls the DeclVisitor
+  // while AddDecl does not.
+  void AddSubDecl(const Decl *D);
+
+  // Reset the object for reuse.
+  void clear();
+
+  // Add booleans to ID and uses it to calculate the hash.
+  unsigned CalculateHash();
+
+  // Add AST nodes that need to be processed.
+  void AddDecl(const Decl *D);
+  void AddType(const Type *T);
+  void AddQualType(QualType T);
+  void AddStmt(const Stmt *S);
+  void AddIdentifierInfo(const IdentifierInfo *II);
+  void AddNestedNameSpecifier(const NestedNameSpecifier *NNS);
+  void AddTemplateName(TemplateName Name);
+  void AddDeclarationName(DeclarationName Name);
+  void AddTemplateArgument(TemplateArgument TA);
+  void AddTemplateParameterList(const TemplateParameterList *TPL);
+
+  // Save booleans until the end to lower the size of data to process.
+  void AddBoolean(bool value);
+};
+
+}  // end namespace clang
diff --git a/clang/include/clang/AST/Stmt.h b/clang/include/clang/AST/Stmt.h
index e28675d6a82..defe6c2ac2f 100644
--- a/clang/include/clang/AST/Stmt.h
+++ b/clang/include/clang/AST/Stmt.h
@@ -39,6 +39,7 @@ namespace clang {
   class Expr;
   class IdentifierInfo;
   class LabelDecl;
+  class ODRHash;
   class ParmVarDecl;
   class PrinterHelper;
   struct PrintingPolicy;
@@ -436,6 +437,8 @@ public:
   /// written in the source.
   void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                bool Canonical) const;
+
+  void ProcessODRHash(llvm::FoldingSetNodeID &ID, ODRHash& Hash) const;
 };
 
 /// DeclStmt - Adaptor class for mixing declarations with statements and
diff --git a/clang/include/clang/Basic/DiagnosticSerializationKinds.td b/clang/include/clang/Basic/DiagnosticSerializationKinds.td
index 066a1f5fa68..9371b05c733 100644
--- a/clang/include/clang/Basic/DiagnosticSerializationKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSerializationKinds.td
@@ -117,6 +117,70 @@ def note_module_odr_violation_different_definitions : Note<
 def err_module_odr_violation_different_instantiations : Error<
   "instantiation of %q0 is different in different modules">;
 
+def err_module_odr_violation_mismatch_decl : Error<
+  "%q0 has different definitions in different modules; first difference is "
+  "%select{definition in module '%2'|defined here}1 found "
+  "%select{end of class|public access specifier|private access specifier|"
+  "protected access specifier|friend declaration|enum|"
+  "static assert|typedef|type alias|method|constructor|destructor|"
+  "conversion operator|field|other}3">;
+def note_module_odr_violation_mismatch_decl : Note<"but in '%0' found "
+  "%select{end of class|public access specifier|private access specifier|"
+  "protected access specifier|friend declaration|enum|"
+  "static assert|typedef|type alias|method|constructor|destructor|"
+  "conversion operator|field|other}1">;
+
+def err_module_odr_violation_mismatch_decl_diff : Error<
+  "%q0 has different definitions in different modules; first difference is "
+  "%select{definition in module '%2'|defined here}1 found "
+  "%select{friend %4|enum %4|element %4 in enum %5|"
+  "element %4 in enum %5 with initializer|"
+  "element %4 in enum %5 with no initializer|"
+  "element %4 in enum %5 with initializer|"
+  "enum %4 has %5 element%s5|"
+  "static assert with condition|"
+  "static assert with message|"
+  "static assert with %select{|no}4 message|"
+  "%select{typedef|type alias}4 name %5|"
+  "method named %4|"
+  "method %4 is %select{non-|}5static|"
+  "method %4 is %select{not |}5inline|"
+  "method %4 is %select{not |}5const|"
+  "method %4 has %5 parameter%s5|"
+  "method %4 has %ordinal5 parameter %select{named %7|with no name}6|"
+  "method %4 has %ordinal5 parameter with type %6|"
+  "method %4 has %ordinal5 parameter with default argument|"
+  "method %4 has %ordinal5 parameter with %select{no |}6 default argument|"
+  "method %4 has %select{|no }5body|"
+  "method %4 has different body|"
+  "field %4|"
+  "%select{field|bitfield}5 %4|"
+  "%select{non-mutable|mutable}5 %4}3">;
+def note_module_odr_violation_mismatch_decl_diff : Note<"but in '%0' found "
+  "%select{other friend %2|other enum %2|different element %2 in enum %3|"
+  "element %2 in enum %3 with initializer|"
+  "element %2 in enum %3 with no initializer|"
+  "element %2 in enum %3 with different initializer|"
+  "enum %2 has %3 element%s3|"
+  "static assert with different condition|"
+  "static assert with different message|"
+  "static assert with %select{|no}2 message|"
+  "different %select{typedef|type alias}2 name %3|"
+  "method named %2|"
+  "method %2 is %select{non-|}3static|"
+  "method %2 is %select{not |}3inline|"
+  "method %2 is %select{not |}3const|"
+  "method %2 has %3 parameter%s3|"
+  "method %2 has %ordinal3 parameter %select{named %5|with no name}4|"
+  "method %2 has %ordinal3 parameter with type %4|"
+  "method %2 has %ordinal3 parameter with different default argument|"
+  "method %2 has %ordinal3 parameter with %select{no |}4default argument|"
+  "method %2 has %select{|no }3body|"
+  "method %2 has different body|"
+  "field %2|"
+  "%select{field|bitfield}3 %2|"
+  "%select{non-mutable|mutable}3 %2}1">;
+
 def warn_module_uses_date_time : Warning<
   "%select{precompiled header|module}0 uses __DATE__ or __TIME__">,
   InGroup<DiagGroup<"pch-date-time">>;