Implement DR1330 in C++11 mode, to support libstdc++4.7 which uses it.

We have a new flavor of exception specification, EST_Uninstantiated. A function
type with this exception specification carries a pointer to a FunctionDecl, and
the exception specification for that FunctionDecl is instantiated (if needed)
and used in the place of the function type's exception specification.

When a function template declaration with a non-trivial exception specification
is instantiated, the specialization's exception specification is set to this
new 'uninstantiated' kind rather than being instantiated immediately.

Expr::CanThrow has migrated onto Sema, so it can instantiate exception specs
on-demand. Also, any odr-use of a function triggers the instantiation of its
exception specification (the exception specification could be needed by IRGen).
In passing, fix two places where a DeclRefExpr was created but the corresponding
function was not actually marked odr-used. We used to get away with this, but
don't any more.

Also fix a bug where instantiating an exception specification which refers to
function parameters resulted in a crash. We still have the same bug in default
arguments, which I'll be looking into next.

This, plus a tiny patch to fix libstdc++'s common_type, is enough for clang to
parse (and, in very limited testing, support) all of libstdc++4.7's standard
headers.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154886 91177308-0d34-0410-b5e6-96231b3b80d8

21 files changed, 872 insertions, 541 deletions

diff --git a/include/clang/AST/Expr.h b/include/clang/AST/Expr.h
index a7822fab1c..b0b9b0fd6f 100644
--- a/include/clang/AST/Expr.h
+++ b/include/clang/AST/Expr.h
@@ -581,16 +581,6 @@ public:
   /// member expression.
   static QualType findBoundMemberType(const Expr *expr);
 
-  /// \brief Result type of CanThrow().
-  enum CanThrowResult {
-    CT_Cannot,
-    CT_Dependent,
-    CT_Can
-  };
-  /// \brief Test if this expression, if evaluated, might throw, according to
-  ///        the rules of C++ [expr.unary.noexcept].
-  CanThrowResult CanThrow(ASTContext &C) const;
-
   /// IgnoreImpCasts - Skip past any implicit casts which might
   /// surround this expression.  Only skips ImplicitCastExprs.
   Expr *IgnoreImpCasts() LLVM_READONLY;
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index 7bd367c054..9fd4901672 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -79,6 +79,7 @@ namespace clang {
   class CXXRecordDecl;
   class EnumDecl;
   class FieldDecl;
+  class FunctionDecl;
   class ObjCInterfaceDecl;
   class ObjCProtocolDecl;
   class ObjCMethodDecl;
@@ -2700,7 +2701,8 @@ public:
     ExtProtoInfo() :
       Variadic(false), HasTrailingReturn(false), TypeQuals(0),
       ExceptionSpecType(EST_None), RefQualifier(RQ_None),
-      NumExceptions(0), Exceptions(0), NoexceptExpr(0), ConsumedArguments(0) {}
+      NumExceptions(0), Exceptions(0), NoexceptExpr(0), ExceptionSpecDecl(0),
+      ConsumedArguments(0) {}
 
     FunctionType::ExtInfo ExtInfo;
     bool Variadic : 1;
@@ -2711,6 +2713,7 @@ public:
     unsigned NumExceptions;
     const QualType *Exceptions;
     Expr *NoexceptExpr;
+    FunctionDecl *ExceptionSpecDecl;
     const bool *ConsumedArguments;
   };
 
@@ -2756,6 +2759,10 @@ private:
   // NoexceptExpr - Instead of Exceptions, there may be a single Expr* pointing
   // to the expression in the noexcept() specifier.
 
+  // ExceptionSpecDecl - Instead of Exceptions, there may be a single
+  // FunctionDecl* pointing to the function which should be used to resolve
+  // this function type's exception specification.
+
   // ConsumedArgs - A variable size array, following Exceptions
   // and of length NumArgs, holding flags indicating which arguments
   // are consumed.  This only appears if HasAnyConsumedArgs is true.
@@ -2795,6 +2802,8 @@ public:
       EPI.Exceptions = exception_begin();
     } else if (EPI.ExceptionSpecType == EST_ComputedNoexcept) {
       EPI.NoexceptExpr = getNoexceptExpr();
+    } else if (EPI.ExceptionSpecType == EST_Uninstantiated) {
+      EPI.ExceptionSpecDecl = getExceptionSpecDecl();
     }
     if (hasAnyConsumedArgs())
       EPI.ConsumedArguments = getConsumedArgsBuffer();
@@ -2838,9 +2847,14 @@ public:
     // NoexceptExpr sits where the arguments end.
     return *reinterpret_cast<Expr *const *>(arg_type_end());
   }
+  FunctionDecl *getExceptionSpecDecl() const {
+    if (getExceptionSpecType() != EST_Uninstantiated)
+      return 0;
+    return *reinterpret_cast<FunctionDecl * const *>(arg_type_end());
+  }
   bool isNothrow(ASTContext &Ctx) const {
     ExceptionSpecificationType EST = getExceptionSpecType();
-    assert(EST != EST_Delayed);
+    assert(EST != EST_Delayed && EST != EST_Uninstantiated);
     if (EST == EST_DynamicNone || EST == EST_BasicNoexcept)
       return true;
     if (EST != EST_ComputedNoexcept)
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index baaddcfeb2..779af403a6 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2583,6 +2583,8 @@ def note_template_enum_def_here : Note<
   "in instantiation of enumeration %q0 requested here">;
 def note_template_type_alias_instantiation_here : Note<
   "in instantiation of template type alias %0 requested here">;
+def note_template_exception_spec_instantiation_here : Note<
+  "in instantiation of exception specification for %0 requested here">;
   
 def note_default_arg_instantiation_here : Note<
   "in instantiation of default argument for '%0' required here">;
diff --git a/include/clang/Basic/ExceptionSpecificationType.h b/include/clang/Basic/ExceptionSpecificationType.h
index 98cfd297ad..e911bde191 100644
--- a/include/clang/Basic/ExceptionSpecificationType.h
+++ b/include/clang/Basic/ExceptionSpecificationType.h
@@ -16,7 +16,7 @@
 
 namespace clang {
 
-/// \brief The various types of exception specifications that exist in C++0x.
+/// \brief The various types of exception specifications that exist in C++11.
 enum ExceptionSpecificationType {
   EST_None,             ///< no exception specification
   EST_DynamicNone,      ///< throw()
@@ -24,7 +24,8 @@ enum ExceptionSpecificationType {
   EST_MSAny,            ///< Microsoft throw(...) extension
   EST_BasicNoexcept,    ///< noexcept
   EST_ComputedNoexcept, ///< noexcept(expression)
-  EST_Delayed           ///< not known yet
+  EST_Delayed,          ///< not known yet
+  EST_Uninstantiated    ///< not instantiated yet
 };
 
 inline bool isDynamicExceptionSpec(ExceptionSpecificationType ESpecType) {
@@ -35,6 +36,19 @@ inline bool isNoexceptExceptionSpec(ExceptionSpecificationType ESpecType) {
   return ESpecType == EST_BasicNoexcept || ESpecType == EST_ComputedNoexcept;
 }
 
+/// \brief Possible results from evaluation of a noexcept expression.
+enum CanThrowResult {
+  CT_Cannot,
+  CT_Dependent,
+  CT_Can
+};
+
+inline CanThrowResult mergeCanThrow(CanThrowResult CT1, CanThrowResult CT2) {
+  // CanThrowResult constants are ordered so that the maximum is the correct
+  // merge result.
+  return CT1 > CT2 ? CT1 : CT2;
+}
+
 } // end namespace clang
 
 #endif // LLVM_CLANG_BASIC_EXCEPTIONSPECIFICATIONTYPE_H
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 7de59e0f5d..c845ee5549 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -907,6 +907,9 @@ public:
   DeclarationNameInfo GetNameForDeclarator(Declarator &D);
   DeclarationNameInfo GetNameFromUnqualifiedId(const UnqualifiedId &Name);
   static QualType GetTypeFromParser(ParsedType Ty, TypeSourceInfo **TInfo = 0);
+  CanThrowResult canThrow(const Expr *E);
+  const FunctionProtoType *ResolveExceptionSpec(SourceLocation Loc,
+                                                const FunctionProtoType *FPT);
   bool CheckSpecifiedExceptionType(QualType T, const SourceRange &Range);
   bool CheckDistantExceptionSpec(QualType T);
   bool CheckEquivalentExceptionSpec(FunctionDecl *Old, FunctionDecl *New);
@@ -3050,7 +3053,7 @@ public:
   /// implicitly-declared special member functions.
   class ImplicitExceptionSpecification {
     // Pointer to allow copying
-    ASTContext *Context;
+    Sema *Self;
     // We order exception specifications thus:
     // noexcept is the most restrictive, but is only used in C++0x.
     // throw() comes next.
@@ -3074,9 +3077,9 @@ public:
     }
 
   public:
-    explicit ImplicitExceptionSpecification(ASTContext &Context)
-      : Context(&Context), ComputedEST(EST_BasicNoexcept) {
-      if (!Context.getLangOpts().CPlusPlus0x)
+    explicit ImplicitExceptionSpecification(Sema &Self)
+      : Self(&Self), ComputedEST(EST_BasicNoexcept) {
+      if (!Self.Context.getLangOpts().CPlusPlus0x)
         ComputedEST = EST_DynamicNone;
     }
 
@@ -3094,7 +3097,7 @@ public:
     const QualType *data() const { return Exceptions.data(); }
 
     /// \brief Integrate another called method into the collected data.
-    void CalledDecl(CXXMethodDecl *Method);
+    void CalledDecl(SourceLocation CallLoc, CXXMethodDecl *Method);
 
     /// \brief Integrate an invoked expression into the collected data.
     void CalledExpr(Expr *E);
@@ -5194,7 +5197,11 @@ public:
 
       /// We are checking the validity of a default template argument that
       /// has been used when naming a template-id.
-      DefaultTemplateArgumentChecking
+      DefaultTemplateArgumentChecking,
+
+      /// We are instantiating the exception specification for a function
+      /// template which was deferred until it was needed.
+      ExceptionSpecInstantiation
     } Kind;
 
     /// \brief The point of instantiation within the source code.
@@ -5242,6 +5249,7 @@ public:
 
       switch (X.Kind) {
       case TemplateInstantiation:
+      case ExceptionSpecInstantiation:
         return true;
 
       case PriorTemplateArgumentSubstitution:
@@ -5359,6 +5367,13 @@ public:
                           Decl *Entity,
                           SourceRange InstantiationRange = SourceRange());
 
+    struct ExceptionSpecification {};
+    /// \brief Note that we are instantiating an exception specification
+    /// of a function template.
+    InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
+                          FunctionDecl *Entity, ExceptionSpecification,
+                          SourceRange InstantiationRange = SourceRange());
+
     /// \brief Note that we are instantiating a default argument in a
     /// template-id.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
@@ -5658,6 +5673,8 @@ public:
              TemplateArgumentListInfo &Result,
              const MultiLevelTemplateArgumentList &TemplateArgs);
 
+  void InstantiateExceptionSpec(SourceLocation PointOfInstantiation,
+                                FunctionDecl *Function);
   void InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
                                      FunctionDecl *Function,
                                      bool Recursive = false,
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 887beac4b0..65ddc059fa 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -2194,6 +2194,8 @@ ASTContext::getFunctionType(QualType ResultTy,
     Size += EPI.NumExceptions * sizeof(QualType);
   else if (EPI.ExceptionSpecType == EST_ComputedNoexcept) {
     Size += sizeof(Expr*);
+  } else if (EPI.ExceptionSpecType == EST_Uninstantiated) {
+    Size += sizeof(FunctionDecl*);
   }
   if (EPI.ConsumedArguments)
     Size += NumArgs * sizeof(bool);
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 9556b1acb9..fcde5429b3 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -1996,331 +1996,6 @@ QualType Expr::findBoundMemberType(const Expr *expr) {
   return QualType();
 }
 
-static Expr::CanThrowResult MergeCanThrow(Expr::CanThrowResult CT1,
-                                          Expr::CanThrowResult CT2) {
-  // CanThrowResult constants are ordered so that the maximum is the correct
-  // merge result.
-  return CT1 > CT2 ? CT1 : CT2;
-}
-
-static Expr::CanThrowResult CanSubExprsThrow(ASTContext &C, const Expr *CE) {
-  Expr *E = const_cast<Expr*>(CE);
-  Expr::CanThrowResult R = Expr::CT_Cannot;
-  for (Expr::child_range I = E->children(); I && R != Expr::CT_Can; ++I) {
-    R = MergeCanThrow(R, cast<Expr>(*I)->CanThrow(C));
-  }
-  return R;
-}
-
-static Expr::CanThrowResult CanCalleeThrow(ASTContext &Ctx, const Expr *E,
-                                           const Decl *D,
-                                           bool NullThrows = true) {
-  if (!D)
-    return NullThrows ? Expr::CT_Can : Expr::CT_Cannot;
-
-  // See if we can get a function type from the decl somehow.
-  const ValueDecl *VD = dyn_cast<ValueDecl>(D);
-  if (!VD) // If we have no clue what we're calling, assume the worst.
-    return Expr::CT_Can;
-
-  // As an extension, we assume that __attribute__((nothrow)) functions don't
-  // throw.
-  if (isa<FunctionDecl>(D) && D->hasAttr<NoThrowAttr>())
-    return Expr::CT_Cannot;
-
-  QualType T = VD->getType();
-  const FunctionProtoType *FT;
-  if ((FT = T->getAs<FunctionProtoType>())) {
-  } else if (const PointerType *PT = T->getAs<PointerType>())
-    FT = PT->getPointeeType()->getAs<FunctionProtoType>();
-  else if (const ReferenceType *RT = T->getAs<ReferenceType>())
-    FT = RT->getPointeeType()->getAs<FunctionProtoType>();
-  else if (const MemberPointerType *MT = T->getAs<MemberPointerType>())
-    FT = MT->getPointeeType()->getAs<FunctionProtoType>();
-  else if (const BlockPointerType *BT = T->getAs<BlockPointerType>())
-    FT = BT->getPointeeType()->getAs<FunctionProtoType>();
-
-  if (!FT)
-    return Expr::CT_Can;
-
-  if (FT->getExceptionSpecType() == EST_Delayed) {
-    assert(isa<CXXConstructorDecl>(D) &&
-           "only constructor exception specs can be unknown");
-    Ctx.getDiagnostics().Report(E->getLocStart(),
-                                diag::err_exception_spec_unknown)
-      << E->getSourceRange();
-    return Expr::CT_Can;
-  }
-
-  return FT->isNothrow(Ctx) ? Expr::CT_Cannot : Expr::CT_Can;
-}
-
-static Expr::CanThrowResult CanDynamicCastThrow(const CXXDynamicCastExpr *DC) {
-  if (DC->isTypeDependent())
-    return Expr::CT_Dependent;
-
-  if (!DC->getTypeAsWritten()->isReferenceType())
-    return Expr::CT_Cannot;
-
-  if (DC->getSubExpr()->isTypeDependent())
-    return Expr::CT_Dependent;
-
-  return DC->getCastKind() == clang::CK_Dynamic? Expr::CT_Can : Expr::CT_Cannot;
-}
-
-static Expr::CanThrowResult CanTypeidThrow(ASTContext &C,
-                                           const CXXTypeidExpr *DC) {
-  if (DC->isTypeOperand())
-    return Expr::CT_Cannot;
-
-  Expr *Op = DC->getExprOperand();
-  if (Op->isTypeDependent())
-    return Expr::CT_Dependent;
-
-  const RecordType *RT = Op->getType()->getAs<RecordType>();
-  if (!RT)
-    return Expr::CT_Cannot;
-
-  if (!cast<CXXRecordDecl>(RT->getDecl())->isPolymorphic())
-    return Expr::CT_Cannot;
-
-  if (Op->Classify(C).isPRValue())
-    return Expr::CT_Cannot;
-
-  return Expr::CT_Can;
-}
-
-Expr::CanThrowResult Expr::CanThrow(ASTContext &C) const {
-  // C++ [expr.unary.noexcept]p3:
-  //   [Can throw] if in a potentially-evaluated context the expression would
-  //   contain:
-  switch (getStmtClass()) {
-  case CXXThrowExprClass:
-    //   - a potentially evaluated throw-expression
-    return CT_Can;
-
-  case CXXDynamicCastExprClass: {
-    //   - a potentially evaluated dynamic_cast expression dynamic_cast<T>(v),
-    //     where T is a reference type, that requires a run-time check
-    CanThrowResult CT = CanDynamicCastThrow(cast<CXXDynamicCastExpr>(this));
-    if (CT == CT_Can)
-      return CT;
-    return MergeCanThrow(CT, CanSubExprsThrow(C, this));
-  }
-
-  case CXXTypeidExprClass:
-    //   - a potentially evaluated typeid expression applied to a glvalue
-    //     expression whose type is a polymorphic class type
-    return CanTypeidThrow(C, cast<CXXTypeidExpr>(this));
-
-    //   - a potentially evaluated call to a function, member function, function
-    //     pointer, or member function pointer that does not have a non-throwing
-    //     exception-specification
-  case CallExprClass:
-  case CXXMemberCallExprClass:
-  case CXXOperatorCallExprClass:
-  case UserDefinedLiteralClass: {
-    const CallExpr *CE = cast<CallExpr>(this);
-    CanThrowResult CT;
-    if (isTypeDependent())
-      CT = CT_Dependent;
-    else if (isa<CXXPseudoDestructorExpr>(CE->getCallee()->IgnoreParens()))
-      CT = CT_Cannot;
-    else
-      CT = CanCalleeThrow(C, this, CE->getCalleeDecl());
-    if (CT == CT_Can)
-      return CT;
-    return MergeCanThrow(CT, CanSubExprsThrow(C, this));
-  }
-
-  case CXXConstructExprClass:
-  case CXXTemporaryObjectExprClass: {
-    CanThrowResult CT = CanCalleeThrow(C, this,
-        cast<CXXConstructExpr>(this)->getConstructor());
-    if (CT == CT_Can)
-      return CT;
-    return MergeCanThrow(CT, CanSubExprsThrow(C, this));
-  }
-
-  case LambdaExprClass: {
-    const LambdaExpr *Lambda = cast<LambdaExpr>(this);
-    CanThrowResult CT = Expr::CT_Cannot;
-    for (LambdaExpr::capture_init_iterator Cap = Lambda->capture_init_begin(),
-                                        CapEnd = Lambda->capture_init_end();
-         Cap != CapEnd; ++Cap)
-      CT = MergeCanThrow(CT, (*Cap)->CanThrow(C));
-    return CT;
-  }
-
-  case CXXNewExprClass: {
-    CanThrowResult CT;
-    if (isTypeDependent())
-      CT = CT_Dependent;
-    else
-      CT = CanCalleeThrow(C, this, cast<CXXNewExpr>(this)->getOperatorNew());
-    if (CT == CT_Can)
-      return CT;
-    return MergeCanThrow(CT, CanSubExprsThrow(C, this));
-  }
-
-  case CXXDeleteExprClass: {
-    CanThrowResult CT;
-    QualType DTy = cast<CXXDeleteExpr>(this)->getDestroyedType();
-    if (DTy.isNull() || DTy->isDependentType()) {
-      CT = CT_Dependent;
-    } else {
-      CT = CanCalleeThrow(C, this,
-                          cast<CXXDeleteExpr>(this)->getOperatorDelete());
-      if (const RecordType *RT = DTy->getAs<RecordType>()) {
-        const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
-        CT = MergeCanThrow(CT, CanCalleeThrow(C, this, RD->getDestructor()));
-      }
-      if (CT == CT_Can)
-        return CT;
-    }
-    return MergeCanThrow(CT, CanSubExprsThrow(C, this));
-  }
-
-  case CXXBindTemporaryExprClass: {
-    // The bound temporary has to be destroyed again, which might throw.
-    CanThrowResult CT = CanCalleeThrow(C, this,
-      cast<CXXBindTemporaryExpr>(this)->getTemporary()->getDestructor());
-    if (CT == CT_Can)
-      return CT;
-    return MergeCanThrow(CT, CanSubExprsThrow(C, this));
-  }
-
-    // ObjC message sends are like function calls, but never have exception
-    // specs.
-  case ObjCMessageExprClass:
-  case ObjCPropertyRefExprClass:
-  case ObjCSubscriptRefExprClass:
-    return CT_Can;
-
-    // All the ObjC literals that are implemented as calls are
-    // potentially throwing unless we decide to close off that
-    // possibility.
-  case ObjCArrayLiteralClass:
-  case ObjCDictionaryLiteralClass:
-  case ObjCNumericLiteralClass:
-    return CT_Can;
-
-    // Many other things have subexpressions, so we have to test those.
-    // Some are simple:
-  case ConditionalOperatorClass:
-  case CompoundLiteralExprClass:
-  case CXXConstCastExprClass:
-  case CXXDefaultArgExprClass:
-  case CXXReinterpretCastExprClass:
-  case DesignatedInitExprClass:
-  case ExprWithCleanupsClass:
-  case ExtVectorElementExprClass:
-  case InitListExprClass:
-  case MemberExprClass:
-  case ObjCIsaExprClass:
-  case ObjCIvarRefExprClass:
-  case ParenExprClass:
-  case ParenListExprClass:
-  case ShuffleVectorExprClass:
-  case VAArgExprClass:
-    return CanSubExprsThrow(C, this);
-
-    // Some might be dependent for other reasons.
-  case ArraySubscriptExprClass:
-  case BinaryOperatorClass:
-  case CompoundAssignOperatorClass:
-  case CStyleCastExprClass:
-  case CXXStaticCastExprClass:
-  case CXXFunctionalCastExprClass:
-  case ImplicitCastExprClass:
-  case MaterializeTemporaryExprClass:
-  case UnaryOperatorClass: {
-    CanThrowResult CT = isTypeDependent() ? CT_Dependent : CT_Cannot;
-    return MergeCanThrow(CT, CanSubExprsThrow(C, this));
-  }
-
-    // FIXME: We should handle StmtExpr, but that opens a MASSIVE can of worms.
-  case StmtExprClass:
-    return CT_Can;
-
-  case ChooseExprClass:
-    if (isTypeDependent() || isValueDependent())
-      return CT_Dependent;
-    return cast<ChooseExpr>(this)->getChosenSubExpr(C)->CanThrow(C);
-
-  case GenericSelectionExprClass:
-    if (cast<GenericSelectionExpr>(this)->isResultDependent())
-      return CT_Dependent;
-    return cast<GenericSelectionExpr>(this)->getResultExpr()->CanThrow(C);
-
-    // Some expressions are always dependent.
-  case CXXDependentScopeMemberExprClass:
-  case CXXUnresolvedConstructExprClass:
-  case DependentScopeDeclRefExprClass:
-    return CT_Dependent;
-
-  case AtomicExprClass:
-  case AsTypeExprClass:
-  case BinaryConditionalOperatorClass:
-  case BlockExprClass:
-  case CUDAKernelCallExprClass:
-  case DeclRefExprClass:
-  case ObjCBridgedCastExprClass:
-  case ObjCIndirectCopyRestoreExprClass:
-  case ObjCProtocolExprClass:
-  case ObjCSelectorExprClass:
-  case OffsetOfExprClass:
-  case PackExpansionExprClass:
-  case PseudoObjectExprClass:
-  case SubstNonTypeTemplateParmExprClass:
-  case SubstNonTypeTemplateParmPackExprClass:
-  case UnaryExprOrTypeTraitExprClass:
-  case UnresolvedLookupExprClass:
-  case UnresolvedMemberExprClass:
-    // FIXME: Can any of the above throw?  If so, when?
-    return CT_Cannot;
-
-  case AddrLabelExprClass:
-  case ArrayTypeTraitExprClass:
-  case BinaryTypeTraitExprClass:
-  case TypeTraitExprClass:
-  case CXXBoolLiteralExprClass:
-  case CXXNoexceptExprClass:
-  case CXXNullPtrLiteralExprClass:
-  case CXXPseudoDestructorExprClass:
-  case CXXScalarValueInitExprClass:
-  case CXXThisExprClass:
-  case CXXUuidofExprClass:
-  case CharacterLiteralClass:
-  case ExpressionTraitExprClass:
-  case FloatingLiteralClass:
-  case GNUNullExprClass:
-  case ImaginaryLiteralClass:
-  case ImplicitValueInitExprClass:
-  case IntegerLiteralClass:
-  case ObjCEncodeExprClass:
-  case ObjCStringLiteralClass:
-  case ObjCBoolLiteralExprClass:
-  case OpaqueValueExprClass:
-  case PredefinedExprClass:
-  case SizeOfPackExprClass:
-  case StringLiteralClass:
-  case UnaryTypeTraitExprClass:
-    // These expressions can never throw.
-    return CT_Cannot;
-
-#define STMT(CLASS, PARENT) case CLASS##Class:
-#define STMT_RANGE(Base, First, Last)
-#define LAST_STMT_RANGE(BASE, FIRST, LAST)
-#define EXPR(CLASS, PARENT)
-#define ABSTRACT_STMT(STMT)
-#include "clang/AST/StmtNodes.inc"
-  case NoStmtClass:
-    llvm_unreachable("Invalid class for expression");
-  }
-  llvm_unreachable("Bogus StmtClass");
-}
-
 Expr* Expr::IgnoreParens() {
   Expr* E = this;
   while (true) {
diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index c82aeaadd4..10c1adc875 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -1546,6 +1546,13 @@ FunctionProtoType::FunctionProtoType(QualType result, const QualType *args,
       else if (epi.NoexceptExpr->isInstantiationDependent())
         setInstantiationDependent();
     }
+  } else if (getExceptionSpecType() == EST_Uninstantiated) {
+    // Store the function decl from which we will resolve our
+    // exception specification.
+    FunctionDecl **slot = reinterpret_cast<FunctionDecl**>(argSlot + numArgs);
+    *slot = epi.ExceptionSpecDecl;
+    // This exception specification doesn't make the type dependent, because
+    // it's not instantiated as part of instantiating the type.
   }
 
   if (epi.ConsumedArguments) {
@@ -1629,6 +1636,8 @@ void FunctionProtoType::Profile(llvm::FoldingSetNodeID &ID, QualType Result,
       ID.AddPointer(epi.Exceptions[i].getAsOpaquePtr());
   } else if (epi.ExceptionSpecType == EST_ComputedNoexcept && epi.NoexceptExpr){
     epi.NoexceptExpr->Profile(ID, Context, false);
+  } else if (epi.ExceptionSpecType == EST_Uninstantiated) {
+    ID.AddPointer(epi.ExceptionSpecDecl->getCanonicalDecl());
   }
   if (epi.ConsumedArguments) {
     for (unsigned i = 0; i != NumArgs; ++i)
diff --git a/lib/Analysis/CFG.cpp b/lib/Analysis/CFG.cpp
index f4d9a354a5..2f1f1cb4e4 100644
--- a/lib/Analysis/CFG.cpp
+++ b/lib/Analysis/CFG.cpp
@@ -1284,7 +1284,8 @@ static bool CanThrow(Expr *E, ASTContext &Ctx) {
   const FunctionType *FT = Ty->getAs<FunctionType>();
   if (FT) {
     if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT))
-      if (Proto->isNothrow(Ctx))
+      if (Proto->getExceptionSpecType() != EST_Uninstantiated &&
+          Proto->isNothrow(Ctx))
         return false;
   }
   return true;
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 8fe28e9555..f0f52c7546 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -125,14 +125,17 @@ namespace {
   }
 }
 
-void Sema::ImplicitExceptionSpecification::CalledDecl(CXXMethodDecl *Method) {
-  assert(Context && "ImplicitExceptionSpecification without an ASTContext");
+void Sema::ImplicitExceptionSpecification::CalledDecl(SourceLocation CallLoc,
+                                                      CXXMethodDecl *Method) {
   // If we have an MSAny or unknown spec already, don't bother.
   if (!Method || ComputedEST == EST_MSAny || ComputedEST == EST_Delayed)
     return;
 
   const FunctionProtoType *Proto
     = Method->getType()->getAs<FunctionProtoType>();
+  Proto = Self->ResolveExceptionSpec(CallLoc, Proto);
+  if (!Proto)
+    return;
 
   ExceptionSpecificationType EST = Proto->getExceptionSpecType();
 
@@ -164,7 +167,8 @@ void Sema::ImplicitExceptionSpecification::CalledDecl(CXXMethodDecl *Method) {
 
   // Check out noexcept specs.
   if (EST == EST_ComputedNoexcept) {
-    FunctionProtoType::NoexceptResult NR = Proto->getNoexceptSpec(*Context);
+    FunctionProtoType::NoexceptResult NR =
+        Proto->getNoexceptSpec(Self->Context);
     assert(NR != FunctionProtoType::NR_NoNoexcept &&
            "Must have noexcept result for EST_ComputedNoexcept.");
     assert(NR != FunctionProtoType::NR_Dependent &&
@@ -188,7 +192,7 @@ void Sema::ImplicitExceptionSpecification::CalledDecl(CXXMethodDecl *Method) {
   for (FunctionProtoType::exception_iterator E = Proto->exception_begin(),
                                           EEnd = Proto->exception_end();
        E != EEnd; ++E)
-    if (ExceptionsSeen.insert(Context->getCanonicalType(*E)))
+    if (ExceptionsSeen.insert(Self->Context.getCanonicalType(*E)))
       Exceptions.push_back(*E);
 }
 
@@ -217,7 +221,7 @@ void Sema::ImplicitExceptionSpecification::CalledExpr(Expr *E) {
   // implicit definition. For now, we assume that any non-nothrow expression can
   // throw any exception.
 
-  if (E->CanThrow(*Context))
+  if (Self->canThrow(E))
     ComputedEST = EST_None;
 }
 
@@ -3922,7 +3926,7 @@ void Sema::CheckExplicitlyDefaultedCopyConstructor(CXXConstructorDecl *CD) {
     HadError = true;
   }
 
-  ImplicitExceptionSpecification Spec(Context);
+  ImplicitExceptionSpecification Spec(*this);
   bool Const;
   llvm::tie(Spec, Const) =
     ComputeDefaultedCopyCtorExceptionSpecAndConst(CD->getParent());
@@ -4031,7 +4035,7 @@ void Sema::CheckExplicitlyDefaultedCopyAssignment(CXXMethodDecl *MD) {
     HadError = true;
   }
 
-  ImplicitExceptionSpecification Spec(Context);
+  ImplicitExceptionSpecification Spec(*this);
   bool Const;
   llvm::tie(Spec, Const) =
     ComputeDefaultedCopyCtorExceptionSpecAndConst(MD->getParent());
@@ -6814,7 +6818,7 @@ Sema::ComputeDefaultedDefaultCtorExceptionSpec(CXXRecordDecl *ClassDecl) {
   // C++ [except.spec]p14:
   //   An implicitly declared special member function (Clause 12) shall have an 
   //   exception-specification. [...]
-  ImplicitExceptionSpecification ExceptSpec(Context);
+  ImplicitExceptionSpecification ExceptSpec(*this);
   if (ClassDecl->isInvalidDecl())
     return ExceptSpec;
 
@@ -6831,7 +6835,7 @@ Sema::ComputeDefaultedDefaultCtorExceptionSpec(CXXRecordDecl *ClassDecl) {
       // If this is a deleted function, add it anyway. This might be conformant
       // with the standard. This might not. I'm not sure. It might not matter.
       if (Constructor)
-        ExceptSpec.CalledDecl(Constructor);
+        ExceptSpec.CalledDecl(B->getLocStart(), Constructor);
     }
   }
 
@@ -6845,7 +6849,7 @@ Sema::ComputeDefaultedDefaultCtorExceptionSpec(CXXRecordDecl *ClassDecl) {
       // If this is a deleted function, add it anyway. This might be conformant
       // with the standard. This might not. I'm not sure. It might not matter.
       if (Constructor)
-        ExceptSpec.CalledDecl(Constructor);
+        ExceptSpec.CalledDecl(B->getLocStart(), Constructor);
     }
   }
 
@@ -6868,7 +6872,7 @@ Sema::ComputeDefaultedDefaultCtorExceptionSpec(CXXRecordDecl *ClassDecl) {
       // might just be ill-formed because this function attempts to refer to
       // a deleted function here.
       if (Constructor)
-        ExceptSpec.CalledDecl(Constructor);
+        ExceptSpec.CalledDecl(F->getLocation(), Constructor);
     }
   }
 
@@ -6990,6 +6994,7 @@ void Sema::ActOnFinishDelayedMemberInitializers(Decl *D) {
   const FunctionProtoType *CtorTy =
     CtorDecl->getType()->castAs<FunctionProtoType>();
   if (CtorTy->getExceptionSpecType() == EST_Delayed) {
+    // FIXME: Don't do this unless the exception spec is needed.
     ImplicitExceptionSpecification Spec = 
       ComputeDefaultedDefaultCtorExceptionSpec(ClassDecl);
     FunctionProtoType::ExtProtoInfo EPI = Spec.getEPI();
@@ -7190,7 +7195,7 @@ Sema::ComputeDefaultedDtorExceptionSpec(CXXRecordDecl *ClassDecl) {
   // C++ [except.spec]p14: 
   //   An implicitly declared special member function (Clause 12) shall have 
   //   an exception-specification.
-  ImplicitExceptionSpecification ExceptSpec(Context);
+  ImplicitExceptionSpecification ExceptSpec(*this);
   if (ClassDecl->isInvalidDecl())
     return ExceptSpec;
 
@@ -7202,7 +7207,7 @@ Sema::ComputeDefaultedDtorExceptionSpec(CXXRecordDecl *ClassDecl) {
       continue;
     
     if (const RecordType *BaseType = B->getType()->getAs<RecordType>())
-      ExceptSpec.CalledDecl(
+      ExceptSpec.CalledDecl(B->getLocStart(),
                    LookupDestructor(cast<CXXRecordDecl>(BaseType->getDecl())));
   }
 
@@ -7211,7 +7216,7 @@ Sema::ComputeDefaultedDtorExceptionSpec(CXXRecordDecl *ClassDecl) {
                                        BEnd = ClassDecl->vbases_end();
        B != BEnd; ++B) {
     if (const RecordType *BaseType = B->getType()->getAs<RecordType>())
-      ExceptSpec.CalledDecl(
+      ExceptSpec.CalledDecl(B->getLocStart(),
                   LookupDestructor(cast<CXXRecordDecl>(BaseType->getDecl())));
   }
 
@@ -7221,7 +7226,7 @@ Sema::ComputeDefaultedDtorExceptionSpec(CXXRecordDecl *ClassDecl) {
        F != FEnd; ++F) {
     if (const RecordType *RecordTy
         = Context.getBaseElementType(F->getType())->getAs<RecordType>())
-      ExceptSpec.CalledDecl(
+      ExceptSpec.CalledDecl(F->getLocation(),
                   LookupDestructor(cast<CXXRecordDecl>(RecordTy->getDecl())));
   }
 
@@ -7546,7 +7551,7 @@ std::pair<Sema::ImplicitExceptionSpecification, bool>