Don't treat a non-deduced 'auto' type as being type-dependent. Instead, there

are now two distinct canonical 'AutoType's: one is the undeduced 'auto'
placeholder type, and the other is a deduced-but-dependent type. All
deduced-to-a-non-dependent-type cases are still non-canonical.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180789 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 107 insertions, 105 deletions

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 9a3499dc39..1e5e5bb259 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2798,8 +2798,7 @@ void Sema::MergeVarDeclTypes(VarDecl *New, VarDecl *Old, bool OldWasHidden) {
 
   QualType MergedT;
   if (getLangOpts().CPlusPlus) {
-    AutoType *AT = New->getType()->getContainedAutoType();
-    if (AT && !AT->isDeduced()) {
+    if (New->getType()->isUndeducedType()) {
       // We don't know what the new type is until the initializer is attached.
       return;
     } else if (Context.hasSameType(New->getType(), Old->getType())) {
@@ -5142,27 +5141,18 @@ static bool mayConflictWithNonVisibleExternC(const T *ND) {
   return ND->isExternC();
 }
 
-/// \brief Perform semantic checking on a newly-created variable
-/// declaration.
-///
-/// This routine performs all of the type-checking required for a
-/// variable declaration once it has been built. It is used both to
-/// check variables after they have been parsed and their declarators
-/// have been translated into a declaration, and to check variables
-/// that have been instantiated from a template.
-///
-/// Sets NewVD->isInvalidDecl() if an error was encountered.
-///
-/// Returns true if the variable declaration is a redeclaration.
-bool Sema::CheckVariableDeclaration(VarDecl *NewVD,
-                                    LookupResult &Previous) {
+void Sema::CheckVariableDeclarationType(VarDecl *NewVD) {
   // If the decl is already known invalid, don't check it.
   if (NewVD->isInvalidDecl())
-    return false;
+    return;
 
   TypeSourceInfo *TInfo = NewVD->getTypeSourceInfo();
   QualType T = TInfo->getType();
 
+  // Defer checking an 'auto' type until its initializer is attached.
+  if (T->isUndeducedType())
+    return;
+
   if (T->isObjCObjectType()) {
     Diag(NewVD->getLocation(), diag::err_statically_allocated_object)
       << FixItHint::CreateInsertion(NewVD->getLocation(), "*");
@@ -5177,7 +5167,7 @@ bool Sema::CheckVariableDeclaration(VarDecl *NewVD,
   if (NewVD->hasLocalStorage() && T.getAddressSpace() != 0) {
     Diag(NewVD->getLocation(), diag::err_as_qualified_auto_decl);
     NewVD->setInvalidDecl();
-    return false;
+    return;
   }
 
   // OpenCL v1.2 s6.5 - All program scope variables must be declared in the
@@ -5187,7 +5177,7 @@ bool Sema::CheckVariableDeclaration(VarDecl *NewVD,
       && !T->isSamplerT()){
     Diag(NewVD->getLocation(), diag::err_opencl_global_invalid_addr_space);
     NewVD->setInvalidDecl();
-    return false;
+    return;
   }
   
   // OpenCL v1.2 s6.8 -- The static qualifier is valid only in program
@@ -5196,7 +5186,7 @@ bool Sema::CheckVariableDeclaration(VarDecl *NewVD,
       && NewVD->isStaticLocal()) {
     Diag(NewVD->getLocation(), diag::err_static_function_scope);
     NewVD->setInvalidDecl();
-    return false;
+    return;
   }
 
   if (NewVD->hasLocalStorage() && T.isObjCGCWeak()
@@ -5237,7 +5227,7 @@ bool Sema::CheckVariableDeclaration(VarDecl *NewVD,
         Diag(NewVD->getLocation(), diag::err_vla_decl_has_extern_linkage)
         << SizeRange;
       NewVD->setInvalidDecl();
-      return false;
+      return;
     }
 
     if (FixedTInfo == 0) {
@@ -5246,7 +5236,7 @@ bool Sema::CheckVariableDeclaration(VarDecl *NewVD,
       else
         Diag(NewVD->getLocation(), diag::err_vm_decl_has_extern_linkage);
       NewVD->setInvalidDecl();
-      return false;
+      return;
     }
 
     Diag(NewVD->getLocation(), diag::warn_illegal_constant_array_size);
@@ -5254,6 +5244,54 @@ bool Sema::CheckVariableDeclaration(VarDecl *NewVD,
     NewVD->setTypeSourceInfo(FixedTInfo);
   }
 
+  if (T->isVoidType() && NewVD->isThisDeclarationADefinition()) {
+    Diag(NewVD->getLocation(), diag::err_typecheck_decl_incomplete_type)
+      << T;
+    NewVD->setInvalidDecl();
+    return;
+  }
+
+  if (!NewVD->hasLocalStorage() && NewVD->hasAttr<BlocksAttr>()) {
+    Diag(NewVD->getLocation(), diag::err_block_on_nonlocal);
+    NewVD->setInvalidDecl();
+    return;
+  }
+
+  if (isVM && NewVD->hasAttr<BlocksAttr>()) {
+    Diag(NewVD->getLocation(), diag::err_block_on_vm);
+    NewVD->setInvalidDecl();
+    return;
+  }
+
+  if (NewVD->isConstexpr() && !T->isDependentType() &&
+      RequireLiteralType(NewVD->getLocation(), T,
+                         diag::err_constexpr_var_non_literal)) {
+    // Can't perform this check until the type is deduced.
+    NewVD->setInvalidDecl();
+    return;
+  }
+}
+
+/// \brief Perform semantic checking on a newly-created variable
+/// declaration.
+///
+/// This routine performs all of the type-checking required for a
+/// variable declaration once it has been built. It is used both to
+/// check variables after they have been parsed and their declarators
+/// have been translated into a declaration, and to check variables
+/// that have been instantiated from a template.
+///
+/// Sets NewVD->isInvalidDecl() if an error was encountered.
+///
+/// Returns true if the variable declaration is a redeclaration.
+bool Sema::CheckVariableDeclaration(VarDecl *NewVD,
+                                    LookupResult &Previous) {
+  CheckVariableDeclarationType(NewVD);
+
+  // If the decl is already known invalid, don't check it.
+  if (NewVD->isInvalidDecl())
+    return false;
+
   // If we did not find anything by this name, look for a non-visible
   // extern "C" declaration with the same name.
   //
@@ -5292,32 +5330,6 @@ bool Sema::CheckVariableDeclaration(VarDecl *NewVD,
   // Filter out any non-conflicting previous declarations.
   filterNonConflictingPreviousDecls(Context, NewVD, Previous);
 
-  if (T->isVoidType() && NewVD->isThisDeclarationADefinition()) {
-    Diag(NewVD->getLocation(), diag::err_typecheck_decl_incomplete_type)
-      << T;
-    NewVD->setInvalidDecl();
-    return false;
-  }
-
-  if (!NewVD->hasLocalStorage() && NewVD->hasAttr<BlocksAttr>()) {
-    Diag(NewVD->getLocation(), diag::err_block_on_nonlocal);
-    NewVD->setInvalidDecl();
-    return false;
-  }
-
-  if (isVM && NewVD->hasAttr<BlocksAttr>()) {
-    Diag(NewVD->getLocation(), diag::err_block_on_vm);
-    NewVD->setInvalidDecl();
-    return false;
-  }
-
-  if (NewVD->isConstexpr() && !T->isDependentType() &&
-      RequireLiteralType(NewVD->getLocation(), T,
-                         diag::err_constexpr_var_non_literal)) {
-    NewVD->setInvalidDecl();
-    return false;
-  }
-
   if (!Previous.empty()) {
     MergeVarDecl(NewVD, Previous, PreviousWasHidden);
     return true;
@@ -7284,10 +7296,7 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
   ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
 
   // C++11 [decl.spec.auto]p6. Deduce the type which 'auto' stands in for.
-  AutoType *Auto = 0;
-  if (TypeMayContainAuto &&
-      (Auto = VDecl->getType()->getContainedAutoType()) &&
-      !Auto->isDeduced()) {
+  if (TypeMayContainAuto && VDecl->getType()->isUndeducedType()) {
     Expr *DeduceInit = Init;
     // Initializer could be a C++ direct-initializer. Deduction only works if it
     // contains exactly one expression.
@@ -7357,6 +7366,11 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
     // the previously declared type.
     if (VarDecl *Old = VDecl->getPreviousDecl())
       MergeVarDeclTypes(VDecl, Old, /*OldWasHidden*/ false);
+
+    // Check the deduced type is valid for a variable declaration.
+    CheckVariableDeclarationType(VDecl);
+    if (VDecl->isInvalidDecl())
+      return;
   }
 
   if (VDecl->isLocalVarDecl() && VDecl->hasExternalStorage()) {
@@ -8190,8 +8204,8 @@ Sema::BuildDeclaratorGroup(Decl **Group, unsigned NumDecls,
         // Don't reissue diagnostics when instantiating a template.
         if (AT && D->isInvalidDecl())
           break;
-        if (AT && AT->isDeduced()) {
-          QualType U = AT->getDeducedType();
+        QualType U = AT ? AT->getDeducedType() : QualType();
+        if (!U.isNull()) {
           CanQualType UCanon = Context.getCanonicalType(U);
           if (Deduced.isNull()) {
             Deduced = U;
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index c05d29d7d4..df09b4bcae 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -1118,9 +1118,7 @@ Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
     HaveCompleteInit = true;
 
   // C++11 [decl.spec.auto]p6. Deduce the type which 'auto' stands in for.
-  AutoType *AT = 0;
-  if (TypeMayContainAuto &&
-      (AT = AllocType->getContainedAutoType()) && !AT->isDeduced()) {
+  if (TypeMayContainAuto && AllocType->isUndeducedType()) {
     if (initStyle == CXXNewExpr::NoInit || NumInits == 0)
       return ExprError(Diag(StartLoc, diag::err_auto_new_requires_ctor_arg)
                        << AllocType << TypeRange);
@@ -2279,6 +2277,9 @@ Sema::ActOnCXXDelete(SourceLocation StartLoc, bool UseGlobal,
 ExprResult Sema::CheckConditionVariable(VarDecl *ConditionVar,
                                         SourceLocation StmtLoc,
                                         bool ConvertToBoolean) {
+  if (ConditionVar->isInvalidDecl())
+    return ExprError();
+
   QualType T = ConditionVar->getType();
 
   // C++ [stmt.select]p2:
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index eab2d81f39..85a74490cb 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -2087,6 +2087,10 @@ addAssociatedClassesAndNamespaces(AssociatedLookup &Result, QualType Ty) {
     case Type::Complex:
       break;
 
+    // Non-deduced auto types only get here for error cases.
+    case Type::Auto:
+      break;
+
     // If T is an Objective-C object or interface type, or a pointer to an 
     // object or interface type, the associated namespace is the global
     // namespace.
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index 4fc1818d32..63c2a7d8e6 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -1923,7 +1923,15 @@ Sema::BuildCXXForRangeStmt(SourceLocation ForLoc, SourceLocation ColonLoc,
   StmtResult BeginEndDecl = BeginEnd;
   ExprResult NotEqExpr = Cond, IncrExpr = Inc;
 
-  if (!BeginEndDecl.get() && !RangeVarType->isDependentType()) {
+  if (RangeVarType->isDependentType()) {
+    // The range is implicitly used as a placeholder when it is dependent.
+    RangeVar->setUsed();
+
+    // Deduce any 'auto's in the loop variable as 'DependentTy'. We'll fill
+    // them in properly when we instantiate the loop.
+    if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check)
+      LoopVar->setType(SubstAutoType(LoopVar->getType(), Context.DependentTy));
+  } else if (!BeginEndDecl.get()) {
     SourceLocation RangeLoc = RangeVar->getLocation();
 
     const QualType RangeVarNonRefType = RangeVarType.getNonReferenceType();
@@ -2110,9 +2118,6 @@ Sema::BuildCXXForRangeStmt(SourceLocation ForLoc, SourceLocation ColonLoc,
       if (LoopVar->isInvalidDecl())
         NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
     }
-  } else {
-    // The range is implicitly used as a placeholder when it is dependent.
-    RangeVar->setUsed();
   }
 
   // Don't bother to actually allocate the result if we're just trying to
diff --git a/lib/Sema/SemaTemplateDeduction.cpp b/lib/Sema/SemaTemplateDeduction.cpp
index a681371c9b..ea5b145871 100644
--- a/lib/Sema/SemaTemplateDeduction.cpp
+++ b/lib/Sema/SemaTemplateDeduction.cpp
@@ -3584,8 +3584,12 @@ namespace {
         NewTL.setNameLoc(TL.getNameLoc());
         return Result;
       } else {
-        QualType Result = RebuildAutoType(Replacement,
-                                          TL.getTypePtr()->isDecltypeAuto());
+        bool Dependent =
+          !Replacement.isNull() && Replacement->isDependentType();
+        QualType Result =
+          SemaRef.Context.getAutoType(Dependent ? QualType() : Replacement,
+                                      TL.getTypePtr()->isDecltypeAuto(),
+                                      Dependent);
         AutoTypeLoc NewTL = TLB.push<AutoTypeLoc>(Result);
         NewTL.setNameLoc(TL.getNameLoc());
         return Result;
@@ -3597,41 +3601,6 @@ namespace {
       return E;
     }
   };
-
-  /// Determine whether the specified type (which contains an 'auto' type
-  /// specifier) is dependent. This is not trivial, because the 'auto' specifier
-  /// itself claims to be type-dependent.
-  bool isDependentAutoType(QualType Ty) {
-    while (1) {
-      QualType Pointee = Ty->getPointeeType();
-      if (!Pointee.isNull()) {
-        Ty = Pointee;
-      } else if (const MemberPointerType *MPT = Ty->getAs<MemberPointerType>()){
-        if (MPT->getClass()->isDependentType())
-          return true;
-        Ty = MPT->getPointeeType();
-      } else if (const FunctionProtoType *FPT = Ty->getAs<FunctionProtoType>()){
-        for (FunctionProtoType::arg_type_iterator I = FPT->arg_type_begin(),
-                                                  E = FPT->arg_type_end();
-             I != E; ++I)
-          if ((*I)->isDependentType())
-            return true;
-        Ty = FPT->getResultType();
-      } else if (Ty->isDependentSizedArrayType()) {
-        return true;
-      } else if (const ArrayType *AT = Ty->getAsArrayTypeUnsafe()) {
-        Ty = AT->getElementType();
-      } else if (Ty->getAs<DependentSizedExtVectorType>()) {
-        return true;
-      } else if (const VectorType *VT = Ty->getAs<VectorType>()) {
-        Ty = VT->getElementType();
-      } else {
-        break;
-      }
-    }
-    assert(Ty->getAs<AutoType>() && "didn't find 'auto' in auto type");
-    return false;
-  }
 }
 
 /// \brief Deduce the type for an auto type-specifier (C++0x [dcl.spec.auto]p6)
@@ -3654,8 +3623,9 @@ Sema::DeduceAutoType(TypeSourceInfo *Type, Expr *&Init,
     Init = result.take();
   }
 
-  if (Init->isTypeDependent() || isDependentAutoType(Type->getType())) {
-    Result = Type;
+  if (Init->isTypeDependent() || Type->getType()->isDependentType()) {
+    Result =
+        SubstituteAutoTransform(*this, Context.DependentTy).TransformType(Type);
     return DAR_Succeeded;
   }
 
@@ -3749,6 +3719,10 @@ Sema::DeduceAutoType(TypeSourceInfo *Type, Expr *&Init,
   return DAR_Succeeded;
 }
 
+QualType Sema::SubstAutoType(QualType Type, QualType Deduced) {
+  return SubstituteAutoTransform(*this, Deduced).TransformType(Type);
+}
+
 void Sema::DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init) {
   if (isa<InitListExpr>(Init))
     Diag(VDecl->getLocation(),
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 8bf5143bed..7ed16878db 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -2569,11 +2569,11 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
 
       if (const AutoType *AT = T->getContainedAutoType()) {
         // We've already diagnosed this for decltype(auto).
-        if (!AT->isDecltypeAuto()) {
+        if (!AT->isDecltypeAuto())
           S.Diag(DeclType.Loc, diag::err_illegal_decl_array_of_auto)
             << getPrintableNameForEntity(Name) << T;
-          D.setInvalidType(true);
-        }
+        T = QualType();
+        break;
       }
 
       T = S.BuildArrayType(T, ASM, ArraySize, ATI.TypeQuals,
@@ -3831,7 +3831,7 @@ static bool handleObjCOwnershipTypeAttr(TypeProcessingState &state,
                                        QualType &type) {
   bool NonObjCPointer = false;
 
-  if (!type->isDependentType()) {
+  if (!type->isDependentType() && !type->isUndeducedType()) {
     if (const PointerType *ptr = type->getAs<PointerType>()) {
       QualType pointee = ptr->getPointeeType();
       if (pointee->isObjCRetainableType() || pointee->isPointerType())
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index c0bc34fa97..925860a600 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -764,6 +764,9 @@ public:
   ///
   /// By default, builds a new AutoType with the given deduced type.
   QualType RebuildAutoType(QualType Deduced, bool IsDecltypeAuto) {
+    // Note, IsDependent is always false here: we implicitly convert an 'auto'
+    // which has been deduced to a dependent type into an undeduced 'auto', so
+    // that we'll retry deduction after the transformation.
     return SemaRef.Context.getAutoType(Deduced, IsDecltypeAuto);
   }
 
@@ -4500,7 +4503,8 @@ QualType TreeTransform<Derived>::TransformAutoType(TypeLocBuilder &TLB,
   }
 
   QualType Result = TL.getType();
-  if (getDerived().AlwaysRebuild() || NewDeduced != OldDeduced) {
+  if (getDerived().AlwaysRebuild() || NewDeduced != OldDeduced ||
+      T->isDependentType()) {
     Result = getDerived().RebuildAutoType(NewDeduced, T->isDecltypeAuto());
     if (Result.isNull())
       return QualType();