Introduce the notion of instantiation dependence into Clang's AST. A

type/expression/template argument/etc. is instantiation-dependent if
it somehow involves a template parameter, even if it doesn't meet the
requirements for the more common kinds of dependence (dependent type,
type-dependent expression, value-dependent expression).

When we see an instantiation-dependent type, we know we always need to
perform substitution into that instantiation-dependent type. This
keeps us from short-circuiting evaluation in places where we
shouldn't, and lets us properly implement C++0x [temp.type]p2.

In theory, this would also allow us to properly mangle
instantiation-dependent-but-not-dependent decltype types per the
Itanium C++ ABI, but we aren't quite there because we still mangle
based on the canonical type in cases like, e.g.,

  template<unsigned> struct A { };
  template<typename T>
    void f(A<sizeof(sizeof(decltype(T() + T())))>) { }
  template void f<int>(A<sizeof(sizeof(int))>);

and therefore get the wrong answer.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@134225 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 14 insertions, 10 deletions

diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index d88b785762..a7034aa771 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -1898,6 +1898,7 @@ QualType Sema::CheckTemplateIdType(TemplateName Name,
 
   QualType CanonType;
 
+  bool InstantiationDependent = false;
   if (TypeAliasTemplateDecl *AliasTemplate
         = dyn_cast<TypeAliasTemplateDecl>(Template)) {
     // Find the canonical type for this type alias template specialization.
@@ -1923,7 +1924,7 @@ QualType Sema::CheckTemplateIdType(TemplateName Name,
       return QualType();
   } else if (Name.isDependent() ||
              TemplateSpecializationType::anyDependentTemplateArguments(
-               TemplateArgs)) {
+               TemplateArgs, InstantiationDependent)) {
     // This class template specialization is a dependent
     // type. Therefore, its canonical type is another class template
     // specialization type that contains all of the converted
@@ -4833,10 +4834,12 @@ Sema::ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec,
                                          Converted))
       return true;
 
+    bool InstantiationDependent;
     if (!Name.isDependent() &&
         !TemplateSpecializationType::anyDependentTemplateArguments(
                                              TemplateArgs.getArgumentArray(),
-                                                         TemplateArgs.size())) {
+                                                         TemplateArgs.size(),
+                                                     InstantiationDependent)) {
       Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
         << ClassTemplate->getDeclName();
       isPartialSpecialization = false;
diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index c452e26a40..675cef7986 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -807,7 +807,7 @@ bool TemplateInstantiator::AlreadyTransformed(QualType T) {
   if (T.isNull())
     return true;
   
-  if (T->isDependentType() || T->isVariablyModifiedType())
+  if (T->isInstantiationDependentType() || T->isVariablyModifiedType())
     return false;
   
   getSema().MarkDeclarationsReferencedInType(Loc, T);
@@ -1340,7 +1340,7 @@ TypeSourceInfo *Sema::SubstType(TypeSourceInfo *T,
          "Cannot perform an instantiation without some context on the "
          "instantiation stack");
   
-  if (!T->getType()->isDependentType() && 
+  if (!T->getType()->isInstantiationDependentType() && 
       !T->getType()->isVariablyModifiedType())
     return T;
 
@@ -1359,7 +1359,7 @@ TypeSourceInfo *Sema::SubstType(TypeLoc TL,
   if (TL.getType().isNull())
     return 0;
 
-  if (!TL.getType()->isDependentType() && 
+  if (!TL.getType()->isInstantiationDependentType() && 
       !TL.getType()->isVariablyModifiedType()) {
     // FIXME: Make a copy of the TypeLoc data here, so that we can
     // return a new TypeSourceInfo. Inefficient!
@@ -1388,7 +1388,7 @@ QualType Sema::SubstType(QualType T,
 
   // If T is not a dependent type or a variably-modified type, there
   // is nothing to do.
-  if (!T->isDependentType() && !T->isVariablyModifiedType())
+  if (!T->isInstantiationDependentType() && !T->isVariablyModifiedType())
     return T;
 
   TemplateInstantiator Instantiator(*this, TemplateArgs, Loc, Entity);
@@ -1396,7 +1396,8 @@ QualType Sema::SubstType(QualType T,
 }
 
 static bool NeedsInstantiationAsFunctionType(TypeSourceInfo *T) {
-  if (T->getType()->isDependentType() || T->getType()->isVariablyModifiedType())
+  if (T->getType()->isInstantiationDependentType() || 
+      T->getType()->isVariablyModifiedType())
     return true;
 
   TypeLoc TL = T->getTypeLoc().IgnoreParens();
@@ -1410,7 +1411,7 @@ static bool NeedsInstantiationAsFunctionType(TypeSourceInfo *T) {
     // The parameter's type as written might be dependent even if the
     // decayed type was not dependent.
     if (TypeSourceInfo *TSInfo = P->getTypeSourceInfo())
-      if (TSInfo->getType()->isDependentType())
+      if (TSInfo->getType()->isInstantiationDependentType())
         return true;
 
     // TODO: currently we always rebuild expressions.  When we
diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 196e847728..b6d5abfcc8 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -132,7 +132,7 @@ Decl *TemplateDeclInstantiator::InstantiateTypedefNameDecl(TypedefNameDecl *D,
                                                            bool IsTypeAlias) {
   bool Invalid = false;
   TypeSourceInfo *DI = D->getTypeSourceInfo();
-  if (DI->getType()->isDependentType() ||
+  if (DI->getType()->isInstantiationDependentType() ||
       DI->getType()->isVariablyModifiedType()) {
     DI = SemaRef.SubstType(DI, TemplateArgs,
                            D->getLocation(), D->getDeclName());
@@ -435,7 +435,7 @@ Decl *TemplateDeclInstantiator::VisitAccessSpecDecl(AccessSpecDecl *D) {
 Decl *TemplateDeclInstantiator::VisitFieldDecl(FieldDecl *D) {
   bool Invalid = false;
   TypeSourceInfo *DI = D->getTypeSourceInfo();
-  if (DI->getType()->isDependentType() ||
+  if (DI->getType()->isInstantiationDependentType() ||
       DI->getType()->isVariablyModifiedType())  {
     DI = SemaRef.SubstType(DI, TemplateArgs,
                            D->getLocation(), D->getDeclName());