Rework the way we track which declarations are "used" during

compilation, and (hopefully) introduce RAII objects for changing the
"potentially evaluated" state at all of the necessary places within
Sema and Parser. Other changes:

  - Set the unevaluated/potentially-evaluated context appropriately
    during template instantiation.
  - We now recognize three different states while parsing or
    instantiating expressions: unevaluated, potentially evaluated, and
    potentially potentially evaluated (for C++'s typeid).
  - When we're in a potentially potentially-evaluated context, queue
    up MarkDeclarationReferenced calls in a stack. For C++ typeid
    expressions that are potentially evaluated, we will play back
    these MarkDeclarationReferenced calls when we exit the
    corresponding potentially potentially-evaluated context.
  - Non-type template arguments are now parsed as constant
    expressions, so they are not potentially-evaluated.

llvm-svn: 73899

1 files changed, 11 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 3992f8cbe53..1c4e907d4d6 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -420,6 +420,7 @@ InstantiateDependentSizedArrayType(const DependentSizedArrayType *T,
   }
   
   // Instantiate the size expression
+  EnterExpressionEvaluationContext Unevaluated(SemaRef, Action::Unevaluated);
   Sema::OwningExprResult InstantiatedArraySize = 
     SemaRef.InstantiateExpr(ArraySize, TemplateArgs);
   if (InstantiatedArraySize.isInvalid())
@@ -443,6 +444,10 @@ InstantiateDependentSizedExtVectorType(const DependentSizedExtVectorType *T,
       return QualType();
   }
 
+  // The expression in a dependent-sized extended vector type is not
+  // potentially evaluated.
+  EnterExpressionEvaluationContext Unevaluated(SemaRef, Action::Unevaluated);
+
   // Instantiate the size expression.
   const Expr *SizeExpr = T->getSizeExpr();
   Sema::OwningExprResult InstantiatedArraySize = 
@@ -520,6 +525,9 @@ TemplateTypeInstantiator::InstantiateTypedefType(const TypedefType *T,
 QualType 
 TemplateTypeInstantiator::InstantiateTypeOfExprType(const TypeOfExprType *T,
                                                     unsigned Quals) const {
+  // The expression in a typeof is not potentially evaluated.
+  EnterExpressionEvaluationContext Unevaluated(SemaRef, Action::Unevaluated);
+  
   Sema::OwningExprResult E 
     = SemaRef.InstantiateExpr(T->getUnderlyingExpr(), TemplateArgs);
   if (E.isInvalid())
@@ -1175,6 +1183,9 @@ TemplateArgument Sema::Instantiate(TemplateArgument Arg,
     return Arg;
 
   case TemplateArgument::Expression: {
+    // Template argument expressions are not potentially evaluated.
+    EnterExpressionEvaluationContext Unevaluated(*this, Action::Unevaluated);
+
     Sema::OwningExprResult E = InstantiateExpr(Arg.getAsExpr(), TemplateArgs);
     if (E.isInvalid())
       return TemplateArgument();