rsmith added inline comments.
================
Comment at: lib/Sema/SemaTemplateInstantiateDecl.cpp:3861
@@ -3860,3 +3860,3 @@
// static data members until a definition of the variable is needed. We need
- // it right away if the type contains 'auto'.
+ // it right away if the type contains 'auto' or is an IncompleteArrayType.
if ((!isa<VarTemplateSpecializationDecl>(NewVar) &&
----------------
I don't see why we would need the initializer right away in the
`IncompleteArrayType` case. It seems instead that we should delay instantiation
of the initializer until a complete type is required for the variable
(`Sema::RequireCompleteExprType` handles this case) or it is used in a context
that requires a definition (`Sema::MarkVariableReferenced` handles this case).
You can reproduce a related bug in C++11 mode like so:
template<typename T> struct X { static const int arr[]; };
template<typename T> constexpr int X<T>::arr[] = {1, 2, 3};
constexpr int k = X<int>::arr[0];
or:
template<typename T> struct X { static const double n; };
template<typename T> constexpr double X<T>::n = 1;
template<int> struct Y {};
Y<(int)X<int>::n> y;
It looks like the bug in this case is that
`VarDecl::isUsableInConstantExpressions` (called from
`DoMarkVarDeclReferenced`) is mishandling this case: once it's determined that
the variable is of non-`volatile` `const`-qualified type, it needs to map back
to the template instantiation pattern and check whether the most recent
declaration of that is declared `constexpr`, since there might be a
not-yet-instantiated redeclaration that adds the `constexpr`.
I'm not sure that's the same bug you're hitting here, though, since in this
case we should be instantiating the `constexpr` specifier with the initial
declaration, which should be enough to cause `isUsableInConstantExpressions` to
return `true`. So the mystery is, why is `DoMarkVarDeclReferenced` not
triggering instantiation?
http://reviews.llvm.org/D22053
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
