https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86346
Bug ID: 86346
Summary: internal compiler error related to duduction guides
Product: gcc
Version: 8.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: vanyacpp at gmail dot com
Target Milestone: ---
Here is the code:
template<bool>
struct bool_constant {};
using true_type = bool_constant<true>;
template<typename, typename>
constexpr bool is_same_v = false;
template<typename T>
constexpr bool is_same_v<T, T> = true;
template<typename T>
struct vector
{
template<typename U>
static constexpr bool v = is_same_v<T, bool> || false;
vector(bool_constant<v<T>>, T); // (1)
};
template<>
struct vector<bool> // (2)
{
vector(true_type, bool);
};
vector v { true_type{}, false }; // (3)
The problem is that the deduction guide generated from the constructor (1)
refers to a member v of the primary template. At (3) T is then deduced to be
bool, but substitution T->bool should never be used for primary template, as
there is explicit specialization vector<bool> (2).
Clang gives an error on this code "note: candidate template ignored:
substitution failure [with T = bool]: cannot reference member of primary
template because deduced class template specialization 'vector<bool>' is an
explicit specialization".
I believe GCC should provide a similar message in this case instead of
crashing.
