https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66260
Bug ID: 66260
Summary: [C++14] Failure to compile variable template with
recursively defined partial specialization
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: Casey at Carter dot net
Target Milestone: ---
Created attachment 35604
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35604&action=edit
testcase.cpp
Both GCC 5.1.0 and 6.0 fail to compile this program:
template <class>
constexpr bool foo = false;
template <>
constexpr bool foo<int> = true;
template <class T, int N>
constexpr bool foo<T[N]> = foo<T>;
static_assert(foo<int>, "");
static_assert(!foo<double>, "");
static_assert(foo<int[3]>, "");
static_assert(!foo<double[3]>, "");
static_assert(foo<int[2][5][3]>, "");
static_assert(!foo<double[2][5][3]>, "");
int main() {}
5.1.0 doesn't seem to recognize that foo is a template-name in the definition
of the foo<T[N]> partial specialization:
prog.cc:6:33: error: expected primary-expression before '>' token
constexpr bool foo<T[N]> = foo<T>;
^
prog.cc:6:34: error: expected primary-expression before ';' token
constexpr bool foo<T[N]> = foo<T>;
^
prog.cc:6: confused by earlier errors, bailing out
6.0 20150522 at least tries to compile the recursion, but fails nonetheless:
prog.cc: In instantiation of 'constexpr const bool foo':
prog.cc:6:16: recursively required from 'constexpr const bool foo'
prog.cc:6:16: required from 'constexpr const bool foo'
prog.cc:10:15: required from here
prog.cc:6:16: fatal error: template instantiation depth exceeds maximum of 900
(use -ftemplate-depth= to increase the maximum)
constexpr bool foo<T[N]> = foo<T>;
^
compilation terminated.
