https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65708
Bug ID: 65708
Summary: Non-type template argument not visible causes
substitution failure
Product: gcc
Version: 5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ldionne.2 at gmail dot com
The following code produces an error on GCC trunk. The error says that there
is no matching `f` to call:
------------------------------------------------------------------------------
template <typename T, T v>
struct integral_constant { };
template <typename T, T v>
decltype(~v) f(integral_constant<T, v>);
int main() {
f(integral_constant<int, 6>{});
}
------------------------------------------------------------------------------
Even more curious is that the problem goes away if I replace `decltype(~v)`
by `decltype(v)` or even `decltype(+v)`.
The exact error is:
› ~/code/gcc5/bin/g++ ~/code/hana/test/worksheet.cpp -std=c++11
[...]: In function ‘int main()’:
[...]: error: no matching function for call to ‘f(integral_constant<int, 6>)’
f(integral_constant<int, 6>{});
^
[...]: note: candidate: template<class T, T v> decltype (~ v)
f(integral_constant<T, v>)
decltype(~v) f(integral_constant<T, v>);
^
[...]: note: template argument deduction/substitution failed:
[...]: In substitution of ‘template<class T, T v> decltype (~ v)
f(integral_constant<T, v>) [with T = int; T v = 6]’:
[...]: required from here
[...]: error: ‘v’ was not declared in this scope
My GCC version:
› ~/code/gcc5/bin/g++ --version
g++ (GCC) 5.0.0 20150326 (experimental)
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