https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79316
Bug ID: 79316
Summary: Default parameter values in explicit deduction guides
do not work
Product: gcc
Version: 7.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mike at spertus dot com
Target Milestone: ---
When I compile the following code with gcc-7-20170122,
template<typename T> struct S { S(T t) {} };
template<typename T> S(T, int = 7) -> S<T>;
I get the following error
error: default arguments are only permitted for function parameters
[-fpermissive]
I believe that the above code should be correct as deduction-guides accept a
parameter-declaration-clause, which can have default argument values. In
addition, P0433R0 contains examples of deduction guides with default arguments
(e.g., for deque).
