PR c++/68290
* constraint.cc (make_constrained_auto): Move to...
* pt.c (make_auto_1): Add set_canonical parameter and set
TYPE_CANONICAL on the type only if it is true.
(make_decltype_auto): Adjust call to make_auto_1.
(make_auto): Likewise.
(splice_late_return_type): Likewise.
(make_constrained_auto): ...here. Call make_auto_1 instead of
make_auto and pass false. Set TYPE_CANONICAL directly.