[Bug c++/71285] New: [7 regression] spurious 'insufficient contextual information' for member access on fold expression

[lucdanton at free dot fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71285

            Bug ID: 71285
           Summary: [7 regression] spurious 'insufficient contextual
                    information' for member access on fold expression
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: lucdanton at free dot fr
  Target Milestone: ---

On rev. 236761 it looks like performing member access on a fold expression
produces an 'insufficient contextual information to determine type' error, even
before instantiation.

Example:

$ cat main.cpp
template<typename... Args>
void spurious(Args... args)
{
    (... + args).member;
}

int main()
{
}
$ g++-trunk -std=c++1z main.cpp
main.cpp: In function 'void spurious(Args ...)':
main.cpp:4:17: error: insufficient contextual information to determine type
     (... + args).member;
                 ^