[Bug c++/112867] [11/12/13/14 Regression] extern function declaration inside a generic (templated) lambda inside a template function goes wrong

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112867

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
This worked in GCC 7.  GCC 8 started ICEing with r8-2720-gf44a8dd56f5bfb

commit f44a8dd56f5bfbd0596c39693e268ef880c06221
Author: Jason Merrill <jason@redhat.com>
Date:   Tue Aug 29 16:37:15 2017 -0400

    Reimplement handling of lambdas in templates.

Then, the ICE was fixed by r11-3192 and the test compiled fine again:

commit e9fdb9a73249f95f3da2d7fde6f268ae12d0d22c
Author: Nathan Sidwell <nathan@acm.org>
Date:   Mon Sep 14 09:42:29 2020 -0700

    c++: local externs in templates do not get template head

and then with r11-3699:

commit 4e62aca0e0520e4ed2532f2d8153581190621c1a
Author: Nathan Sidwell <nathan@acm.org>
Date:   Wed Oct 7 05:46:24 2020 -0700

    c++: block-scope externs get an alias [PR95677,PR31775,PR95677]

the error appeared.