[Bug libstdc++/85843] warning: base class ‘class std::exception’ should be explicitly initialized in the copy constructor [-Wextra]

[sgk at troutmask dot apl.washington.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85843

--- Comment #5 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Sun, May 20, 2018 at 07:27:28PM +0000, redi at gcc dot gnu.org wrote:
> 
> --- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
> i.e. there's no invalid C++ at all, you're just asking for all warnings to
> break your build.
> 

% cd gcc/
% svn update
% cd ../obj
% rm -rf *
% cat ../conf
#! /bin/sh

CC=/usr/local/bin/gcc7
export CC

CXX=/usr/local/bin/g++7
export CXX

../gcc/configure --prefix=$HOME/work/x --enable-languages=c,fortran \
  --enable-bootstrap --disable-nls --enable-checking=yes \
  --enable-maintainer-mode
% ../conf
% gmake -j7 bootstrap
<boom>

Boostrap is broken. 
Waste a day trying to identify issue.

Ergo P1.