[Bug libstdc++/69266] bootstrap failure undefined reference to `std::basic_ios<char, std::char_traits<char> >::

["irfanadilovic at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69266

Irfan Adilovic <irfanadilovic at gmail dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |irfanadilovic at gmail dot com

--- Comment #5 from Irfan Adilovic <irfanadilovic at gmail dot com> ---
I can confirm that this still happens with the 20160117 snapshot. I've tried
tprince's suggestion to --disable-libstdcxx but this first leads to a
-Werror=pedantic error in isl/include/isl/ctx.h:83 due to a trailing comma in

typedef enum {
    isl_stat_error = -1,
    isl_stat_ok = 0, // <-- here
} isl_stat;

ISL was downloaded via contrib/download_prerequisites. Fixing that leads to a
make error when "Comparing stages 2 and 3":

Comparing stages 2 and 3
warning: gcc/cc1-checksum.o differs
warning: gcc/cc1plus-checksum.o differs
Bootstrap comparison failure!
gmp/mpf/eq.o differs
... about 60 such lines
gmp/randmui.o differs
Makefile:20907: recipe for target 'compare' failed

Is there a snapshot known to have worked on cygwin to perform a bisect?