Ok, so it seems, that the latest glibc update was made to fix the icu4c
thing.
It just broke the locales.
Fix for that has just been pushed, making core-updates usable again.
I pushed to my icedtea branch also.
I'm now building it to see what we have now.

2017-12-04 13:59 GMT+01:00 Gábor Boskovits <boskovits@gmail.com>:

> Upstream corrected the issue in commit 6913ad65e00bb32417ad39c41d292b
> 976171e27e.
>
> It is not yet included in 2.26.
>
> The patch is basically the same as I proposed.
>
> I think we should get the upstream version.
>
> 2017-12-04 13:33 GMT+01:00 Gábor Boskovits <boskovits@gmail.com>:
>
>> I think it should look like this:
>>
>> --- cdefs.h 2017-12-04 13:27:55.640000000 +0100
>> +++ cdefs.new.h 2017-12-04 13:31:53.820000000 +0100
>> @@ -1,4 +1,4 @@
>> -/* Copyright (C) 1992-2017 Free Software Foundation, Inc.
>> +y/* Copyright (C) 1992-2017 Free Software Foundation, Inc.
>>     This file is part of the GNU C Library.
>>
>>     The GNU C Library is free software; you can redistribute it and/or
>> @@ -471,10 +471,10 @@
>>     testing __STDC_VERSION__ for generic selection support.
>>     On the other hand, Clang also defines __GNUC__, so a clang-specific
>>     check is required to enable the use of generic selection.  */
>> -#if __GNUC_PREREQ (4, 9) \
>> +#if !defined __cplusplus && (__GNUC_PREREQ (4, 9)   \
>>      || __glibc_clang_has_extension (c_generic_selections) \
>>      || (!defined __GNUC__ && defined __STDC_VERSION__ \
>> - && __STDC_VERSION__ >= 201112L)
>> + && __STDC_VERSION__ >= 201112L))
>>  # define __HAVE_GENERIC_SELECTION 1
>>  #else
>>  # define __HAVE_GENERIC_SELECTION 0
>>
>>
>> 2017-12-04 13:21 GMT+01:00 Gábor Boskovits <boskovits@gmail.com>:
>>
>>> We also have this in bits/floatn.h, but this seems right.
>>>
>>> #if (defined __x86_64__                                                 \
>>>      ? __GNUC_PREREQ (4, 3)                                             \
>>>      : (defined __GNU__ ? __GNUC_PREREQ (4, 5) : __GNUC_PREREQ (4, 4)))
>>> # define __HAVE_FLOAT128 1
>>> #else
>>> # define __HAVE_FLOAT128 0
>>> #endif
>>>
>>> /* Defined to 1 if __HAVE_FLOAT128 is 1 and the type is ABI-distinct
>>>
>>>
>>>    from the default float, double and long double types in this glibc.
>>> */
>>> #if __HAVE_FLOAT128
>>> # define __HAVE_DISTINCT_FLOAT128 1
>>> #else
>>> # define __HAVE_DISTINCT_FLOAT128 0
>>> #endif
>>>
>>> I think the problem is caused by HAVE_GENERIC_SELECTION defined when we
>>> are in C++.
>>>
>>>
>>> 2017-12-04 13:18 GMT+01:00 Gábor Boskovits <boskovits@gmail.com>:
>>>
>>>> We have this in cdefs.h:
>>>> #if __GNUC_PREREQ (4, 9) \
>>>>     || __glibc_clang_has_extension (c_generic_selections) \
>>>>     || (!defined __GNUC__ && defined __STDC_VERSION__ \
>>>>         && __STDC_VERSION__ >= 201112L)
>>>> # define __HAVE_GENERIC_SELECTION 1
>>>> #else
>>>> # define __HAVE_GENERIC_SELECTION 0
>>>> #endif
>>>>
>>>> This does not seem right.
>>>>
>>>> We should not have this defined when compiling c++.
>>>> WDYT?
>>>>
>>>> 2017-12-04 13:03 GMT+01:00 Gábor Boskovits <boskovits@gmail.com>:
>>>>
>>>>> This minimal file reproduces the problem in icu4c 60.1 in guix
>>>>> environment icu4c on current core-updates.
>>>>>
>>>>> #include <cmath>
>>>>>
>>>>> int main(int argc, char **argv)
>>>>> {
>>>>>   std::signbit(1);
>>>>>   return 0;
>>>>> }
>>>>>
>>>>> It seems, that it is some problem with cmath.h
>>>>>
>>>>> /gnu/store/2wzijwwgpcdb1msmn3wgq9zmrbrkpx2h-gcc-5.5.0/includ
>>>>> e/c++/cmath:44:0
>>>>>
>>>>> The definition is in glibc 2.26 math.h, looks like this:
>>>>>
>>>>> #elif __HAVE_DISTINCT_FLOAT128
>>>>> # if __HAVE_GENERIC_SELECTION
>>>>> #  define __MATH_TG(TG_ARG, FUNC, ARGS)         \
>>>>>      _Generic ((TG_ARG),                        \
>>>>>        float: FUNC ## f ARGS,           \
>>>>>                default: FUNC ARGS,              \
>>>>>                long double: FUNC ## l ARGS,     \
>>>>>                _Float128: FUNC ## f128 ARGS)
>>>>>
>>>>>
>>>>>
>>>>> 2017-12-03 23:25 GMT+01:00 Gábor Boskovits <boskovits@gmail.com>:
>>>>>
>>>>>> It seems, that the fix is already included in the 60.1 release for
>>>>>> the xlocal problem. I think we can ignore that.
>>>>>>
>>>>>> 2017-12-03 23:20 GMT+01:00 Gábor Boskovits <boskovits@gmail.com>:
>>>>>>
>>>>>>> It seems, that they issued that already:
>>>>>>> http://bugs.icu-project.org/trac/changeset/40603
>>>>>>>
>>>>>>> 2017-12-03 23:08 GMT+01:00 Gábor Boskovits <boskovits@gmail.com>:
>>>>>>>
>>>>>>>> Ok, I found this one:
>>>>>>>> https://sourceware.org/glibc/wiki/Release/2.26#Removal_of_.2
>>>>>>>> 7xlocale.h.27
>>>>>>>>
>>>>>>>> It seems, that xlocale.h should not be used as an include, and
>>>>>>>> glibc removed that.
>>>>>>>>
>>>>>>>> So this is ok.
>>>>>>>>
>>>>>>>> The question is if this issue was addressed by icu4c, so we can
>>>>>>>> just go to the next step, or should we do something about this.
>>>>>>>>
>>>>>>>>
>>>>>>>> 2017-12-03 23:04 GMT+01:00 Gábor Boskovits <boskovits@gmail.com>:
>>>>>>>>
>>>>>>>>> I've found that simply reverting the update to icu4c 60 commit
>>>>>>>>> brings up the issue you just mentioned, with missing xlocale.h.
>>>>>>>>> So it seems, that the one you found introduced the xlocale
>>>>>>>>> problem, while 4e080fbb0bb73e4444181599676f4e1ef5fdc2ba
>>>>>>>>> introduces the new error.
>>>>>>>>> I think we should deal with the one you find first, the see what's
>>>>>>>>> with this newer one.
>>>>>>>>>
>>>>>>>>> We also have a long running discussion on a bug introduced by a
>>>>>>>>> later glibc update, ee3ebf1a357bd4eb36a2fa1790a7b549cffb305a
>>>>>>>>> which broke a lot of packages. Might these be somehow related?
>>>>>>>>> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=29537
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> 2017-12-03 22:46 GMT+01:00 Chris Marusich <cmmarusich@gmail.com>:
>>>>>>>>>
>>>>>>>>>> Gábor Boskovits <boskovits@gmail.com> writes:
>>>>>>>>>>
>>>>>>>>>> > Any news on this icu4c thing?
>>>>>>>>>>
>>>>>>>>>> After about 2 days of running git bisect, my computer has
>>>>>>>>>> informed me
>>>>>>>>>> that the first bad commit is 67d527e35e367c9e9e89ec01cda2ce
>>>>>>>>>> 32cabd2d89.
>>>>>>>>>> This is the first commit where icu4c fails to build on
>>>>>>>>>> core-updates.
>>>>>>>>>> The build failure at this commit is as follows:
>>>>>>>>>>
>>>>>>>>>> --8<---------------cut here---------------start------------->8---
>>>>>>>>>>    g++   ...  decimfmt.cpp
>>>>>>>>>>    g++   ...  decimalformatpattern.cpp
>>>>>>>>>>    g++   ...  dcfmtsym.cpp
>>>>>>>>>>    g++   ...  digitlst.cpp
>>>>>>>>>>    g++   ...  fmtable_cnv.cpp
>>>>>>>>>> digitlst.cpp:67:24: fatal error: xlocale.h: No such file or
>>>>>>>>>> directory
>>>>>>>>>> compilation terminated.
>>>>>>>>>> *** Failed compilation command follows:
>>>>>>>>>> ----------------------------------------------------------
>>>>>>>>>> g++ -D_REENTRANT -DU_HAVE_ELF_H=1 -DU_HAVE_ATOMIC=1
>>>>>>>>>> -DU_HAVE_STRTOD_L=1 -I. -I../common -DU_ATTRIBUTE_DEPRECATED=
>>>>>>>>>> -DU_I18N_IMPLEMENTATION -O2 -W -Wall -pedantic -Wpointer-arith
>>>>>>>>>> -Wwrite-strings -Wno-long-long --std=c++0x -c -DPIC -fPIC -o digitlst.o
>>>>>>>>>> digitlst.cpp
>>>>>>>>>> --- ( rebuild with "make VERBOSE=1 all" to show all parameters )
>>>>>>>>>> --------
>>>>>>>>>> make[1]: *** [../config/mh-linux:51: digitlst.o] Error 1
>>>>>>>>>> make[1]: *** Waiting for unfinished jobs....
>>>>>>>>>> make[1]: Leaving directory '/tmp/guix-build-icu4c-58.2.dr
>>>>>>>>>> v-0/icu/source/i18n'
>>>>>>>>>> make: *** [Makefile:143: all-recursive] Error 2
>>>>>>>>>> phase `build' failed after 59.0 seconds
>>>>>>>>>> builder for `/gnu/store/mdd6glhc0dg65y4wd11y0b7sbky9cwv6-icu4c-58.2.drv'
>>>>>>>>>> failed with exit code 1
>>>>>>>>>> @ build-failed /gnu/store/mdd6glhc0dg65y4wd11y0b7sbky9cwv6-icu4c-58.2.drv
>>>>>>>>>> - 1 builder for `/gnu/store/mdd6glhc0dg65y4wd11y0b7sbky9cwv6-icu4c-58.2.drv'
>>>>>>>>>> failed with exit code 1
>>>>>>>>>> guix build: error: build failed: build of
>>>>>>>>>> `/gnu/store/mdd6glhc0dg65y4wd11y0b7sbky9cwv6-icu4c-58.2.drv'
>>>>>>>>>> failed
>>>>>>>>>> --8<---------------cut here---------------end--------------->8---
>>>>>>>>>>
>>>>>>>>>> Note that this is NOT the same error as the one that occurs at
>>>>>>>>>> commit
>>>>>>>>>> d6adba786cf2ab1b26ff083928b64262281ff106 (which is the commit on
>>>>>>>>>> core-updates from which Gábor's branch change-default-icedtea-8
>>>>>>>>>> branch
>>>>>>>>>> begins).  That error is:
>>>>>>>>>>
>>>>>>>>>> --8<---------------cut here---------------start------------->8---
>>>>>>>>>>    g++   ...  number_decimalquantity.cpp
>>>>>>>>>>    g++   ...  number_decimfmtprops.cpp
>>>>>>>>>> number_decimalquantity.cpp: In member function
>>>>>>>>>> ‘icu_60::number::impl::DecimalQuantity&
>>>>>>>>>> icu_60::number::impl::DecimalQuantity::setToDouble(double)’:
>>>>>>>>>> number_decimalquantity.cpp:333:9: error: ‘_Generic’ is not a
>>>>>>>>>> member of ‘std’
>>>>>>>>>>      if (std::signbit(n) != 0) {
>>>>>>>>>>          ^
>>>>>>>>>> In file included from /gnu/store/nz2m4gdvgzcrkqa4xwv
>>>>>>>>>> 360iskh7syj7i-gcc-5.5.0/include/c++/cmath:44:0,
>>>>>>>>>>                  from number_decimalquantity.cpp:9:
>>>>>>>>>> number_decimalquantity.cpp:333:14: error: expected
>>>>>>>>>> primary-expression before ‘float’
>>>>>>>>>>      if (std::signbit(n) != 0) {
>>>>>>>>>>               ^
>>>>>>>>>> number_decimalquantity.cpp:333:14: error: expected
>>>>>>>>>> primary-expression before ‘default’
>>>>>>>>>>      if (std::signbit(n) != 0) {
>>>>>>>>>>               ^
>>>>>>>>>> number_decimalquantity.cpp:333:14: error: expected
>>>>>>>>>> primary-expression before ‘long’
>>>>>>>>>>      if (std::signbit(n) != 0) {
>>>>>>>>>>               ^
>>>>>>>>>> number_decimalquantity.cpp:333:14: error: expected
>>>>>>>>>> primary-expression before ‘:’ token
>>>>>>>>>>      if (std::signbit(n) != 0) {
>>>>>>>>>>               ^
>>>>>>>>>> number_decimalquantity.cpp:337:9: error: ‘__builtin_isnan’ is
>>>>>>>>>> not a member of ‘std’
>>>>>>>>>>      if (std::isnan(n) != 0) {
>>>>>>>>>>          ^
>>>>>>>>>> number_decimalquantity.cpp:337:9: note: suggested alternative:
>>>>>>>>>> <built-in>: note:   ‘__builtin_isnan’
>>>>>>>>>> number_decimalquantity.cpp:339:16: error: ‘__builtin_isfinite’
>>>>>>>>>> is not a member of ‘std’
>>>>>>>>>>      } else if (std::isfinite(n) == 0) {
>>>>>>>>>>                 ^
>>>>>>>>>> number_decimalquantity.cpp:339:16: note: suggested alternative:
>>>>>>>>>> <built-in>: note:   ‘__builtin_isfinite’
>>>>>>>>>> *** Failed compilation command follows:
>>>>>>>>>> ----------------------------------------------------------
>>>>>>>>>> g++ -D_REENTRANT -DU_HAVE_ELF_H=1 -DU_HAVE_ATOMIC=1
>>>>>>>>>> -DU_HAVE_STRTOD_L=1 -DU_HAVE_XLOCALE_H=0 -I. -I../common
>>>>>>>>>> -DU_ATTRIBUTE_DEPRECATED= -DU_I18N_IMPLEMENTATION -O2 -W -Wall -pedantic
>>>>>>>>>> -Wpointer-arith -Wwrite-strings -Wno-long-long -std=c++11 -c -DPIC -fPIC -o
>>>>>>>>>> number_decimalquantity.o number_decimalquantity.cpp
>>>>>>>>>> --- ( rebuild with "make VERBOSE=1 all" to show all parameters )
>>>>>>>>>> --------
>>>>>>>>>> make[1]: *** [../config/mh-linux:51: number_decimalquantity.o]
>>>>>>>>>> Error 1
>>>>>>>>>> make[1]: *** Waiting for unfinished jobs....
>>>>>>>>>> make[1]: Leaving directory '/tmp/guix-build-icu4c-60.1.dr
>>>>>>>>>> v-0/icu/source/i18n'
>>>>>>>>>> make: *** [Makefile:149: all-recursive] Error 2
>>>>>>>>>> phase `build' failed after 122.2 seconds
>>>>>>>>>> builder for `/gnu/store/8s6q5cll4knh7y0wfrbjqs2dai0x4sm2-icu4c-60.1.drv'
>>>>>>>>>> failed with exit code 1
>>>>>>>>>> @ build-failed /gnu/store/8s6q5cll4knh7y0wfrbjqs2dai0x4sm2-icu4c-60.1.drv
>>>>>>>>>> - 1 builder for `/gnu/store/8s6q5cll4knh7y0wfrbjqs2dai0x4sm2-icu4c-60.1.drv'
>>>>>>>>>> failed with exit code 1
>>>>>>>>>> guix build: error: build failed: build of
>>>>>>>>>> `/gnu/store/8s6q5cll4knh7y0wfrbjqs2dai0x4sm2-icu4c-60.1.drv'
>>>>>>>>>> failed
>>>>>>>>>> --8<---------------cut here---------------end--------------->8---
>>>>>>>>>>
>>>>>>>>>> The fact that these errors are different suggests that more than
>>>>>>>>>> one
>>>>>>>>>> problem may have been introduced...
>>>>>>>>>>
>>>>>>>>>> I haven't tried any more recent commits on core-updates.  I am
>>>>>>>>>> not sure
>>>>>>>>>> what the best way is to debug this, so I would appreciate any
>>>>>>>>>> advice
>>>>>>>>>> anyone has.
>>>>>>>>>>
>>>>>>>>>> I hope that information helps.  Hopefully, together, we can
>>>>>>>>>> untangle
>>>>>>>>>> this!
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> Chris
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>