guix: migrate to native GCC 10 toolchain for Linux builds #24701
Description
Currently, our Linux Guix builds differ from macOS and Windows, in that they use a native GCC 7 toolchain (i.e to build glibc) and then GCC 10 to build depends and Bitcoin Core. Migrating the Linux builds to a native GCC 10 toolchain will unify us on a single native compiler.
The main issue with performing this migration is building older glibcs (2.24, 2.27) with GCC 10. When I last tried, it was apparent that either warnings produced by the newer GCC would need to be suppressed (as glibc is built -Werror), or patches to glibc would need to be backported to address any issues. For example:
x86_64-linux-gnu-gcc ../sysdeps/unix/sysv/linux/x86_64/sysdep.S -c -I../include -I/tmp/guix-build-glibc-cross-x86_64-linux-gnu-2.24.drv-0/build/csu -I/tmp/guix-build-glibc-cross-x86_64-linux-gnu-2.24.drv-0/build -I../sysdeps/unix/sysv/linux/x86_64/64 -I../sysdeps/unix/sysv/linux/x86_64 -I../sysdeps/unix/sysv/linux/x86 -I../sysdeps/unix/sysv/linux/wordsize-64 -I../sysdeps/x86_64/nptl -I../sysdeps/unix/sysv/linux/include -I../sysdeps/unix/sysv/linux -I../sysdeps/nptl -I../sysdeps/pthread -I../sysdeps/gnu -I../sysdeps/unix/inet -I../sysdeps/unix/sysv -I../sysdeps/unix/x86_64 -I../sysdeps/unix -I../sysdeps/posix -I../sysdeps/x86_64/64 -I../sysdeps/x86_64/fpu/multiarch -I../sysdeps/x86_64/fpu -I../sysdeps/x86/fpu/include -I../sysdeps/x86/fpu -I../sysdeps/x86_64/multiarch -I../sysdeps/x86_64 -I../sysdeps/x86 -I../sysdeps/ieee754/ldbl-96 -I../sysdeps/ieee754/dbl-64/wordsize-64 -I../sysdeps/ieee754/dbl-64 -I../sysdeps/ieee754/flt-32 -I../sysdeps/wordsize-64 -I../sysdeps/ieee754 -I../sysdeps/generic -I.. -I../libio -I. -nostdinc -isystem /gnu/store/r2h1g2vg7j36rqwyraf5wghm10ykq055-gcc-cross-sans-libc-x86_64-linux-gnu-10.3.0-lib/lib/gcc/x86_64-linux-gnu/10.3.0/include -isystem /gnu/store/r2h1g2vg7j36rqwyraf5wghm10ykq055-gcc-cross-sans-libc-x86_64-linux-gnu-10.3.0-lib/lib/gcc/x86_64-linux-gnu/10.3.0/include-fixed -isystem /gnu/store/5fhhr33nilcyi1k3s1xwcmibdhc1l39c-linux-libre-headers-cross-x86_64-linux-gnu-4.9.306/include -D_LIBC_REENTRANT -include /tmp/guix-build-glibc-cross-x86_64-linux-gnu-2.24.drv-0/build/libc-modules.h -DMODULE_NAME=libc -include ../include/libc-symbols.h -DPIC -DSHARED -DASSEMBLER -I/tmp/guix-build-glibc-cross-x86_64-linux-gnu-2.24.drv-0/build/csu/. -g -Werror=undef -Wa,--noexecstack -o /tmp/guix-build-glibc-cross-x86_64-linux-gnu-2.24.drv-0/build/csu/sysdep.os -MD -MP -MF /tmp/guix-build-glibc-cross-x86_64-linux-gnu-2.24.drv-0/build/csu/sysdep.os.dt -MT /tmp/guix-build-glibc-cross-x86_64-linux-gnu-2.24.drv-0/build/csu/sysdep.os
libc-tls.c: In function ‘__libc_setup_tls’:
libc-tls.c:208:30: error: array subscript 1 is outside the bounds of an interior zero-length array ‘struct dtv_slotinfo[0]’ [-Werror=zero-length-bounds]
208 | static_slotinfo.si.slotinfo[1].map = main_map;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from ../sysdeps/x86_64/ldsodefs.h:54,
from ../sysdeps/gnu/ldsodefs.h:46,
from ../sysdeps/unix/sysv/linux/ldsodefs.h:25,
from libc-tls.c:20:
../sysdeps/generic/ldsodefs.h:398:7: note: while referencing ‘slotinfo’
398 | } slotinfo[0];
| ^~~~~~~~
cc1: all warnings being treated as errorsThis branch could be used as a starting point: https://github.com/fanquake/bitcoin/tree/native_gcc_10_linux (3974ac5). Builds for x86_64-w64-mingw32 x86_64-apple-darwin x86_64-apple-darwin will all work as expected. A Linux build, i.e HOSTS="x86_64-linux-gnu" ./contrib/guix/guix-build will not, and will fail with the error displayed above.
Useful skills:
- Guix
- Build system
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