Bug#996828: llvm-toolchain-12: FTBFS on armel|armhf since 1:12.0.1-10: fatal error: 'gnu/stubs-(hard|soft).h' file not found

[Simon McVittie]

Source: llvm-toolchain-12
Version: 1:12.0.1-8
Severity: serious
Tags: ftbfs
Justification: fails to build from source (but built successfully in the past)

https://buildd.debian.org/status/fetch.php?pkg=llvm-toolchain-12&arch=armel&ver=1%3A12.0.1-10&stamp=1634598677&raw=0
> /<<PKGBUILDDIR>>/build-llvm/./bin/clang --target=arm-linux-gnueabi -DVISIBILITY_HIDDEN  -g -O2 -fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -O3 -DNDEBUG  -march=armv7-a -mfloat-abi=hard -DCOMPILER_RT_HAS_FLOAT16 -std=c11 -fPIC -fno-builtin -fvisibility=hidden -fomit-frame-pointer -fomit-frame-pointer -DCOMPILER_RT_ARMHF_TARGET -MD -MT CMakeFiles/clang_rt.builtins-armhf.dir/ctzsi2.c.o -MF CMakeFiles/clang_rt.builtins-armhf.dir/ctzsi2.c.o.d -o CMakeFiles/clang_rt.builtins-armhf.dir/ctzsi2.c.o -c /<<PKGBUILDDIR>>/compiler-rt/lib/builtins/ctzsi2.c
> In file included from /<<PKGBUILDDIR>>/compiler-rt/lib/builtins/ctzsi2.c:13:
> In file included from /<<PKGBUILDDIR>>/compiler-rt/lib/builtins/int_lib.h:84:
> In file included from /<<PKGBUILDDIR>>/build-llvm/lib/clang/12.0.1/include/limits.h:21:
> In file included from /usr/include/limits.h:26:
> In file included from /usr/include/arm-linux-gnueabi/bits/libc-header-start.h:33:
> In file included from /usr/include/features.h:485:
> /usr/include/arm-linux-gnueabi/gnu/stubs.h:10:11: fatal error: 'gnu/stubs-hard.h' file not found
> # include <gnu/stubs-hard.h>
>           ^~~~~~~~~~~~~~~~~~

https://buildd.debian.org/status/fetch.php?pkg=llvm-toolchain-12&arch=armhf&ver=1%3A12.0.1-10&stamp=1634254382&raw=0
> /<<PKGBUILDDIR>>/build-llvm/./bin/clang --target=armv7l-unknown-linux-gnueabihf -DVISIBILITY_HIDDEN  -g -O2 -fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -O3 -DNDEBUG  -march=armv6m -mfloat-abi=soft -DCOMPILER_RT_HAS_FLOAT16 -std=c11 -fPIC -fno-builtin -fvisibility=hidden -fomit-frame-pointer -fomit-frame-pointer -DCOMPILER_RT_ARMHF_TARGET -MD -MT CMakeFiles/clang_rt.builtins-armv6m.dir/absvdi2.c.o -MF CMakeFiles/clang_rt.builtins-armv6m.dir/absvdi2.c.o.d -o CMakeFiles/clang_rt.builtins-armv6m.dir/absvdi2.c.o -c /<<PKGBUILDDIR>>/compiler-rt/lib/builtins/absvdi2.c
> In file included from /<<PKGBUILDDIR>>/compiler-rt/lib/builtins/absvdi2.c:13:
> In file included from /<<PKGBUILDDIR>>/compiler-rt/lib/builtins/int_lib.h:84:
> In file included from /<<PKGBUILDDIR>>/build-llvm/lib/clang/12.0.1/include/limits.h:21:
> In file included from /usr/include/limits.h:26:
> In file included from /usr/include/arm-linux-gnueabihf/bits/libc-header-start.h:33:
> In file included from /usr/include/features.h:485:
> /usr/include/arm-linux-gnueabihf/gnu/stubs.h:7:11: fatal error: 'gnu/stubs-soft.h' file not found
> # include <gnu/stubs-soft.h>
>           ^~~~~~~~~~~~~~~~~~

These look like the inverse of each other: on armel, the necessary headers
for an armhf biarch runtime library aren't found, and on armhf, the
necessary headers for an armel biarch runtime library aren't found.

    smcv