Failed to build rpm-ostree on ppc64le: multiple definition of `__fixdfdi'

[cuviper]

ref: https://bugzilla.redhat.com/show_bug.cgi?id=1713090

Trying to build rpm-ostree on Fedora ppc64le now gives:

libtool: link: gcc -shared  -fPIC -DPIC  src/lib/.libs/librpmostree_1_la-rpmostree.o src/lib/.libs/librpmostree_1_la-rpmostree-db.o src/lib/.libs/librpmostree_1_la-rpmostree-package.o  -Wl,--whole-archive ./.libs/librpmostreepriv.a -Wl,--no-whole-archive  -L/builddir/build/BUILD/rpm-ostree-2019.4/libdnf-build/libdnf -ldnf -ljson-glib-1.0 -lostree-1 -lsystemd -lpolkit-gobject-1 -lrpm -lrpmio -lrepo -lsolv -larchive -lgio-2.0 -lgobject-2.0 -lglib-2.0 -lcap /builddir/build/BUILD/rpm-ostree-2019.4/target/release/librpmostree_rust.a -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -pthread -O2 -g -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mcpu=power8 -mtune=power8 -Wl,-rpath=/usr/lib64/rpm-ostree -Wl,-z -Wl,relro -Wl,--as-needed -Wl,-z -Wl,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -Wl,--push-state -Wl,--no-as-needed -Wl,-ldl -Wl,-lm -Wl,--pop-state   -pthread -Wl,-soname -Wl,librpmostree-1.so.1 -o .libs/librpmostree-1.so.1.0.0
BUILDSTDERR: /usr/bin/ld: /usr/lib/gcc/ppc64le-redhat-linux/9/libgcc.a(ppc64-fp.o): in function `__fixdfdi':
BUILDSTDERR: (.text+0x510): multiple definition of `__fixdfdi'; /builddir/build/BUILD/rpm-ostree-2019.4/target/release/librpmostree_rust.a(compiler_builtins-cae9ea46cd4dabd1.compiler_builtins.qr7h34vq-cgu.0.rcgu.o):(.text.__fixdfdi+0x0): first defined here
BUILDSTDERR: /usr/bin/ld: /usr/lib/gcc/ppc64le-redhat-linux/9/libgcc.a(ppc64-fp.o): in function `__fixsfdi':
BUILDSTDERR: (.text+0x5c0): multiple definition of `__fixsfdi'; /builddir/build/BUILD/rpm-ostree-2019.4/target/release/librpmostree_rust.a(compiler_builtins-cae9ea46cd4dabd1.compiler_builtins.qr7h34vq-cgu.0.rcgu.o):(.text.__fixsfdi+0x0): first defined here
BUILDSTDERR: /usr/bin/ld: /usr/lib/gcc/ppc64le-redhat-linux/9/libgcc.a(ppc64-fp.o): in function `__fixunsdfsi':
BUILDSTDERR: (.text+0x680): multiple definition of `__fixunsdfsi'; /builddir/build/BUILD/rpm-ostree-2019.4/target/release/librpmostree_rust.a(compiler_builtins-cae9ea46cd4dabd1.compiler_builtins.qr7h34vq-cgu.0.rcgu.o):(.text.__fixunsdfsi+0x0): first defined here
BUILDSTDERR: /usr/bin/ld: /usr/lib/gcc/ppc64le-redhat-linux/9/libgcc.a(ppc64-fp.o): in function `__fixunssfsi':
BUILDSTDERR: (.text+0x6e0): multiple definition of `__fixunssfsi'; /builddir/build/BUILD/rpm-ostree-2019.4/target/release/librpmostree_rust.a(compiler_builtins-cae9ea46cd4dabd1.compiler_builtins.qr7h34vq-cgu.0.rcgu.o):(.text.__fixunssfsi+0x0): first defined here
BUILDSTDERR: /usr/bin/ld: /usr/lib/gcc/ppc64le-redhat-linux/9/libgcc.a(ppc64-fp.o): in function `__floatdidf':
BUILDSTDERR: (.text+0x800): multiple definition of `__floatdidf'; /builddir/build/BUILD/rpm-ostree-2019.4/target/release/librpmostree_rust.a(compiler_builtins-cae9ea46cd4dabd1.compiler_builtins.qr7h34vq-cgu.0.rcgu.o):(.text.__floatdidf+0x0): first defined here
BUILDSTDERR: /usr/bin/ld: /usr/lib/gcc/ppc64le-redhat-linux/9/libgcc.a(ppc64-fp.o): in function `__floatundidf':
BUILDSTDERR: (.text+0x840): multiple definition of `__floatundidf'; /builddir/build/BUILD/rpm-ostree-2019.4/target/release/librpmostree_rust.a(compiler_builtins-cae9ea46cd4dabd1.compiler_builtins.qr7h34vq-cgu.0.rcgu.o):(.text.__floatundidf+0x0): first defined here
BUILDSTDERR: /usr/bin/ld: /usr/lib/gcc/ppc64le-redhat-linux/9/libgcc.a(ppc64-fp.o): in function `__floatdisf':
BUILDSTDERR: (.text+0x880): multiple definition of `__floatdisf'; /builddir/build/BUILD/rpm-ostree-2019.4/target/release/librpmostree_rust.a(compiler_builtins-cae9ea46cd4dabd1.compiler_builtins.qr7h34vq-cgu.0.rcgu.o):(.text.__floatdisf+0x0): first defined here
BUILDSTDERR: /usr/bin/ld: /usr/lib/gcc/ppc64le-redhat-linux/9/libgcc.a(ppc64-fp.o): in function `__floatundisf':
BUILDSTDERR: (.text+0x900): multiple definition of `__floatundisf'; /builddir/build/BUILD/rpm-ostree-2019.4/target/release/librpmostree_rust.a(compiler_builtins-cae9ea46cd4dabd1.compiler_builtins.qr7h34vq-cgu.0.rcgu.o):(.text.__floatundisf+0x0): first defined here
BUILDSTDERR: collect2: error: ld returned 1 exit status

We reproduced this with Fedora 29 (with LLVM 7) as well as Fedora 30 and 31 (LLVM 8). It fails consistently with 1.34.2, but strangely it succeeds with 1.34.1. There were no packaging changes between those, apart from the version update for the CVE fix.

I also reproduced this with official Rust builds, from 1.36.0-nightly (37ff5d388 2019-05-22) all the way back to 1.32.0. However, it builds fine with 1.31.1!
(For releases before 1.35, lacking #58986, I used Fedora's cargo to avoid that SIGILL.)

I find it especially strange that the regression point is inconsistent...

[cuviper]

It fails consistently with 1.34.2, but strangely it succeeds with 1.34.1. There were no packaging changes between those, apart from the version update for the CVE fix.

I missed something -- I actually added --set rust.codegen-units-std=1 in that build too.

In the official builds, this option was added and enabled in commit b8f977a of #55264, which made it to release in 1.32.0. So this appears to be the important factor in the regression.

cc @michaelwoerister @Mark-Simulacrum from that PR.