Repository: rust
Issue: Failed to build rpm-ostree on ppc64le: multiple definition of `__fixdfdi'
Labels: T-libs-api,O-PowerPC,C-bug,A-intrinsics

ref: https://bugzilla.redhat.com/show_bug.cgi?id=1713090

Trying to build [rpm-ostree](https://github.com/projectatomic/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...