Link error in rustc-main: undefined reference to `__floatundisf'

[nnethercote]

I just updated to 763d91a and when building the compiler I get a link error on rustc-main:

Building stage0 compiler artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
   Compiling version_check v0.1.4                                               
   Compiling cfg-if v0.1.5
   Compiling nodrop v0.1.12
   Compiling memoffset v0.2.1
   Compiling scopeguard v0.3.3
   Compiling void v1.0.2
   Compiling libc v0.2.43
   Compiling rustc-rayon-core v0.1.1
   Compiling stable_deref_trait v1.1.0
   Compiling byteorder v1.2.3
   Compiling bitflags v1.0.4
   Compiling either v1.5.0
   Compiling unicode-width v0.1.5
   Compiling scoped-tls v0.1.2
   Compiling cc v1.0.22
   Compiling rustc_target v0.0.0 (file:///home/njn/moz/rust1/src/librustc_target)
   Compiling syntax v0.0.0 (file:///home/njn/moz/rust1/src/libsyntax)
   Compiling termcolor v0.3.6
   Compiling rand_core v0.2.1
   Compiling lazy_static v0.2.11
   Compiling rustc-demangle v0.1.9
   Compiling remove_dir_all v0.5.1
   Compiling rustc v0.0.0 (file:///home/njn/moz/rust1/src/librustc)
   Compiling datafrog v0.1.0
   Compiling fmt_macros v0.0.0 (file:///home/njn/moz/rust1/src/libfmt_macros)
   Compiling rustc_fs_util v0.0.0 (file:///home/njn/moz/rust1/src/librustc_fs_util)
   Compiling graphviz v0.0.0 (file:///home/njn/moz/rust1/src/libgraphviz)
   Compiling rustc_metadata v0.0.0 (file:///home/njn/moz/rust1/src/librustc_metadata)
   Compiling rustc_incremental v0.0.0 (file:///home/njn/moz/rust1/src/librustc_incremental)
   Compiling rustc-serialize v0.3.24
   Compiling rustc_platform_intrinsics v0.0.0 (file:///home/njn/moz/rust1/src/librustc_platform_intrinsics)
   Compiling quick-error v1.2.2
   Compiling termcolor v1.0.2
   Compiling rustc_driver v0.0.0 (file:///home/njn/moz/rust1/src/librustc_driver)
   Compiling arrayvec v0.4.7
   Compiling unreachable v1.0.0
   Compiling crossbeam-utils v0.2.2
   Compiling log v0.4.4
   Compiling chalk-macros v0.1.0
   Compiling owning_ref v0.3.3
   Compiling humantime v1.1.1
   Compiling smallvec v0.6.5
   Compiling lazy_static v1.1.0
   Compiling rustc-hash v1.0.1
   Compiling rustc_cratesio_shim v0.0.0 (file:///home/njn/moz/rust1/src/librustc_cratesio_shim)
   Compiling ena v0.9.3
   Compiling serialize v0.0.0 (file:///home/njn/moz/rust1/src/libserialize)
   Compiling polonius-engine v0.5.0
   Compiling rustc_apfloat v0.0.0 (file:///home/njn/moz/rust1/src/librustc_apfloat)
   Compiling chalk-engine v0.7.0
   Compiling num_cpus v1.8.0
   Compiling rand v0.4.3
   Compiling atty v0.2.11
   Compiling rand v0.5.4
   Compiling jobserver v0.1.11
   Compiling crossbeam-epoch v0.3.1
   Compiling log_settings v0.1.2
   Compiling env_logger v0.5.12
   Compiling crossbeam-deque v0.2.0
   Compiling parking_lot_core v0.2.14
   Compiling parking_lot v0.5.5
   Compiling backtrace-sys v0.1.24
   Compiling miniz-sys v0.1.10
   Compiling tempfile v3.0.3
   Compiling rustc-rayon v0.1.1
   Compiling flate2 v1.0.2
   Compiling backtrace v0.3.9
   Compiling rls-span v0.4.0
   Compiling rustc_data_structures v0.0.0 (file:///home/njn/moz/rust1/src/librustc_data_structures)
   Compiling rls-data v0.18.0
   Compiling arena v0.0.0 (file:///home/njn/moz/rust1/src/libarena)
   Compiling syntax_pos v0.0.0 (file:///home/njn/moz/rust1/src/libsyntax_pos)
   Compiling rustc_errors v0.0.0 (file:///home/njn/moz/rust1/src/librustc_errors)
   Compiling proc_macro v0.0.0 (file:///home/njn/moz/rust1/src/libproc_macro)
   Compiling syntax_ext v0.0.0 (file:///home/njn/moz/rust1/src/libsyntax_ext)
   Compiling rustc_metadata_utils v0.0.0 (file:///home/njn/moz/rust1/src/librustc_metadata_utils)
   Compiling rustc_mir v0.0.0 (file:///home/njn/moz/rust1/src/librustc_mir)
   Compiling rustc_typeck v0.0.0 (file:///home/njn/moz/rust1/src/librustc_typeck)
   Compiling rustc_traits v0.0.0 (file:///home/njn/moz/rust1/src/librustc_traits)
   Compiling rustc_allocator v0.0.0 (file:///home/njn/moz/rust1/src/librustc_allocator)
   Compiling rustc_resolve v0.0.0 (file:///home/njn/moz/rust1/src/librustc_resolve)
   Compiling rustc_plugin v0.0.0 (file:///home/njn/moz/rust1/src/librustc_plugin)
   Compiling rustc_privacy v0.0.0 (file:///home/njn/moz/rust1/src/librustc_privacy)
   Compiling rustc_save_analysis v0.0.0 (file:///home/njn/moz/rust1/src/librustc_save_analysis)
   Compiling rustc_lint v0.0.0 (file:///home/njn/moz/rust1/src/librustc_lint)
   Compiling rustc_borrowck v0.0.0 (file:///home/njn/moz/rust1/src/librustc_borrowck)
   Compiling rustc_codegen_utils v0.0.0 (file:///home/njn/moz/rust1/src/librustc_codegen_utils)
   Compiling rustc_passes v0.0.0 (file:///home/njn/moz/rust1/src/librustc_passes)
   Compiling rustc-main v0.0.0 (file:///home/njn/moz/rust1/src/rustc)
error: linking with `cc` failed: exit code: 1
  |
  = note: "cc" "-Wl,--as-needed" "-Wl,-z,noexecstack" "-m64" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-sysroot/lib/rustlib/x86_64-unknown-linux-gnu/lib" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/rustc_binary-28f89886f0c64dae.rustc_binary0.rcgu.o" "-o" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/rustc_binary-28f89886f0c64dae" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/rustc_binary-28f89886f0c64dae.crate.allocator.rcgu.o" "-Wl,--gc-sections" "-pie" "-Wl,-zrelro" "-Wl,-znow" "-Wl,-O1" "-nodefaultlibs" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/release/deps" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/build/backtrace-sys-ee16f6821aef40e9/out" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/build/miniz-sys-52504d5ed57fefc2/out" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-sysroot/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_driver-490c048ff54b9a93" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_codegen_utils-3740581f350307fa" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_traits-6465f6e98200a700" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_save_analysis-4d060cea5dcf2998" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_resolve-388483db27fc0cd1" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_incremental-d391c0d774c533b4" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_privacy-76a4ac68dda3f42e" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_typeck-ec65b35f7eb40d9c" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_platform_intrinsics-2e835ba951928190" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_plugin-44c7033156dc49bf" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_metadata-526be4055a895339" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_metadata_utils-c906ffe575b45aa6" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lsyntax_ext-b179f38562a2d398" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_lint-6d56074750519d82" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_passes-a0b8e31400606347" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_borrowck-c2b68476772843c1" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_mir-6b1f07dbc06b744f" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_allocator-51a22fde4b0db5bd" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc-171066954813e178" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-sysroot/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-ltest-5ddc8f9584faca79" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-sysroot/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-lterm-76f8ef2b02a12b3e" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_fs_util-3f97c3ca5071d1e2" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lproc_macro-f7c6fbe761b432aa" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lsyntax-155aeebbdb4c7e8b" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_errors-f882aab6100635ab" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lsyntax_pos-ef45b71e578357b1" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_target-2d6cba9c2df54bd6" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lfmt_macros-2ce739823c85fd99" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lgraphviz-45ae4394366d07fd" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-larena-4ee92b74dcb65ca6" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_data_structures-61336079186baa43" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lrustc_cratesio_shim-b41313cb9de684df" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps" "-lserialize-8d84add221c0f710" "-Wl,--start-group" "-L" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-sysroot/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-lstd-bd7ba1c2aaa31ca8" "-Wl,--end-group" "-Wl,-Bstatic" "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-sysroot/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-02d8b7c22d5a49ce.rlib" "-Wl,-Bdynamic" "-lutil" "-lutil" "-ldl" "-lrt" "-lpthread" "-lgcc_s" "-lc" "-lm" "-lrt" "-lpthread" "-lutil" "-lutil" "-Wl,-rpath,$ORIGIN/../lib"
  = note: /home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/librustc_driver-490c048ff54b9a93.so: undefined reference to `__floatundisf'
          collect2: error: ld returned 1 exit status
          

error: aborting due to previous error

error: Could not compile `rustc-main`.

Caused by:
  process didn't exit successfully: `/home/njn/moz/rust1/build/bootstrap/debug/rustc --crate-name rustc_binary rustc/rustc.rs --error-format json --crate-type bin --emit=dep-info,link -C opt-level=2 -C metadata=28f89886f0c64dae -C extra-filename=-28f89886f0c64dae --out-dir /home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps --target x86_64-unknown-linux-gnu -L dependency=/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps -L dependency=/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/release/deps --extern rustc_driver=/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/librustc_driver-490c048ff54b9a93.so --extern rustc_target=/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/librustc_target-2d6cba9c2df54bd6.so -L native=/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/build/backtrace-sys-ee16f6821aef40e9/out -L native=/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/build/miniz-sys-52504d5ed57fefc2/out` (exit code: 1)
command did not execute successfully: "/home/njn/moz/rust1/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "x86_64-unknown-linux-gnu" "-j" "28" "--release" "--features" "" "--manifest-path" "/home/njn/moz/rust1/src/rustc/Cargo.toml" "--message-format" "json"
expected success, got: exit code: 101
thread 'main' panicked at 'cargo must succeed', bootstrap/compile.rs:1155:9
note: Run with `RUST_BACKTRACE=1` for a backtrace.
failed to run: /home/njn/moz/rust1/build/bootstrap/debug/bootstrap build --stage 2 src/rustc
Build completed unsuccessfully in 0:14:33

This is on my Ubuntu 18.04 box, which is pretty ordinary and doesn't have anything special about it.

[nnethercote]

When I compile a fresh clone with this config.toml, it works:

[rust]
codegen-units = 20
debuginfo = true
debuginfo-lines = true

It does an LLVM compile and install while doing this.

When I compile a fresh clone with this config.toml, I get the link error:

[llvm]
optimize = true
release-debuginfo = true
assertions = false
[rust]
optimize = true
codegen-units = 1
debug-assertions = false
debuginfo = true
debuginfo-lines = true
use-jemalloc = false

It doesn't do an LLVM compile and install.

[nnethercote]

To clarify, the problem doesn't occur when I do this:

./x.py build --stage 1 src/libtest

But it does happen when I do this:

./x.py build --stage 2 src/rustc

[alexcrichton]

I think this line may be incorrect. That says that on non-windows x86_64 we should use a C shim but we fail to compile the C shim!

I believe this was a bug introduced in rust-lang/compiler-builtins#252

cc @dingelish

[alexcrichton]

@nnethercote I think I've fixed this on the master branch of compiler-builtins, can you try updating the src/libcompiler_builtins submodule and see if it fixes the issue for you? If so I can send a PR to update it.

[nnethercote]

@alexcrichton: I did the following:

cd src/libcompiler_builtins
git co master
git pull
cd ../..

With this, the submodule is on tip and I have your C shim patch. But then when I build with ./x.py build --stage 2 src/rustc, it starts with this:

Updating only changed submodules
Updating submodule src/libcompiler_builtins
Submodule path 'src/libcompiler_builtins': checked out 'f3a13eb2384c7cbb91b6db5b008377e9710d434c'
Submodules updated in 0.29 seconds

which takes me back to the original libcompiler_builtins revision and the link error (unsurprisingly) still occurs. How can I preserve the libcompiler_builtins revision?

[nnethercote]

rkruppe told me on IRC to set submodules = false in config.toml. With that in place, it compiles again!

[oli-obk]

I've been bitten by this before when I created a new checkout of rustc. This setting completely overwrites any changes, even uncommited ones.

Maybe we can change the default to false?

[alexcrichton]

@oli-obk perhaps, but we should discuss that its own issue rather than here most likely