Error: unknown codegen option: `embed-bitcode`

help
#1

I am currently trying to compile a crate on a centos7 machine and I get the following error:

error: unknown codegen option: `embed-bitcode`

error: could not compile `env_logger`

(My first report: here, but it has nothing to do with the env_logger crate)

Apparently, the rust compiler gets an argument --embed-bitcode=no which it does not understand. This happens with rustc 1.48.0 and 1.47.0. I am not cross-compiling anything.

Can someone help me with this issue?

1 Like
#2

Is it possible that you have multiple versions of Rust installed? or Cargo newer than rustc? This option requires Rust 1.45 or later.

#3

which -a reports three rust binaries, but they all have the exact same --version output.

#4 
$ rustc --version && cargo --version
rustc 1.48.0 (7eac88abb 2020-11-16)
cargo 1.48.0 (65cbdd2dc 2020-10-14)
#5

What is the output of cat target/.rustc_info.json? This should show the exact rustc version that cargo is using alongside other things.

#6 
$ \cat target/.rustc_info.json | json_pp
{
   "outputs" : {
      "1164083562126845933" : [
         "rustc 1.48.0 (7eac88abb 2020-11-16)\nbinary: rustc\ncommit-hash: 7eac88abb2e57e752f3302f02be5f3ce3d7adfb4\ncommit-date: 2020-11-16\nhost: x86_64-unknown-linux-gnu\nrelease: 1.48.0\nLLVM version: 11.0\n",
         ""
      ],
      "4476964694761187371" : [
         "___\nlib___.rlib\nlib___.so\nlib___.so\nlib___.a\nlib___.so\n/home/beyer/.rustup/toolchains/stable-x86_64-unknown-linux-gnu\ndebug_assertions\nproc_macro\ntarget_arch=\"x86_64\"\ntarget_endian=\"little\"\ntarget_env=\"gnu\"\ntarget_family=\"unix\"\ntarget_feature=\"fxsr\"\ntarget_feature=\"sse\"\ntarget_feature=\"sse2\"\ntarget_os=\"linux\"\ntarget_pointer_width=\"64\"\ntarget_vendor=\"unknown\"\nunix\n", 
         ""
      ]
   },
   "successes" : {},
   "rustc_fingerprint" : 9251463643064323083
}
#7

That doesn't look like a version mix-up. Strange.

#8

Strangely enough, the issue vanished and I was not able to reproduce it.
Either way, thank you!

#9

I'm getting the xact same error while trying to cross compile FIrefox on Ubuntu for Solaris SPARC. The error pops up while executing mach build but I can reproduce it by executing that one command directly from the command line:
michele@michele-VirtualBox:/usr/sparcv9-solaris/solaris/cross/bin$ /home/michele/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc - --crate-name ___ --print=file-names -C opt-level=2 -C debuginfo=2 --cap-lints warn -C -Cembed-bitcode=yes -C codegen-units=1 --target sparcv9-sun-solaris --crate-type bin --crate-type rlib --crate-type dylib --crate-type cdylib --crate-type staticlib --crate-type proc-macro --print=sysroot --print=cfg
error: unknown codegen option: -Cembed-bitcode
michele@michele-VirtualBox:~/mozilla-unified$ rustc --version && cargo --version
rustc 1.49.0 (e1884a8e3 2020-12-29)
cargo 1.49.0 (d00d64df9 2020-12-05)
I note that if I remove the "-C" immediately before "-Cembed-bitcode" the command works. What does this -C do? Any ideas?

#10

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