ICE when using lto and prefer-dynamic

[Armavica]

System info:

$ uname -a
Linux Serenno 3.2.0-4-amd64 #1 SMP Debian 3.2.51-1 x86_64 GNU/Linux

$ rustc --version
rustc 0.9-pre (a1e68de 2013-12-24 20:11:33 -0800)
host: x86_64-unknown-linux-gnu

Running rustc on hello world with -Z lto -Z prefer-dynamic produces the following crash:

$ cat > hello.rs
fn main() { println("Hello world!"); }

$ rustc hello.rs -Z lto -Z prefer-dynamic
task 'rustc' failed at 'assertion failed: !sess.lto()', /home/virgile/.local/src/rust/src/librustc/back/link.rs:1189
error: internal compiler error: unexpected failure
This message reflects a bug in the Rust compiler. 
We would appreciate a bug report: https://github.com/mozilla/rust/wiki/HOWTO-submit-a-Rust-bug-report
note: the compiler hit an unexpected failure path. this is a bug
note: try running with RUST_LOG=rustc=1 to get further details and report the results to github.com/mozilla/rust/issues
task '<main>' failed at 'explicit failure', /home/virgile/.local/src/rust/src/librustc/lib.rs:442

The debug output ends with:

$ RUST_LOG=rustc rustc hello.rs -Z lto -Z prefer-dynamic
[...]
reading std
linking std
reading rustuv
linking rustuv
running the pass manager
lto done
task 'rustc' failed at 'assertion failed: !sess.lto()', /home/virgile/.local/src/rust/src/librustc/back/link.rs:1189
error: internal compiler error: unexpected failure
This message reflects a bug in the Rust compiler. 
We would appreciate a bug report: https://github.com/mozilla/rust/wiki/HOWTO-submit-a-Rust-bug-report
note: the compiler hit an unexpected failure path. this is a bug
note: try running with RUST_LOG=rustc=1 to get further details and report the results to github.com/mozilla/rust/issues
task '<main>' failed at 'explicit failure', /home/virgile/.local/src/rust/src/librustc/lib.rs:442

[alexcrichton]

That would be my fault. I was even aware of this at the time of writing, I just wasn't proactive enough to gracefully handle this.

This will always be an error because LTO can only be done for static libs and executables, but the error message should certainly be a bit more amenable.