Doc test link failure with native dependencies

[dcuddeback]

This is reopening #1401. Github doesn't give me the option of reopening the same issue, so I'm creating a new one. I reproduced the issue with the latest Cargo nightly. Here's the output of my test command:

$ cargo clean && cargo test --verbose
   Compiling bug v0.0.1 (file:///Users/david/src/rust-link-bug)
     Running `rustc build.rs --crate-name build_script_build --crate-type bin -C prefer-dynamic -g --out-dir /Users/david/src/rust-link-bug/target/debug/build/bug-7d595e9c49b14df7 --emit=dep-info,link -L dependency=/Users/david/src/rust-link-bug/target/debug -L dependency=/Users/david/src/rust-link-bug/target/debug/deps`
     Running `/Users/david/src/rust-link-bug/target/debug/build/bug-7d595e9c49b14df7/build-script-build`
     Running `rustc src/lib.rs --crate-name bug --crate-type lib -g -C metadata=7d595e9c49b14df7 -C extra-filename=-7d595e9c49b14df7 --out-dir /Users/david/src/rust-link-bug/target/debug --emit=dep-info,link -L dependency=/Users/david/src/rust-link-bug/target/debug -L dependency=/Users/david/src/rust-link-bug/target/debug/deps -L native=/usr/local/Cellar/libusb/1.0.19/lib -l usb-1.0`
     Running `rustc src/lib.rs --crate-name bug --crate-type lib -g --test -C metadata=df6636dbde15889d -C extra-filename=-df6636dbde15889d --out-dir /Users/david/src/rust-link-bug/target/debug --emit=dep-info,link -L dependency=/Users/david/src/rust-link-bug/target/debug -L dependency=/Users/david/src/rust-link-bug/target/debug/deps -L native=/usr/local/Cellar/libusb/1.0.19/lib -l usb-1.0`
     Running `/Users/david/src/rust-link-bug/target/debug/bug-df6636dbde15889d`

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured

   Doc-tests bug
     Running `rustdoc --test /Users/david/src/rust-link-bug/src/lib.rs --crate-name bug -L /Users/david/src/rust-link-bug/target/debug -L /Users/david/src/rust-link-bug/target/debug/deps --extern bug=/Users/david/src/rust-link-bug/target/debug/libbug-7d595e9c49b14df7.rlib`

running 1 test
test hello_0 ... FAILED

failures:

---- hello_0 stdout ----
    error: linking with `cc` failed: exit code: 1
note: "cc" "-m64" "-L" "/usr/local/lib/rustlib/x86_64-apple-darwin/lib" "-o" "/var/folders/7f/z9y9c0gj52gb38jlrsr2pzkc0000gn/T/rustdoctest.e2lupTv465I8/rust_out" "/var/folders/7f/z9y9c0gj52gb38jlrsr2pzkc0000gn/T/rustdoctest.e2lupTv465I8/rust_out.o" "-Wl,-force_load,/usr/local/lib/rustlib/x86_64-apple-darwin/lib/libmorestack.a" "-Wl,-dead_strip" "-nodefaultlibs" "/Users/david/src/rust-link-bug/target/debug/libbug-7d595e9c49b14df7.rlib" "-L" "/usr/local/lib/rustlib/x86_64-apple-darwin/lib" "-lstd-4e7c5e5c" "-L" "/Users/david/src/rust-link-bug/target/debug" "-L" "/Users/david/src/rust-link-bug/target/debug/deps" "-L" "/usr/local/lib/rustlib/x86_64-apple-darwin/lib" "-L" "/Users/david/src/rust-link-bug/.rust/lib/x86_64-apple-darwin" "-L" "/Users/david/src/rust-link-bug/lib/x86_64-apple-darwin" "-lusb-1.0" "-lSystem" "-lpthread" "-lc" "-lm" "-lcompiler-rt"
note: ld: warning: directory not found for option '-L/Users/david/src/rust-link-bug/.rust/lib/x86_64-apple-darwin'
ld: warning: directory not found for option '-L/Users/david/src/rust-link-bug/lib/x86_64-apple-darwin'
ld: library not found for -lusb-1.0
clang: error: linker command failed with exit code 1 (use -v to see invocation)

error: aborting due to previous error
thread 'hello_0' panicked at 'Box<Any>', /Users/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-mac/build/src/libsyntax/diagnostic.rs:152



failures:
    hello_0

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured

thread '<unnamed>' panicked at 'Some tests failed', /Users/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-mac/build/src/libtest/lib.rs:261
thread '<main>' panicked at 'child thread None panicked', /Users/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-mac/build/src/libstd/thread/mod.rs:775

I notice that the two rustc commands both receive the link flags (-L native=/usr/local/Cellar/libusb/1.0.19/lib -l usb-1.0), but the rustdoc command does not. Running the rustdoc command manually with the -L flag works:

$ rustdoc --test /Users/david/src/rust-link-bug/src/lib.rs --crate-name bug -L /Users/david/src/rust-link-bug/target/debug -L /Users/david/src/rust-link-bug/target/debug/deps --extern bug=/Users/david/src/rust-link-bug/target/debug/libbug-7d595e9c49b14df7.rlib -L native=/usr/local/Cellar/libusb/1.0.19/lib

running 1 test
test hello_0 ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured

I also tried with Cargo built from the latest master branch, just to make sure I had the fixes from #1441.

[alexcrichton]

Fixed in #1530 (purportedly). Feel free to comment if it still reproduces though!