Compiler fails unpredictably

[manuels]

I have two rust source files and one c source code file (see this gist).

I compile the code like this:

$ gcc -c function_arg.c -o /tmp/libcxx.a
# clang -c function_arg.c -o /tmp/libcxx.a
# using clang instead of gcc doesn't resolve the issue
$ rustc -o /tmp/libfoo.rlib function_arg.rs
$ rustc -L /tmp/ function_arg_run.rs -o /tmp/main

Most of the times I get this error:

$ rustc -L /tmp/ ././tests/function_arg_run.rs -o /tmp/main
tests/function_arg_run.rs:7:26: 7:36 error: unresolved name `foo::apply`.
tests/function_arg_run.rs:7     unsafe { println!("{}", foo::apply(double, 2)) }
                                                        ^~~~~~~~~~
note: in expansion of format_args!
<std macros>:2:23: 2:77 note: expansion site
<std macros>:1:1: 3:2 note: in expansion of println!
tests/function_arg_run.rs:7:11: 7:50 note: expansion site

But sometimes the code compiles just fine.

The reason seems to lie in the rustc -o /tmp/libfoo.rlib function_arg.rs command.
When I run into the "unresolved name" error, the /tmp/libfoo.rlib has a size of 11012 bytes and does not contain the string "apply".
In the case where everything just compiles fine, /tmp/libfoo.rlib is 4828 bytes and contains "apply" three times:

$ grep apply /tmp/libfoo.rlib --text --only-matching | wc -l
3

I do not change a single line in the source code but the compiler sometimes results in different output files, which is really strange.

I use these versions:

$ rustc -v
rustc 0.13.0-nightly (63c4f22f2 2014-11-05 22:31:44 +0000)
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.7.2-5' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs --enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.7 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable-objc-gc --with-arch-32=i586 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.7.2 (Debian 4.7.2-5) 
$ clang -v
Debian clang version 3.5.0-1~exp1 (trunk) (based on LLVM 3.5.0)
Target: x86_64-pc-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/bin/../lib/gcc/i486-linux-gnu/4.7
Found candidate GCC installation: /usr/bin/../lib/gcc/i486-linux-gnu/4.7.2
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.6.3
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.7.2
Found candidate GCC installation: /usr/lib/gcc/i486-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/i486-linux-gnu/4.7.2
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.2
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.7
Candidate multilib: .;@m64
Selected multilib: .;@m64

[steveklabnik]

I'm going to tag this 'linkage', but I'm not 100% sure that's appropriate. No idea what's going on here, though.

[steveklabnik]

@manuels This bug is extremely old, and nobody has reported anything similar since you've opened it. With some minor updates, your sample compiles fine for me every time, but so much has changed since you filed this bug that I think I'm going to give it a close.

If you're still seeing this, please let me know and we can try to get something that reproduces. Thanks!

[manuels]

Agreed, thanks!