librustc *still* cannot be used as a library? (trouble resolving libstd)

[killerswan]

Moving on from #11026 (where I was missing args[0]), now I'm seeing this at runtime:

$ ./bin/testloop src/demo.rs 
Error in `stat` on `./.tests_in_loop.exe`: std::io::IoError{kind: OtherIoError, desc: "no such file or directory", detail: None}
<<<< building tests >>>>
src/demo.rs:1:0: 1:0 error: can't find crate for `std`
src/demo.rs:1 #[feature(non_ascii_idents)];
              ^
task 'rustc' failed at 'explicit failure', /Users/kevin/code/rust/src/libsyntax/diagnostic.rs:76
task '<main>' failed at 'explicit failure', /Users/kevin/code/rust/src/librustc/lib.rs:398

Where testloop is my program calling rustc::main_args (and trying to build demo.rs)...

cc @alexcrichton

[alexcrichton]

Closing this as working as intended.

Sadly rustc isn't designed to be the easiest library to use right now, but rustc for better or for worse has a lot of inference based on self_exe_path() of where to find the target libraries to link against (it's tough to find another way). The best fix for this would be to specify the sysroot manually or to also specify an addl_lib_search_path (or something called along those lines). We arguably need better support for finding libraries when using rustc as a library, but for now I don't think that there's much in the way of improving this.

If there are ideas though about how to make guessing where the target libraries are more robust, then that would be fantastic to commit to rustc! For now though, with a lack of ideas, I'm going to close this issue.

[alexcrichton]

I have opened #11068 as a specific way to go about fixing this issue.