Make backtraces work on Redox, copying Unix implementation

[ids1024]

The backtrace/ directory here is the same as the Unix one, except for adding an implementation of get_executable_filename.

[rust-highfive]

r? @brson

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[NilSet]

Redox is never macos, so no need for dladdr.rs

[ids1024]

True; I thought it might be best not to modify those files too much (I just changed get_executable_filename in mod.rs) so they can be easily synced with the Unix version, but otherwise several things could be removed.

The duplicated code is somewhat annoying; I don't think it's avoidable though.

[ids1024]

I guess (multiple) entire files that are useless is probably a waste, so I've pushed a commit addressing this.

[arielb1]

ping @brson - be our rubber stamp

[jackpot51]

@brson @arielb1 @shepmaster Any updates on this?

[alexcrichton]

Thanks @ids1024! Out of curiosity, where'd the changes to config.sub come from? We ideally like to stick pretty close to upstream, but if it's pretty easy to re-apply the changes to upstream that shouldn't be too bad.

[ids1024]

I could change the config.sub modification to just the single line required for Redox, but I though it was best to just update it from GNU: http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob;f=config.sub

Future releases of libbacktrace will probably have that fix.

[alexcrichton]

Ok I don't really know what config.sub is anyway but the commit message is at least clear enough to me of how to reproduce it!

In that case let's...

@bors: r+

[bors]

📌 Commit 9d67d5a has been approved by alexcrichton

[ids1024]

config.sub is used by autotools to get the canonical name of the system from the target triplet (trivial for most systems, but a few have several variations of their triplets that it needs to handle). It needs to be updated when new systems are added.

config.guess is similar; it guesses a target triplet based on uname output. That is only relevant for native compilation though.

TLDR: It's one of the weird and ugly things in autotools that seem awful, but does help with portability to various strange systems.

This update seems to add fuchsia as well, so if they decide to implement Rust backtraces they won't run into that (small) issue.

[bors]

⌛ Testing commit 9d67d5a with merge f25c228...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: alexcrichton
Pushing f25c228 to master...