Implement addr2line

[khuey]

This definitely isn't ready for merging yet, but it might be ready to look at.

Notable todos:

• Should we factor out object loading support for the examples/ somewhere?
• Should parsing DW_AT_stmt_list be handled inside gimli somewhere? (probably)
• Get the directory name instead of just printing the index

[fitzgen]

Should we factor out object loading support for the examples/ somewhere?

That would be great. I don't know if we can add modules to examples/ or not, but I feel like the obj loading doesn't belong in the library proper (especially as it is currently implemented).

Maybe we should factor it out into a new crate and do it Right (unless some other crate abstracting obj files already exists that seems good enough).

Should parsing DW_AT_stmt_list be handled inside gimli somewhere? (probably)

Yes, it is on my TODO list to make a method on UnitHeader that takes the DebugLine and returns the LineNumberProgramHeader (probably as an Option because it might not exist and I'm also unsure whether partial units have them). First, I need to write more unit tests for line number program execution, however. Feel free to make that method yourself, if you want, as you'll probably be able to beat me to the punch.

[fitzgen]

This should be under [dev-dependencies], which are only included for tests and examples.

http://doc.crates.io/specifying-dependencies.html#development-dependencies

[khuey]

Done.

[khuey]

This is ready for another pass, @fitzgen.

[fitzgen]

Nit: rust style is to leave out return and the semicolon when in tail position.

It's not just functions either. Rust's block "statements" will evaluate to their last expression, if you drop the semicolon, eg:

let foo = {
    bar();
    1
};
assert_eq(foo, 1);

Same for ifs, etc.

[khuey]

Yeah, I know this, but it's a hard impulse to break ;) Thanks for the reminder.

[fitzgen]

Ok, I left a bunch of comments, but they are all very nit picky. Consider it an r=me with comments. I'll merge as soon you update.

Thanks!

[khuey]

If github isn't sending you emails when I overwrite commits, this is ready to merge @fitzgen.

[fitzgen]

Huh, I'm not getting those emails.

[fitzgen]

Thanks again!

[khuey]

np, I'm learning a lot from your reviews :)