Implement dependency information output like GCC to rustc

[omasanori]

Dependency information from compilers is useful to build incrementally. Without that, build process will be incorrect and/or slow.

GCC and Clang can emit such information in (a subset of) Makefile syntax. AFAIK that can be used from make (of cource) and ninja. It might be nice if rustc provides similar feature, I think.

[emberian]

dup of #2369 and #558, closing (complain if you disagree)

[huonw]

I'm reopening this because I think this is worth a separate issue, since file dependencies (detecting when a recompile is needed) is different to function dependencies and incremental recompilation. I could imagine this being a subtool of rust e.g. rust deps --format=make my_crate.rs.

That said, rustpkg is designed to be a universal build tool for Rust code, so this may not be a useful/desired tool (I'll let someone else make this decision).

[catamorphism]

No plans to support Makefile syntax -- the focus is on rustpkg and #2369 and #558 capture what would be desirable to implement. Closing as dup.

[omasanori]

I'm sorry to be unaware of duplication. I think it's nice to get rustpkg faster first, thus I'm happy with the direction.

However I doubt whether rustpkg suitable for every areas where Rust will be used. I'll use rustpkg and reopen this when I really need dependency export.

[huonw]

@omasanori It's actually not that hard to do (or at least, an approximation to it) as an external binary, since the parser is a normal crate (called syntax) that you can import with extern mod. e.g. the following prints a list of files that a given file imports via a mod statement. (Don't treat it is a model of good Rust code though, it's definitely not.)

extern mod syntax;
extern mod extra;
use std::hashmap::HashSet;
use syntax::{parse, visit};

fn main() {
    let filename = match std::os::args() {
        [_, name] => name,
        _ => {
            println("Expected the file path");
            fail!()
        }
    };
    let path = Path(filename);

    let parsesess = parse::new_parse_sess(None);
    let mut crate = parse::parse_crate_from_file(&path, ~[], parsesess);
    crate = syntax::ext::expand::expand_crate(parsesess, ~[], crate);

    let files = @mut HashSet::new();
    let visitor = visit::mk_vt(@visit::Visitor {
        visit_mod: |m, sp, id, tup| {
            let fname = parsesess.cm.span_to_filename(sp);
            if "<core-macros>" != fname {
                (*files).insert(fname);
            }
            visit::visit_mod(m, sp, id, tup)
        },
        .. *visit::default_visitor()
    });

    visit::visit_crate(crate, ((), visitor));

    let mut v = ~[];
    do files.consume |s| { v.push(s); }
    extra::sort::tim_sort(v);

    println(v.connect(" "));
}

~/rust/src/libextra $ ~/rust-mk extra.rs
arc.rs bitv.rs c_vec.rs comm.rs crypto/sha1.rs crypto/sha2.rs dbg.rs deque.rs dlist.rs ebml.rs extra.rs fileinput.rs flate.rs flatpipes.rs future.rs getopts.rs json.rs list.rs net_ip.rs net_tcp.rs net_url.rs num/bigint.rs num/complex.rs num/rational.rs priority_queue.rs rc.rs rl.rs rope.rs smallintmap.rs sort.rs stats.rs sync.rs tempfile.rs term.rs terminfo/parm.rs terminfo/parser/compiled.rs terminfo/terminfo.rs test.rs time.rs timer.rs treemap.rs unicode.rs uv_global_loop.rs uv_ll.rs

[omasanori]

@huonw Thank you for your suggestion. I just remember what LLVM people said: make it as a set of modular library, and we will be happy. 😃

[metajack]

I'm working on this.

[omasanori]

@metajack I really appreciate your work. Thank you!