Swap return value order in pipes::oneshot

[brson]

oneshot returns (ChanOne, PortOne) while stream returns (Port, Chan). I prefer the port to be first.

[nickdesaulniers]

I'd like to try my hand at this, as my first contribution.

[brson]

@nickdesaulniers Great!

[nickdesaulniers]

So I'm not too sure about this test:
https://github.com/mozilla/rust/blob/master/src/libcore/pipes.rs#L1259
@pcwalton was unsure where init came from, due to this syntax (which fully eludes me):
https://github.com/mozilla/rust/blob/master/src/libcore/pipes.rs#L1183

I've modified the order in the function declaration, and am still working through the resulting regressions, but I feel like this is a relic that should get fixed with this bug. EDIT: where can I find the init function of the oneshot module to modify it?

[brson]

The init function is generated by the pipes protocol compiler, specifically the gen_init method.

I would consider these two separate issues (oneshot vs. init) as modifying the codegen for init will run into self-hosting issues, forcing you to come up with a scheme to transition from the old definition to the new. The problem you will hit is that the snapshot (stage0) compiler will generate code that calls into core::pipes and code in core::pipes will call into code generated by the protocol compiler, but because you are modifying core::pipes the two will not agree on the definitions in use. Please do take a crack at it and see what kind of problems you run into - I can help you come up with a transition strategy.

For what it's worth I use two basic strategies for working around self-hosting problems:

• Leave the old definitions and duplicate them with a new definition; make a snapshot; remove the old definition; duplicate the new definition with the name of the old definition; make a snapshot; delete the duplicate definition
• Add #[cfg(stage0)], #[cfg(stage1)], etc. attributes to code to make it compile differently in each stage of compilation; snapshot; remove the #[cfg(stage0)] definition

There's some outdated information about the bootstrapping process here: https://github.com/mozilla/rust/wiki/Note-compiler-snapshots

[nickdesaulniers]

Should I make that a separate issue and post line numbers containing all incorrect references? I have them all from $ ack --type-add=rust=.rs,.rc oneshot::init

[brson]

Yes, that would be great. Thanks.

[nickdesaulniers]

tests are green. Pull request inbound

[brson]

Fixed!