blink_k20 fails to build

[plasticchris]

The read me at the root indicates to use the makefile to build; this doesn't work:

chris:zinc chrisjohnson$ EXAMPLE_NAME=blink_k20 make build
cd .
cargo build --example blink_k20 --release --target=thumbv7em-none-eabi --verbose --features mcu_k20
 Downloading num v0.1.27
 Downloading expectest v0.3.1
no example target named `blink_k20`
make: *** [target/thumbv7em-none-eabi/release/examples/blink_k20] Error 101

Further reading indicated I needed to 'care build' in the example directory, which initially failed due to my rust environment being stable, tried beta with the same error, so I tried nightly and got this new error:

chris:blink_k20 chrisjohnson$ cargo build
   Compiling ioreg v0.1.0 (file:///Users/chrisjohnson/zinc/examples/blink_k20)
   Compiling core v1.0.0 (https://github.com/hackndev/rust-libcore#d9dc4f94)
/Users/chrisjohnson/zinc/ioreg/src/builder/union.rs:179:22: 179:36 error: `ast::StructDef` does not name a structure [E0422]
/Users/chrisjohnson/zinc/ioreg/src/builder/union.rs:179     let struct_def = ast::StructDef {
                                                                             ^~~~~~~~~~~~~~
/Users/chrisjohnson/zinc/ioreg/src/builder/union.rs:179:22: 179:36 help: run `rustc --explain E0422` to see a detailed explanation
/Users/chrisjohnson/zinc/ioreg/src/builder/register.rs:166:13: 166:34 error: unresolved name `ast::TupleVariantKind` [E0425]
/Users/chrisjohnson/zinc/ioreg/src/builder/register.rs:166       kind: ast::TupleVariantKind(Vec::new()),
                                                                       ^~~~~~~~~~~~~~~~~~~~~
/Users/chrisjohnson/zinc/ioreg/src/builder/register.rs:166:13: 166:34 help: run `rustc --explain E0425` to see a detailed explanation
error: aborting due to 2 previous errors

It looks like some issue with ioreg?

[farcaller]

Structs broke down in fun and unexpected way apparently, opened a PR to track a fix.

[farcaller]

fixed in #351