diesel_codegen fails to compile on latest nightly

[shssoichiro]

On the latest nightly, rustc 1.10.0-nightly (5ebe41835 2016-05-15), attempting to compile diesel_codegen with the following Cargo.toml:

diesel = { git = "https://github.com/diesel-rs/diesel.git" }
diesel_codegen = { version = "^0.6.0", default-features = false, features = ["nightly", "postgres"] }

Results in the following compile errors:

   Compiling diesel_codegen v0.6.1
/Users/joshuaholmer/.cargo/registry/src/github.com-1ecc6299db9ec823/diesel_codegen-0.6.1/src/insertable.rs:86:46: 86:54 error: no associated item named `empty` found for type `syntax::ptr::P<_>` in the current scope
/Users/joshuaholmer/.cargo/registry/src/github.com-1ecc6299db9ec823/diesel_codegen-0.6.1/src/insertable.rs:86         cx.typaram(span, str_to_ident("DB"), P::empty(), None),
                                                                                                                                                           ^~~~~~~~
/Users/joshuaholmer/.cargo/registry/src/github.com-1ecc6299db9ec823/diesel_codegen-0.6.1/src/insertable.rs:86:46: 86:54 note: in this expansion of vec! (defined in <std macros>)
/Users/joshuaholmer/.cargo/registry/src/github.com-1ecc6299db9ec823/diesel_codegen-0.6.1/src/insertable.rs:86:46: 86:54 note: in this expansion of vec! (defined in <std macros>)
/Users/joshuaholmer/.cargo/registry/src/github.com-1ecc6299db9ec823/diesel_codegen-0.6.1/src/insertable.rs:86:46: 86:54 note: in this expansion of include!
/Users/joshuaholmer/.cargo/registry/src/github.com-1ecc6299db9ec823/diesel_codegen-0.6.1/src/queryable.rs:64:42: 64:50 error: no associated item named `empty` found for type `syntax::ptr::P<_>` in the current scope
/Users/joshuaholmer/.cargo/registry/src/github.com-1ecc6299db9ec823/diesel_codegen-0.6.1/src/queryable.rs:64     cx.typaram(span, str_to_ident(name), P::empty(), None)
                                                                                                                                                      ^~~~~~~~
/Users/joshuaholmer/.cargo/registry/src/github.com-1ecc6299db9ec823/diesel_codegen-0.6.1/src/queryable.rs:64:42: 64:50 note: in this expansion of include!

[sgrif]

Dup of #317 #313

Fixed by #312

We will be releasing 0.7 soon, please be patient. In the mean time I recommend using the version of nightly specified in the .travis.yml file on v0.6.1