Derive fails for macro-generated struct

[rsaarelm]

Script to reproduce:

#!/bin/bash

cargo new struct-macro-bug
cd struct-macro-bug

cat > Cargo.toml <<'EOF'
[package]
name = "serde-bug"
version = "0.1.0"

[dependencies]
serde = "0.8"
serde_derive = "0.8"
EOF

cat > src/lib.rs <<'EOF'
#![feature(proc_macro)]

extern crate serde;
#[macro_use]
extern crate serde_derive;

#[derive(Serialize, Deserialize)]
pub struct ComponentData<C> {
    _data: C,
}

macro_rules! Struct {
    {
        $($compname:ident: $comptype:ty,)+
    } => {
        #[derive(Serialize, Deserialize)]
        pub struct _ComponentStore {
            $(pub $compname: $crate::ComponentData<$comptype>),+
        }
    }
}

#[cfg(test)]
mod tests {
    #[derive(Serialize, Deserialize)]
    pub struct X;

    Struct!{a: X,}
    #[test]
    fn it_works() {
    }
}
EOF

cargo test
rustc --version

Output:

     Created library `struct-macro-bug` project
    Updating registry `https://github.com/rust-lang/crates.io-index`
   Compiling unicode-xid v0.0.3
   Compiling quote v0.3.5
   Compiling serde v0.8.17
   Compiling syn v0.9.2
   Compiling serde_codegen_internals v0.10.0
   Compiling post-expansion v0.1.0
   Compiling serde_codegen v0.8.17
   Compiling serde_derive v0.8.17
   Compiling serde-bug v0.1.0 (file:///home/rsaarelm/scratch/serde-bug/struct-macro-bug)
error: custom derive attribute panicked
  --> src/lib.rs:16:18
   |
16 |         #[derive(Serialize, Deserialize)]
   |                  ^^^^^^^^^
...
28 |     Struct!{a: X,}
   |     -------------- in this macro invocation
   |
   = help: message: called `Result::unwrap()` on an `Err` value: "failed to parse macro input: \"#[derive(Serialize)]\\n#[derive(Deserialize)]\\npub struct _ComponentStore {\\n    pub a: $crate::ComponentData<X>,\\n}\\n\""

Build failed, waiting for other jobs to finish...
error: Could not compile `serde-bug`.

To learn more, run the command again with --verbose.
rustc 1.14.0-nightly (cae6ab1c4 2016-11-05)

[dtolnay]

Thanks for the script! This is a Rust bug. I minimized it some more and opened rust-lang/rust#37637.

[rsaarelm]

Thanks! I'll try to get back here when the fix has landed in nightly and I've tried it.

[dtolnay]

The fix merged into Rust. I am leaving this issue open until you or I confirm the fix.

[dtolnay]

This is fixed in serde 0.8.18 and rustc 1.15.0-nightly (ac635aa95 2016-11-18).

     Created library `struct-macro-bug` project
    Updating registry `https://github.com/rust-lang/crates.io-index`
 Downloading serde_derive v0.8.18
   Compiling unicode-xid v0.0.3
   Compiling serde v0.8.18
   Compiling quote v0.3.5
   Compiling syn v0.10.3
   Compiling serde_codegen_internals v0.11.1
   Compiling serde_codegen v0.8.18
   Compiling serde_derive v0.8.18
   Compiling serde-bug v0.1.0
    Finished debug [unoptimized + debuginfo] target(s) in 14.30 secs
     Running target/debug/deps/serde_bug-cc3a865be4a1ef0c

running 1 test
test tests::it_works ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured

   Doc-tests serde-bug

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured

rustc 1.15.0-nightly (ac635aa95 2016-11-18)