Rust 1.18 regression, rotor-http-0.6.0

[brson]

http://github.com/tailhook/rotor-http

brian@ip-10-145-43-250:~/dev/rotor-http⟫ git log -1
commit 191533f231da831da3c25325c60d2da50b7d7852
Author: Paul Colomiets <paul@colomiets.name>
Date:   Tue Mar 1 23:35:37 2016 +0200

    Upgrade rotor to v0.6.0, bump version to v0.6.0

brian@ip-10-145-43-250:/mnt2/dev⟫ rustc +beta -Vv
rustc 1.18.0-beta.1 (4dce67253 2017-04-25)
binary: rustc
commit-hash: 4dce67253d67785c74c8d270c38d774edd0deed8
commit-date: 2017-04-25
host: x86_64-unknown-linux-gnu
release: 1.18.0-beta.1
LLVM version: 3.9

   Compiling matches v0.1.4
   Compiling nix v0.5.1
   Compiling net2 v0.2.26
   Compiling kernel32-sys v0.2.2
   Compiling slab v0.1.3
   Compiling miow v0.1.5
   Compiling time v0.1.35
   Compiling mio v0.5.1
   Compiling rotor v0.6.3
   Compiling rotor-tools v0.3.2
   Compiling rotor-test v0.1.0
   Compiling rotor-stream v0.5.1
   Compiling rotor-http v0.6.0 (file:///mnt2/dev/rotor-http)
warning: private type `server::parser::test::Context` in public interface (error E0446)
   --> src/server/parser.rs:705:9
    |
705 |         type Context = Context;
    |         ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: #[warn(private_in_public)] on by default
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #34537 <https://github.com/rust-lang/rust/issues/34537>

    Finished dev [unoptimized + debuginfo] target(s) in 20.23 secs
     Running target/debug/deps/rotor_http-8fbeafb96417714c

running 19 tests
test headers::test::test_chunked ... ok
test headers::test::test_close ... ok
test headers::test::test_connection ... ok
test headers::test::test_content_len ... ok
test headers::test::test_continue ... ok
test headers::test::test_expect ... ok
test message::test::message_size ... ok
test message::test::minimal_request ... ok
test message::test::minimal_response ... ok
test message::test::close_response11 ... ok
test headers::test::test_transfer_encoding ... ok
test message::test::minimal_response11 ... ok
test server::parser::test::parser_size ... FAILED
test server::parser::test::test_one_chunk ... ok
test server::parser::test::test_empty_chunked ... ok
test server::parser::test::test_chunked_encoding ... ok
test server::parser::test::test_partial_headers ... ok
test server::parser::test::test_zero_body ... ok
test server::parser::test::test_progressive_chunked ... ok

failures:

---- server::parser::test::parser_size stdout ----
        thread 'server::parser::test::parser_size' panicked at 'assertion failed: `(left == right)` (left: `80`, right: `88`)', src/server/parser.rs:750
note: Run with `RUST_BACKTRACE=1` for a backtrace.


failures:
    server::parser::test::parser_size

test result: FAILED. 18 passed; 1 failed; 0 ignored; 0 measured

error: test failed, to rerun pass '--lib'

cc @tailhook

[brson]

By the name of the test maybe this is checking something exact about the ABI.

[kennytm]

It is testing the mem::size_of of a structure. Broken by struct field reordering I guess. The RHS is actually already changed from 88 to 80 last year.

tailhook/rotor-http@f86e442#diff-b195878d7b1f805e376168d3d3039ef3L701

[arielb1]

Why did struct field reordering make things increase in size?

[kennytm]

@arielb1 The test was checking assert_eq!(size_of::<Parser>(), 88), and the LHS is reduced to 80 in beta.

[arielb1]

@kennytm

Missed that we're talking about 0.6.0 rather than the most recent 0.7.0. In that case, smaller structs are better, aren't they?

[kennytm]

@arielb1 This should be an expected implementation breakage.