can't compile bindings after rustfmt

[ctaggart]

rustfmt returns a exit code of 3. In #1042, it looks like it will treat that as a warning. However, this code will not compile after that. ctaggart/octh#27

Input C/C++ Header

template <typename> class a;
template <typename> struct b;
template <typename c, typename = a<b<c>>> class map {};
class octave_fields {
  class : map<int> {};
};

Bindgen Invocation

#!/usr/bin/env bash
#set -u
export RUST_BACKTRACE=1
clang-3.9 --std=c++11 -c __bindgen.ii

~/rust-bindgen/target/release/bindgen \
    --output __bindgen.rs \
    --enable-cxx-namespaces \
    --whitelist-type octave.* \
    --whitelist-function octave.* \
    --use-core \
    --raw-line "extern crate core;" \
    __bindgen.ii \
    -- -v -x c++ -std=c++11 \
    2>/dev/null
rc=$?; if [[ $rc != 0 ]]; then exit $rc; fi

rustfmt __bindgen.rs 2>/dev/null
rustc --crate-type=lib __bindgen.rs 2>/dev/null

# return success if there is an error code is detected
rc=$?; if [[ $rc != 0 ]]; then exit 0; else exit 1; fi

# time creduce ./bindgen-bug.sh __bindgen.ii

Actual Results

Creates this which compiles:

/* automatically generated by rust-bindgen */

extern crate core;

# [ allow ( non_snake_case , non_camel_case_types , non_upper_case_globals ) ] pub mod root { # [ allow ( unused_imports ) ] use self :: super :: root ; # [ repr ( C ) ] # [ derive ( Debug , Copy , Clone ) ] pub struct c { pub _address : u8 , } # [ repr ( C ) ] # [ derive ( Copy ) ] pub struct e { pub __bindgen_anon_1 : root :: e__bindgen_ty_1 , } # [ repr ( C ) ] # [ derive ( Copy ) ] pub union e__bindgen_ty_1 { pub d : [ :: std :: os :: raw :: c_char ; 4usize ] , _bindgen_union_align : [ u8 ; 4usize ] , } # [ test ] fn bindgen_test_layout_e__bindgen_ty_1 ( ) { assert_eq ! ( :: core :: mem :: size_of :: < e__bindgen_ty_1 > ( ) , 4usize , concat ! ( "Size of: " , stringify ! ( e__bindgen_ty_1 ) ) ) ; assert_eq ! ( :: core :: mem :: align_of :: < e__bindgen_ty_1 > ( ) , 1usize , concat ! ( "Alignment of " , stringify ! ( e__bindgen_ty_1 ) ) ) ; assert_eq ! ( unsafe { & ( * ( 0 as * const e__bindgen_ty_1 ) ) . d as * const _ as usize } , 0usize , concat ! ( "Alignment of field: " , stringify ! ( e__bindgen_ty_1 ) , "::" , stringify ! ( d ) ) ) ; } impl Clone for e__bindgen_ty_1 { fn clone ( & self ) -> Self { * self } } # [ test ] fn bindgen_test_layout_e ( ) { assert_eq ! ( :: core :: mem :: size_of :: < e > ( ) , 4usize , concat ! ( "Size of: " , stringify ! ( e ) ) ) ; assert_eq ! ( :: core :: mem :: align_of :: < e > ( ) , 1usize , concat ! ( "Alignment of " , stringify ! ( e ) ) ) ; } impl Clone for e { fn clone ( & self ) -> Self { * self } } # [ repr ( C ) ] # [ derive ( Copy , Clone ) ] pub struct B { pub f : root :: e , } # [ repr ( C ) ] # [ derive ( Copy , Clone ) ] pub struct g { pub h : root :: B , } # [ repr ( C ) ] # [ derive ( Copy , Clone ) ] pub struct a { pub _base : root :: g , } # [ repr ( C ) ] # [ derive ( Debug , Copy , Clone ) ] pub struct i { pub _address : u8 , } # [ repr ( C ) ] # [ derive ( Copy ) ] pub struct octave_fields { pub __bindgen_anon_1 : root :: octave_fields__bindgen_ty_1 , } # [ repr ( C ) ] # [ derive ( Copy ) ] pub struct octave_fields__bindgen_ty_1 { pub _address : u8 , } # [ test ] fn bindgen_test_layout_octave_fields__bindgen_ty_1 ( ) { assert_eq ! ( :: core :: mem :: size_of :: < octave_fields__bindgen_ty_1 > ( ) , 1usize , concat ! ( "Size of: " , stringify ! ( octave_fields__bindgen_ty_1 ) ) ) ; assert_eq ! ( :: core :: mem :: align_of :: < octave_fields__bindgen_ty_1 > ( ) , 1usize , concat ! ( "Alignment of " , stringify ! ( octave_fields__bindgen_ty_1 ) ) ) ; } impl Clone for octave_fields__bindgen_ty_1 { fn clone ( & self ) -> Self { * self } } # [ test ] fn bindgen_test_layout_octave_fields ( ) { assert_eq ! ( :: core :: mem :: size_of :: < octave_fields > ( ) , 1usize , concat ! ( "Size of: " , stringify ! ( octave_fields ) ) ) ; assert_eq ! ( :: core :: mem :: align_of :: < octave_fields > ( ) , 1usize , concat ! ( "Alignment of " , stringify ! ( octave_fields ) ) ) ; } impl Clone for octave_fields { fn clone ( & self ) -> Self { * self } } # [ test ] fn __bindgen_test_layout_i_open0_c_open1_char_a_open2_char_close2_close1_close0_instantiation ( ) { assert_eq ! ( :: core :: mem :: size_of :: < root :: i > ( ) , 1usize , concat ! ( "Size of template specialization: " , stringify ! ( root :: i ) ) ) ; assert_eq ! ( :: core :: mem :: align_of :: < root :: i > ( ) , 1usize , concat ! ( "Alignment of template specialization: " , stringify ! ( root :: i ) ) ) ; } }

Run rustfmt on it returns an exit code of 3:

$ rustfmt __bindgen.rs
Rustfmt failed at /home/cameron/octh/__bindgen.rs:132: line exceeded maximum length (maximum: 100, found: 109) (sorry)

$ echo $?
3

And now it no longer compiles:

$ rustc --crate-type=lib __bindgen.rs
error: incorrect close delimiter: `]`
  --> __bindgen.rs:20:29
   |
20 |     #[derive(Copy)]; 4usize ] , }    #[test]
   |                             ^
   |
note: unclosed delimiter
  --> __bindgen.rs:6:14
   |
6  | pub mod root {
   |              ^

error: unexpected close delimiter: `}`
  --> __bindgen.rs:20:33
   |
20 |     #[derive(Copy)]; 4usize ] , }    #[test]
   | 

/* automatically generated by rust-bindgen */

extern crate core;

#[allow(non_snake_case, non_camel_case_types, non_upper_case_globals)]
pub mod root {
    #[allow(unused_imports)]
    use self::super::root;
    #[repr(C)]
    #[derive(Debug, Copy, Clone)]
    pub struct c {
        pub _address: u8,
    }
    #[repr(C)]
    #[derive(Copy)]
    pub struct e {
        pub __bindgen_anon_1: root::e__bindgen_ty_1,
    }
    #[repr(C)]
    #[derive(Copy)]; 4usize ] , }    #[test]
    fn bindgen_test_layout_e__bindgen_ty_1() {
        assert_eq!(
            ::core::mem::size_of::<e__bindgen_ty_1>(),
            4usize,
            concat!("Size of: ", stringify!(e__bindgen_ty_1))
        );
        assert_eq!(
            ::core::mem::align_of::<e__bindgen_ty_1>(),
            1usize,
            concat!("Alignment of ", stringify!(e__bindgen_ty_1))
        );
        assert_eq!(
            unsafe { &(*(0 as *const e__bindgen_ty_1)).d as *const _ as usize },
            0usize,
            concat!(
                "Alignment of field: ",
                stringify!(e__bindgen_ty_1),
                "::",
                stringify!(d)
            )
        );
    }
    impl Clone for e__bindgen_ty_1 {
        fn clone(&self) -> Self {
            *self
        }
    }
    #[test]
    fn bindgen_test_layout_e() {
        assert_eq!(
            ::core::mem::size_of::<e>(),
            4usize,
            concat!("Size of: ", stringify!(e))
        );
        assert_eq!(
            ::core::mem::align_of::<e>(),
            1usize,
            concat!("Alignment of ", stringify!(e))
        );
    }
    impl Clone for e {
        fn clone(&self) -> Self {
            *self
        }
    }
    #[repr(C)]
    #[derive(Copy, Clone)]
    pub struct B {
        pub f: root::e,
    }
    #[repr(C)]
    #[derive(Copy, Clone)]
    pub struct g {
        pub h: root::B,
    }
    #[repr(C)]
    #[derive(Copy, Clone)]
    pub struct a {
        pub _base: root::g,
    }
    #[repr(C)]
    #[derive(Debug, Copy, Clone)]
    pub struct i {
        pub _address: u8,
    }
    #[repr(C)]
    #[derive(Copy)]
    pub struct octave_fields {
        pub __bindgen_anon_1: root::octave_fields__bindgen_ty_1,
    }
    #[repr(C)]
    #[derive(Copy)]
    pub struct octave_fields__bindgen_ty_1 {
        pub _address: u8,
    }
    #[test]
    fn bindgen_test_layout_octave_fields__bindgen_ty_1() {
        assert_eq!(
            ::core::mem::size_of::<octave_fields__bindgen_ty_1>(),
            1usize,
            concat!("Size of: ", stringify!(octave_fields__bindgen_ty_1))
        );
        assert_eq!(
            ::core::mem::align_of::<octave_fields__bindgen_ty_1>(),
            1usize,
            concat!("Alignment of ", stringify!(octave_fields__bindgen_ty_1))
        );
    }
    impl Clone for octave_fields__bindgen_ty_1 {
        fn clone(&self) -> Self {
            *self
        }
    }
    #[test]
    fn bindgen_test_layout_octave_fields() {
        assert_eq!(
            ::core::mem::size_of::<octave_fields>(),
            1usize,
            concat!("Size of: ", stringify!(octave_fields))
        );
        assert_eq!(
            ::core::mem::align_of::<octave_fields>(),
            1usize,
            concat!("Alignment of ", stringify!(octave_fields))
        );
    }
    impl Clone for octave_fields {
        fn clone(&self) -> Self {
            *self
        }
    }
    #[test]fn __bindgen_test_layout_i_open0_c_open1_char_a_open2_char_close2_close1_close0_instantiation ( ){
        assert_eq!(
            ::core::mem::size_of::<root::i>(),
            1usize,
            concat!("Size of template specialization: ", stringify!(root::i))
        );
        assert_eq!(
            ::core::mem::align_of::<root::i>(),
            1usize,
            concat!(
                "Alignment of template specialization: ",
                stringify!(root::i)
            )
        );
    }
}

Expected Results

bindgen errors when rustfmt errors. And may be we simple expect rustfmt to not error in this case and log a bug there.

[ctaggart]

If I install rustfmt-nightly instead, it works. The downside is that it requires rust nightly.

[fitzgen]

If I install rustfmt-nightly instead, it works. The downside is that it requires rust nightly.

Yeah, it's unfortunate, but the rustfmt package is deprecated in favor of rustfmt-nightly :-/

[felixrabe]

Mentioned on https://news.ycombinator.com/item?id=17314968 and might need to be re-opened.