Issue running cargo fix

[theotherphil]

On the imageproc crate https://github.com/PistonDevelopers/imageproc

Creating an issue because the build log told me to:

$ cargo +nightly fix --prepare-for 2018 --all-targets --all-features --allow-dirty
    Checking nodrop v0.1.12
    Checking cfg-if v0.1.2
    Checking memoffset v0.2.1
   Compiling num-traits v0.2.5
    Checking scopeguard v0.3.3
    Checking lazy_static v0.2.11
    Checking libc v0.2.37
   Compiling rayon-core v1.4.0
    Checking void v1.0.2
   Compiling unicode-xid v0.1.0
   Compiling typenum v1.10.0
    Checking lazy_static v1.0.0
   Compiling num-complex v0.2.0
   Compiling matrixmultiply v0.1.14
    Checking adler32 v1.0.2
    Checking regex-syntax v0.4.2
    Checking rustc-serialize v0.3.24
    Checking utf8-ranges v1.0.0
    Checking byteorder v1.2.1
    Checking either v1.4.0
    Checking bitflags v1.0.1
    Checking color_quant v1.0.0
    Checking rawpointer v0.1.0
    Checking lzw v0.10.0
    Checking rand_core v0.2.1
    Checking custom_derive v0.1.7
    Checking approx v0.1.1
    Checking scoped_threadpool v0.1.9
    Checking crossbeam-utils v0.2.2
    Checking log v0.4.1
    Checking arrayvec v0.4.7
    Checking unreachable v1.0.0
    Checking unreachable v0.1.1
   Compiling proc-macro2 v0.4.9
    Checking inflate v0.4.3
    Checking itertools v0.7.6
    Checking memchr v2.0.1
    Checking num_cpus v1.8.0
    Checking rand v0.4.2
    Checking conv v0.3.3
    Checking deflate v0.7.17
    Checking stb_truetype v0.2.2
    Checking gif v0.10.0
    Checking rand v0.5.4
    Checking thread_local v0.3.5
    Checking log v0.3.9
    Checking aho-corasick v0.6.4
    Checking crossbeam-epoch v0.3.0
   Compiling quote v0.6.4
    Checking regex v0.2.6
    Checking crossbeam-deque v0.2.0
   Compiling syn v0.14.5
    Checking generic-array v0.11.1
    Checking rayon v1.0.0
    Checking num-integer v0.1.36
    Checking approx v0.3.0
    Checking num-traits v0.1.43
    Checking ordered-float v0.5.0
    Checking num-iter v0.1.35
    Checking num-bigint v0.1.43
    Checking num-complex v0.1.42
    Checking png v0.12.0
    Checking rusttype v0.5.2
    Checking env_logger v0.4.3
    Checking quickcheck v0.6.1
    Checking alga v0.7.0
    Checking num-rational v0.1.42
    Checking num v0.1.42
    Checking jpeg-decoder v0.1.14
   Compiling num-derive v0.2.2
    Checking nalgebra v0.16.0
    Checking image v0.19.0
    Checking imageproc v0.15.0 (file:///Users/philip/dev/imageproc)
warning: error applying suggestions to `src/drawing/line.rs`

The full error message was:

> Cannot replace slice of data that was already replacedThis likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/cargo/issues
quoting the full output of this command we'd be very appreciative!

      Fixing src/hough.rs (3 fixes)
      Fixing src/drawing/polygon.rs (3 fixes)
      Fixing src/map.rs (1 fix)
      Fixing src/morphology.rs (1 fix)
      Fixing src/filter/mod.rs (6 fixes)
      Fixing src/suppress.rs (5 fixes)
      Fixing src/contrast.rs (5 fixes)
      Fixing src/drawing/conics.rs (3 fixes)
      Fixing src/hog.rs (5 fixes)
      Fixing src/drawing/cross.rs (1 fix)
      Fixing src/drawing/text.rs (2 fixes)
      Fixing src/haar.rs (3 fixes)
      Fixing src/filter/median.rs (4 fixes)
      Fixing src/gradients.rs (4 fixes)
      Fixing src/noise.rs (2 fixes)
      Fixing src/drawing/line.rs (8 fixes)
      Fixing src/drawing/bezier.rs (2 fixes)
      Fixing src/affine.rs (3 fixes)
      Fixing src/distance_transform.rs (4 fixes)
      Fixing src/region_labelling.rs (3 fixes)
      Fixing src/pixelops.rs (2 fixes)
      Fixing src/template_matching.rs (4 fixes)
      Fixing src/edges.rs (5 fixes)
      Fixing src/property_testing.rs (1 fix)
      Fixing src/seam_carving.rs (4 fixes)
      Fixing src/integral_image.rs (5 fixes)
      Fixing src/corners.rs (1 fix)
      Fixing src/drawing/rect.rs (4 fixes)
      Fixing src/stats.rs (1 fix)
warning: absolute paths must start with `self`, `super`, `crate`, or an external crate name in the 2018 edition
 --> src/drawing/line.rs:2:5
  |
2 | use definitions::Image;
  |     ^^^^^^^^^^^^^^^^^^ help: use `crate`: `crate::definitions::Image`
  |
  = note: `-W absolute-paths-not-starting-with-crate` implied by `-W rust-2018-compatibility`
  = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
  = note: for more information, see issue TBD

warning: absolute paths must start with `self`, `super`, `crate`, or an external crate name in the 2018 edition
   --> src/drawing/line.rs:465:13
    |
465 |         use pixelops::interpolate;
    |             ^^^^^^^^^^^^^^^^^^^^^ help: use `crate`: `crate::pixelops::interpolate`
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
    = note: for more information, see issue TBD

warning: absolute paths must start with `self`, `super`, `crate`, or an external crate name in the 2018 edition
   --> src/drawing/line.rs:497:13
    |
497 |         use pixelops::interpolate;
    |             ^^^^^^^^^^^^^^^^^^^^^ help: use `crate`: `crate::pixelops::interpolate`
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
    = note: for more information, see issue TBD

warning: absolute paths must start with `self`, `super`, `crate`, or an external crate name in the 2018 edition
   --> src/drawing/line.rs:524:13
    |
524 |         use pixelops::interpolate;
    |             ^^^^^^^^^^^^^^^^^^^^^ help: use `crate`: `crate::pixelops::interpolate`
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
    = note: for more information, see issue TBD

warning: absolute paths must start with `self`, `super`, `crate`, or an external crate name in the 2018 edition
   --> src/drawing/line.rs:548:21
    |
548 |                   use pixelops::interpolate;
    |                       ^^^^^^^^^^^^^^^^^^^^^ help: use `crate`: `crate::pixelops::interpolate`
...
561 | /     bench_antialiased_lines!(
562 | |         bench_draw_antialiased_line_segment_horizontal,
563 | |         (10, 10), (450, 10)
564 | |     );
    | |______- in this macro invocation
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
    = note: for more information, see issue TBD

warning: absolute paths must start with `self`, `super`, `crate`, or an external crate name in the 2018 edition
   --> src/drawing/line.rs:548:21
    |
548 |                   use pixelops::interpolate;
    |                       ^^^^^^^^^^^^^^^^^^^^^ help: use `crate`: `crate::pixelops::interpolate`
...
566 | /     bench_antialiased_lines!(
567 | |         bench_draw_antialiased_line_segment_vertical,
568 | |         (10, 10), (10, 450)
569 | |     );
    | |______- in this macro invocation
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
    = note: for more information, see issue TBD

warning: absolute paths must start with `self`, `super`, `crate`, or an external crate name in the 2018 edition
   --> src/drawing/line.rs:548:21
    |
548 |                   use pixelops::interpolate;
    |                       ^^^^^^^^^^^^^^^^^^^^^ help: use `crate`: `crate::pixelops::interpolate`
...
571 | /     bench_antialiased_lines!(
572 | |         bench_draw_antialiased_line_segment_diagonal,
573 | |         (10, 10), (450, 450)
574 | |     );
    | |______- in this macro invocation
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
    = note: for more information, see issue TBD

warning: absolute paths must start with `self`, `super`, `crate`, or an external crate name in the 2018 edition
   --> src/drawing/line.rs:548:21
    |
548 |                   use pixelops::interpolate;
    |                       ^^^^^^^^^^^^^^^^^^^^^ help: use `crate`: `crate::pixelops::interpolate`
...
576 | /     bench_antialiased_lines!(
577 | |         bench_draw_antialiased_line_segment_shallow,
578 | |         (10, 10), (450, 80)
579 | |     );
    | |______- in this macro invocation
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
    = note: for more information, see issue TBD

warning: bounds on generic parameters are not enforced in type aliases
  --> src/definitions.rs:16:19
   |
16 | pub type Image<P: Pixel> = ImageBuffer<P, Vec<P::Subpixel>>;
   |                   ^^^^^
   |
   = note: #[warn(type_alias_bounds)] on by default
   = help: the bound will not be checked when the type alias is used, and should be removed
help: use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to associated types in type aliases
  --> src/definitions.rs:16:47
   |
16 | pub type Image<P: Pixel> = ImageBuffer<P, Vec<P::Subpixel>>;
   |                                               ^^^^^^^^^^^

      Fixing src/drawing/line.rs (1 fix)
warning: bounds on generic parameters are not enforced in type aliases
  --> src/definitions.rs:16:19
   |
16 | pub type Image<P: Pixel> = ImageBuffer<P, Vec<P::Subpixel>>;
   |                   ^^^^^
   |
   = note: #[warn(type_alias_bounds)] on by default
   = help: the bound will not be checked when the type alias is used, and should be removed
help: use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to associated types in type aliases
  --> src/definitions.rs:16:47
   |
16 | pub type Image<P: Pixel> = ImageBuffer<P, Vec<P::Subpixel>>;
   |                                               ^^^^^^^^^^^

    Finished dev [unoptimized + debuginfo] target(s) in 46.60s

[alexcrichton]

Thanks so much for the report! Looking at the output here I believe this is a duplicate of #5785 which should be fixed by rust-lang/rust#52720 once it's in nightly.

I'm gonna close this for now, but thanks for filing the bug regardless!