Can't compile brotli with rustc 1.27.0-nightly (2f2a11dfc 2018-05-16)

[nox]

error[E0277]: the trait bound `u64: core::slice::SliceIndex<[HistogramType]>` is not satisfied
   --> /Users/nox/.cargo/registry/src/github.com-1ecc6299db9ec823/brotli-1.1.2/src/enc/block_splitter.rs:271:26
    |
271 |   let data_size: usize = histograms[0].slice().len();
    |                          ^^^^^^^^^^^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `core::slice::SliceIndex<[HistogramType]>` is not implemented for `u64`
    = note: required because of the requirements on the impl of `core::ops::Index<u64>` for `[HistogramType]`

error[E0277]: the trait bound `u64: core::slice::SliceIndex<[f32]>` is not satisfied
   --> /Users/nox/.cargo/registry/src/github.com-1ecc6299db9ec823/brotli-1.1.2/src/enc/block_splitter.rs:341:13
    |
341 |             (*cost_iter).0[sub_index] += local_insert_cost[sub_index];
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `core::slice::SliceIndex<[f32]>` is not implemented for `u64`
    = note: required because of the requirements on the impl of `core::ops::Index<u64>` for `[f32]`

error[E0277]: the trait bound `u64: core::slice::SliceIndex<[f32]>` is not satisfied
   --> /Users/nox/.cargo/registry/src/github.com-1ecc6299db9ec823/brotli-1.1.2/src/enc/block_splitter.rs:341:42
    |
341 |             (*cost_iter).0[sub_index] += local_insert_cost[sub_index];
    |                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `core::slice::SliceIndex<[f32]>` is not implemented for `u64`
    = note: required because of the requirements on the impl of `core::ops::Index<u64>` for `[f32]`

error[E0277]: the trait bound `u64: core::slice::SliceIndex<[f32]>` is not satisfied
   --> /Users/nox/.cargo/registry/src/github.com-1ecc6299db9ec823/brotli-1.1.2/src/enc/block_splitter.rs:342:30
    |
342 |             let final_cost = (*cost_iter).0[sub_index];
    |                              ^^^^^^^^^^^^^^^^^^^^^^^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `core::slice::SliceIndex<[f32]>` is not implemented for `u64`
    = note: required because of the requirements on the impl of `core::ops::Index<u64>` for `[f32]`

error[E0308]: mismatched types
   --> /Users/nox/.cargo/registry/src/github.com-1ecc6299db9ec823/brotli-1.1.2/src/enc/block_splitter.rs:345:45
    |
345 |               *block_id_ptr = (base_index + sub_index) as u8;
    |                                             ^^^^^^^^^ expected usize, found u64

error[E0277]: cannot add `u64` to `usize`
   --> /Users/nox/.cargo/registry/src/github.com-1ecc6299db9ec823/brotli-1.1.2/src/enc/block_splitter.rs:345:43
    |
345 |               *block_id_ptr = (base_index + sub_index) as u8;
    |                                           ^ no implementation for `usize + u64`
    |
    = help: the trait `core::ops::Add<u64>` is not implemented for `usize`

Cc @rust-lang/compiler

[kennytm]

This seems to be related to #47832.

Note that the report mentioned brotli 1.1.2, but latest versions are brotli 2.1.0, 1.2.0 and 1.1.4.

No repro on brotli 2.1.0 with rustc 1.27.0-nightly (f0fdaba04 2018-05-15), let me rustup update and try again.

Edit: Repro on brotli 2.1.0 with rustc 1.27.0-nightly (2f2a11dfc 2018-05-16), bisecting...

---

Note: brotli isn't fully cratered because its Cargo.toml has this line:

[package]
name = "brotli"
# ...
exclude = ["src/bin/testdata/*"]
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

but then the tests cannot be compiled because it relies on those testdata 😒

   Compiling brotli v2.1.0 (file:///$DIR/brotli)
error: couldn't read src/bin/testdata/random_then_unicode: No such file or directory (os error 2)
   --> src/bin/integration_tests.rs:335:46
    |
335 | static RANDOM_THEN_UNICODE : &'static [u8] = include_bytes!("testdata/random_then_unicode");
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...

[Eijebong]

Diesel is affected too

error[E0053]: method `metadata` has an incompatible type for trait
   --> diesel/src/pg/types/array.rs:14:25
    |
14  |     fn metadata(lookup: &PgMetadataLookup) -> PgTypeMetadata {
    |                         ^^^^^^^^^^^^^^^^^ expected associated type, found struct `pg::metadata_lookup::PgMetadataLookup`
    | 
   ::: diesel/src/sql_types/mod.rs:402:25
    |
402 |     fn metadata(lookup: &Self::MetadataLookup) -> Self::TypeMetadata;
    |                         --------------------- type in trait
    |
    = note: expected type `fn(&<pg::backend::Pg as sql_types::TypeMetadata>::MetadataLookup) -> <pg::backend::Pg as sql_types::TypeMetadata>::TypeMetadata`
               found type `fn(&pg::metadata_lookup::PgMetadataLookup) -> pg::backend::PgTypeMetadata`

[kennytm]

Bisection gives #48557 as the regression PR cc @matthewjasper @nikomatsakis

[nagisa]

Diesel issue seems unrelated.

…

On Thu, May 17, 2018, 12:02 Bastien Orivel ***@***.***> wrote: Diesel is affected too error[E0053]: method `metadata` has an incompatible type for trait --> diesel/src/pg/types/array.rs:14:25 | 14 | fn metadata(lookup: &PgMetadataLookup) -> PgTypeMetadata { | ^^^^^^^^^^^^^^^^^ expected associated type, found struct `pg::metadata_lookup::PgMetadataLookup` | ::: diesel/src/sql_types/mod.rs:402:25 | 402 | fn metadata(lookup: &Self::MetadataLookup) -> Self::TypeMetadata; | --------------------- type in trait | = note: expected type `fn(&<pg::backend::Pg as sql_types::TypeMetadata>::MetadataLookup) -> <pg::backend::Pg as sql_types::TypeMetadata>::TypeMetadata` found type `fn(&pg::metadata_lookup::PgMetadataLookup) -> pg::backend::PgTypeMetadata` — You are receiving this because you are on a team that was mentioned. Reply to this email directly, view it on GitHub <#50825 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AApc0nd9guDe4-d0KtEu2_xxXzZNa1PKks5tzTyhgaJpZM4UClUv> .

[nikomatsakis]

Can we verify if the Diesel regression is related or not? cc @sgrif

[matthewjasper]

I'm looking at this.

Minified brotli issue:

fn foo(y: &[()]) where u64: Copy // or From<u64>
{
    let x = y[0]; // u64: std::slice::SliceIndex<[()]>` is not satisfied
}

[matthewjasper]

Minified diesel issue:

trait X {
    type T;
}

trait Y<U>: X {
    fn foo(x: &Self::T);
}

impl X for () {
    type T = ();
}

impl<T> Y<Vec<T>> for () where (): Y<T> {
    fn foo(_x: &()) {}
}

I'll try to get a patch to either fix this or roll back some of the changes in #48557 (more likely) ready tomorrow.