mac-0.1.0 fails test suite due to type inference regression in Rust 1.15 #39808

brson · 2017-02-14T05:02:22Z

   Doc-tests mac

running 12 tests
test format_if_0 ... FAILED
test do_while_1 ... ok
test addrs_of_0 ... ok
test do_while_0 ... ok
test inspect_1 ... ignored
test if_cfg_0 ... ok
test if_cfg_1 ... ok
test match_cfg_0 ... ok
test inspect_0 ... ok
test matches_0 ... ok
test unwrap_or_return_0 ... ok
test test_eq_0 ... ok

failures:

---- format_if_0 stdout ----
        error[E0283]: type annotations required: cannot resolve `_: std::borrow::ToOwned`
  --> <anon>:11:21
   |
11 |   let not_formatted = format_if!(false, "Vague error", "Error code {:?}", {
   |  _____________________^ starting here...
12 | |     // Note that the argument is not evaluated.
13 | |     panic!("oops");
14 | | });
   | |__^ ...ending here
   |
   = note: required by `std::borrow::Cow::Owned`
   = note: this error originates in a macro outside of the current crate

error: aborting due to previous error(s)

thread 'format_if_0' panicked at 'Box<Any>', /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/librustc/session/mod.rs:201
note: Run with `RUST_BACKTRACE=1` for a backtrace.
https://github.com/reem/rust-mac dcc9155e9d23a81e92e325899d4b6bed098bcded

failures:
    format_if_0

test result: FAILED. 10 passed; 1 failed; 1 ignored; 0 measured

error: test failed

This is on 1.15. Not 1.14.

cc @reem

The text was updated successfully, but these errors were encountered:

nagisa · 2017-02-14T14:54:20Z

Likely #39440? This is not considered a breakage.

Actionable items: send PR to the crate or inform the author of the issue.

durka · 2017-02-14T15:36:53Z

Merged 10 days ago and it's in stable already?

nagisa · 2017-02-14T15:41:54Z

Oh well, then whatever other new impl for Cow?

durka · 2017-02-14T18:48:38Z

Yeah. Why wasn't this caught during the beta period though?

durka · 2017-02-14T18:52:10Z

It's actually because of the never-type stuff. The type error is complaining about a block that says { panic!(); }. Annotating the type as Cow<str> fixes it.

durka · 2017-02-14T18:58:34Z

Minimized:

use std::borrow::Cow;

fn main() {
    let _ = if false {
        Cow::Owned(format!("{:?}", panic!())) /* as Cow<str> */ // uncomment to fix
    } else {
        Cow::Borrowed("")
    };
}

nagisa · 2017-02-15T17:47:31Z

Oh wow, this sounds nasty. Especially since typeck shouldn’t even bother figuring out the type of the branch with panic!() in it.

nikomatsakis · 2017-03-02T01:14:23Z

This is because of #39485, where we updated our handling of diverging types to be more consistent.

nikomatsakis · 2017-03-02T01:15:42Z

Oh, well, it says stable-to-stable, so I guess not. But yes, related to the handling of diverging types.

nikomatsakis · 2017-03-02T01:16:57Z

cc @eddyb @canndrew

nikomatsakis · 2017-03-02T23:34:53Z

Even smaller example:

fn main() {
    let _ = if false {
        Ok(panic!())
    } else {
        Err("")
    };
}

nikomatsakis · 2017-03-02T23:35:10Z

triage: P-high

along with #39984

The new strategy is as follows. First, the `!` type is assigned in two cases: - a block with a diverging statement and no tail expression (e.g., `{return;}`); - any expression with the type `!` is considered diverging. Second, we track when we are in a diverging state, and we permit a value of any type to be coerced **into** `!` if the expression that produced it is diverging. This means that `fn foo() -> ! { panic!(); 22 }` type-checks, even though the block has a type of `usize`. Finally, coercions **from** the `!` type to any other are always permitted. Fixes rust-lang#39808.

Fixes rust-lang#39808

The new strategy is as follows. First, the `!` type is assigned in two cases: - a block with a diverging statement and no tail expression (e.g., `{return;}`); - any expression with the type `!` is considered diverging. Second, we track when we are in a diverging state, and we permit a value of any type to be coerced **into** `!` if the expression that produced it is diverging. This means that `fn foo() -> ! { panic!(); 22 }` type-checks, even though the block has a type of `usize`. Finally, coercions **from** the `!` type to any other are always permitted. Fixes rust-lang#39808.

Fixes rust-lang#39808

change the strategy for diverging types The new strategy is as follows. First, the `!` type is assigned in two cases: - a block with a diverging statement and no tail expression (e.g., `{return;}`); - any expression with the type `!` is considered diverging. Second, we track when we are in a diverging state, and we permit a value of any type to be coerced **into** `!` if the expression that produced it is diverging. This means that `fn foo() -> ! { panic!(); 22 }` type-checks, even though the block has a type of `usize`. Finally, coercions **from** the `!` type to any other are always permitted. Fixes rust-lang#39808. Fixes rust-lang#39984.

The new strategy is as follows. First, the `!` type is assigned in two cases: - a block with a diverging statement and no tail expression (e.g., `{return;}`); - any expression with the type `!` is considered diverging. Second, we track when we are in a diverging state, and we permit a value of any type to be coerced **into** `!` if the expression that produced it is diverging. This means that `fn foo() -> ! { panic!(); 22 }` type-checks, even though the block has a type of `usize`. Finally, coercions **from** the `!` type to any other are always permitted. Fixes rust-lang#39808.

Fixes rust-lang#39808

change the strategy for diverging types The new strategy is as follows. First, the `!` type is assigned in two cases: - a block with a diverging statement and no tail expression (e.g., `{return;}`); - any expression with the type `!` is considered diverging. Second, we track when we are in a diverging state, and we permit a value of any type to be coerced **into** `!` if the expression that produced it is diverging. This means that `fn foo() -> ! { panic!(); 22 }` type-checks, even though the block has a type of `usize`. Finally, coercions **from** the `!` type to any other are always permitted. Fixes #39808. Fixes #39984.

The new strategy is as follows. First, the `!` type is assigned in two cases: - a block with a diverging statement and no tail expression (e.g., `{return;}`); - any expression with the type `!` is considered diverging. Second, we track when we are in a diverging state, and we permit a value of any type to be coerced **into** `!` if the expression that produced it is diverging. This means that `fn foo() -> ! { panic!(); 22 }` type-checks, even though the block has a type of `usize`. Finally, coercions **from** the `!` type to any other are always permitted. Fixes rust-lang#39808.

Fixes rust-lang#39808

brson added the regression-from-stable-to-stable Performance or correctness regression from one stable version to another. label Feb 14, 2017

durka mentioned this issue Feb 14, 2017

fix format_if for rustc 1.15 reem/rust-mac#13

Merged

golddranks mentioned this issue Feb 20, 2017

Type inference regression in recent nightly #39984

Closed

brson added I-nominated T-lang Relevant to the language team, which will review and decide on the PR/issue. labels Mar 2, 2017

rust-highfive added P-high High priority and removed I-nominated labels Mar 2, 2017

nikomatsakis self-assigned this Mar 2, 2017

nikomatsakis mentioned this issue Mar 3, 2017

change the strategy for diverging types #40224

Merged

brson added the A-typesystem Area: The type system label Mar 9, 2017

nikomatsakis mentioned this issue Mar 18, 2017

Revert #39485, fixing type-inference regressions #40636

Merged

nikomatsakis added a commit to nikomatsakis/rust that referenced this issue Mar 18, 2017

add regression test for rust-lang#39808

93962af

Fixes rust-lang#39808

nikomatsakis added a commit to nikomatsakis/rust that referenced this issue Mar 25, 2017

add regression test for rust-lang#39808

692156f

Fixes rust-lang#39808

nikomatsakis added a commit to nikomatsakis/rust that referenced this issue Mar 30, 2017

add regression test for rust-lang#39808

f11b7d3

Fixes rust-lang#39808

bors closed this as completed in #40224 Mar 30, 2017

michaelwoerister pushed a commit to michaelwoerister/rust that referenced this issue Apr 7, 2017

add regression test for rust-lang#39808

1cfd9b6

Fixes rust-lang#39808

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mac-0.1.0 fails test suite due to type inference regression in Rust 1.15 #39808

mac-0.1.0 fails test suite due to type inference regression in Rust 1.15 #39808

brson commented Feb 14, 2017

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mac-0.1.0 fails test suite due to type inference regression in Rust 1.15 #39808

mac-0.1.0 fails test suite due to type inference regression in Rust 1.15 #39808

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brson commented Feb 14, 2017

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