replace `convert::Infallible` with `!` #49038

canndrew · 2018-03-15T04:37:26Z

No description provided.

rust-highfive · 2018-03-15T04:37:37Z

r? @sfackler

(rust_highfive has picked a reviewer for you, use r? to override)

scottmcm

Horray! One step closer to stable TryFrom...

scottmcm · 2018-03-15T05:42:17Z

src/libcore/num/mod.rs

@@ -3595,20 +3595,12 @@ impl fmt::Display for TryFromIntError {
    }
 }

-#[unstable(feature = "try_from", issue = "33417")]
-impl From<Infallible> for TryFromIntError {


Maybe leave this as impl From<!> For TryFromIntError? This is here so that you can use u32: TryFrom<u16> in a method returning Result<_, TryFromIntError>, which I think is still wanted. (Not for those types literally, but for when they're c_whatever aliases.)

I removed it thinking that we'd have impl<T> From<!> for T, but since we won't have that until we have specialization with intersection impls I guess I'd better add it back.

scottmcm · 2018-03-15T05:46:18Z

src/libcore/convert.rs

-/// signals to both the compiler and the user that the error case is impossible.
-#[unstable(feature = "try_from", issue = "33417")]
-#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
-pub enum Infallible {}


Looking through that list of derives, are we missing Copy and Clone for !? They're not in the rustdoc, at least: https://doc.rust-lang.org/nightly/std/primitive.never.html#implementations

(Not a blocker for this PR, of course.)

They're implemented. No idea why they're not showing up in rustdoc.

Ah, looks like this is a nearing-three-year-old bug with primitives: #25893

canndrew · 2018-03-15T06:01:45Z

It looks like the travis failure here had nothing to do with this PR.

@alexcrichton

Replace uninhabited error enums in std with never Luckily I only found two, and one of them isn't in beta yet, so can disappear completely 😎 Are there any others I forgot? (There are lots in things like liblibc and libstd/sys, but AFAIK those don't matter, nor do things like `btree::node::LeafOrInternal` or `str::pattern::RejectAndMatch`.) The unstable `convert::Infallible` is being handled by #49038 ⚠️ This change may be a 1.26-or-never one. cc #48950 (comment) r? @alexcrichton

SimonSapin · 2018-03-16T14:41:25Z

tidy error: /checkout/src/libcore/num/mod.rs:3598: trailing whitespace

canndrew · 2018-03-16T15:39:02Z

Oops, thanks for pointing that out.

SimonSapin · 2018-03-17T14:37:31Z

[01:27:14] ---- [rustdoc] rustdoc/synthetic_auto/no-redundancy.rs stdout ----
[01:27:14] 	
[01:27:14] error: htmldocck failed!
[01:27:14] status: exit code: 1
[01:27:14] command: "/usr/bin/python2.7" "/checkout/src/etc/htmldocck.py" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc/synthetic_auto/no-redundancy.stage2-x86_64-unknown-linux-gnu" "/checkout/src/test/rustdoc/synthetic_auto/no-redundancy.rs"
[01:27:14] stdout:
[01:27:14] ------------------------------------------
[01:27:14] 
[01:27:14] ------------------------------------------
[01:27:14] stderr:
[01:27:14] ------------------------------------------
[01:27:14] 22: @has check failed
[01:27:14] thread 'main' panicked at 'Some tests failed', tools/compiletest/src/main.rs:478:22
[01:27:14] 	`XPATH PATTERN` did not match
[01:27:14] 	// @has - '//*[@id="synthetic-implementations-list"]/*[@class="impl"]/*/code' "impl<T> Send for Outer<T> where T: Copy + Send"
[01:27:14] 
[01:27:14] Encountered 1 errors
[01:27:14] 
[01:27:14] ------------------------------------------
[01:27:14] 
[01:27:14] thread '[rustdoc] rustdoc/synthetic_auto/no-redundancy.rs' panicked at 'explicit panic', tools/compiletest/src/runtest.rs:2903:9
[01:27:14] 
[01:27:14] 
[01:27:14] failures:
[01:27:14]     [rustdoc] rustdoc/synthetic_auto/no-redundancy.rs

This looks like the same as #48265 (comment), you may need to swap the order of bounds in the expected rustdoc output in the comment in src/test/rustdoc/synthetic_auto/no-redundancy.rs.

Something like ./x.py test src/test/rustdoc --test-args no-redundancy should run just this test.

SimonSapin · 2018-03-17T23:04:08Z

I’ve filed #49123 for that rustdoc test failure.

SimonSapin · 2018-03-21T23:43:21Z

#49058 disabled that failing test.

@bors: r+

bors · 2018-03-21T23:43:22Z

📌 Commit 15bab45 has been approved by SimonSapin

…ver, r=SimonSapin replace `convert::Infallible` with `!`

Rollup of 23 pull requests - Successful merges: #48374, #48596, #48759, #48939, #49029, #49069, #49093, #49109, #49117, #49140, #49158, #49188, #49189, #49209, #49211, #49216, #49225, #49231, #49234, #49242, #49244, #49105, #49038 - Failed merges:

F001 · 2018-03-29T01:40:24Z

There are several empty enum types in std. For example:

impl FromStr for String {
  type Err = ParseError;
}

My question is, are they going to be replaced by ! type ?
The type pub enum ParseError {} has been stabilized. Is it a breaking change if we replace it by ! ?

SimonSapin · 2018-03-29T05:49:58Z

This is being discussed at #49039

replace convert::Infallible with !

4647156

rust-highfive assigned sfackler Mar 15, 2018

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 15, 2018

This was referenced Mar 15, 2018

Stabilise feature(never_type). Introduce feature(exhaustive_patterns) #47630

Merged

Tracking issue for TryFrom/TryInto traits #33417

Closed

scottmcm reviewed Mar 15, 2018

View reviewed changes

scottmcm mentioned this pull request Mar 15, 2018

Replace uninhabited error enums in std with never #49039

Closed

Add From<!> for TryFromIntError

15bab45

canndrew force-pushed the replace-infallible-with-never branch from edb2fdb to 15bab45 Compare March 16, 2018 15:38

SimonSapin mentioned this pull request Mar 18, 2018

Rustdoc: where bounds order in synthetic impls is not deterministic #49123

Closed

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 21, 2018

kennytm added a commit to kennytm/rust that referenced this pull request Mar 22, 2018

Rollup merge of rust-lang#49038 - canndrew:replace-infallible-with-ne…

2c6f911

…ver, r=SimonSapin replace `convert::Infallible` with `!`

kennytm mentioned this pull request Mar 22, 2018

Rollup of 23 pull requests #49264

Merged

alexcrichton merged commit 15bab45 into rust-lang:master Mar 22, 2018

vlad20012 mentioned this pull request Mar 29, 2018

ANN: add type mismatch quick fix using TryFrom intellij-rust/intellij-rust#2403

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

replace `convert::Infallible` with `!` #49038

replace `convert::Infallible` with `!` #49038

canndrew commented Mar 15, 2018

rust-highfive commented Mar 15, 2018

scottmcm left a comment

scottmcm Mar 15, 2018 •

edited

Loading

canndrew Mar 15, 2018 •

edited

Loading

scottmcm Mar 15, 2018

canndrew Mar 15, 2018

scottmcm Mar 15, 2018

canndrew commented Mar 15, 2018

SimonSapin commented Mar 16, 2018

canndrew commented Mar 16, 2018

SimonSapin commented Mar 17, 2018

SimonSapin commented Mar 17, 2018

SimonSapin commented Mar 21, 2018

bors commented Mar 21, 2018

F001 commented Mar 29, 2018 •

edited

Loading

SimonSapin commented Mar 29, 2018

replace convert::Infallible with ! #49038

replace convert::Infallible with ! #49038

Conversation

canndrew commented Mar 15, 2018

rust-highfive commented Mar 15, 2018

scottmcm left a comment

Choose a reason for hiding this comment

scottmcm Mar 15, 2018 • edited Loading

Choose a reason for hiding this comment

canndrew Mar 15, 2018 • edited Loading

Choose a reason for hiding this comment

scottmcm Mar 15, 2018

Choose a reason for hiding this comment

canndrew Mar 15, 2018

Choose a reason for hiding this comment

scottmcm Mar 15, 2018

Choose a reason for hiding this comment

canndrew commented Mar 15, 2018

SimonSapin commented Mar 16, 2018

canndrew commented Mar 16, 2018

SimonSapin commented Mar 17, 2018

SimonSapin commented Mar 17, 2018

SimonSapin commented Mar 21, 2018

bors commented Mar 21, 2018

F001 commented Mar 29, 2018 • edited Loading

SimonSapin commented Mar 29, 2018

replace `convert::Infallible` with `!` #49038

replace `convert::Infallible` with `!` #49038

scottmcm Mar 15, 2018 •

edited

Loading

canndrew Mar 15, 2018 •

edited

Loading

F001 commented Mar 29, 2018 •

edited

Loading