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Include output stream in panic!() documentation - #83254

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jfrimmel:panic_output-stream
Mar 20, 2021
Merged

Include output stream in panic!() documentation#83254
bors merged 4 commits into
rust-lang:masterfrom
jfrimmel:panic_output-stream

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@jfrimmel

@jfrimmeljfrimmel commented Mar 18, 2021•
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Fixes#83252.

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rust-highfive commented Mar 18, 2021

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r? @joshtriplett

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@rust-highfiverust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 18, 2021
@Dylan-DPC-zz

Dylan-DPC-zz commented Mar 18, 2021

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@bors r+ rollup

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bors commented Mar 18, 2021

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📌 Commit 55d9e0f has been approved by Dylan-DPC

@borsbors 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 18, 2021
@m-ou-se

m-ou-se commented Mar 18, 2021•
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The string built by this macro (using the [`format!`] syntax for building the actual message) is printed to `stderr`.

This is only what the default hook in std does, which can be overridden, or might not even exist (in no_std programs). The panic macro itself doesn't print anything to stderr; the concept of stderr or printing doesn't even exist in core.

I'm not objecting to documenting what happens by default with std, but we shouldn't claim that this behaviour is a property of the panic!() macro itself. Maybe something like "std's default panic hook will ..", with a link to std::panic::set_hook.

@bors r-

@borsbors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Mar 18, 2021
@m-ou-sem-ou-se added the T-libs-api [DEPRECATED; DO NOT USE] label Mar 18, 2021
@jfrimmel
Add more information about panicking
61e5d54
This includes the description of the default `std` behavior and mentions
the `panic::set_hook()` function.
@jfrimmel

jfrimmel commented Mar 18, 2021•
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I've incorporated your feedback @m-ou-se. I hope this is both helpful to a reader and concise while still being technically correct. Despite this file being in core, I'd like to mention the std-behavior prominently, as most of the readers come from reading the std docs.

m-ou-se
m-ou-se reviewed Mar 18, 2021
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Thanks. Looking better now. I have a few more comments:

Comment threadlibrary/core/src/macros/panic.md Outdated
Comment threadlibrary/core/src/macros/panic.md Outdated
@m-ou-sem-ou-se assigned m-ou-se and unassigned Dylan-DPC-zzMar 18, 2021
@Dylan-DPC-zz

Dylan-DPC-zz commented Mar 18, 2021

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@bors r-

r? @m-ou-se

@jfrimmel

jfrimmel commented Mar 18, 2021

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Didn't intend to make this much noise in such a small change, apologies.

@m-ou-se

m-ou-se commented Mar 18, 2021

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Didn't intend to make this much noise in such a small change, apologies.

Oh I'm very happy you're doing this! Clearly we were missing documentation here. Looks like we didn't even explain anywhere what happens with panic!() in std. So this is an important change you're making!

@m-ou-se

m-ou-se commented Mar 18, 2021

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This looks great now. Thanks!

@bors r+ rollup

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📌 Commit d5e45b5 has been approved by m-ou-se

@borsbors 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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 18, 2021
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A few typos; otherwise LGTM, and I'm glad to see this documented.

Comment threadlibrary/core/src/macros/panic.md Outdated
Comment threadlibrary/core/src/macros/panic.md Outdated
Comment threadlibrary/core/src/macros/panic.md Outdated
@jfrimmel@joshtriplett
Apply suggestions from code review
19bd066
Co-authored-by: Josh Triplett <josh@joshtriplett.org>
@joshtriplett

joshtriplett commented Mar 18, 2021

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Thanks for the quick update! 👍

@m-ou-se

m-ou-se commented Mar 19, 2021

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@bors r=m-ou-se,joshtriplett

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bors commented Mar 19, 2021

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📌 Commit 19bd066 has been approved by m-ou-se,joshtriplett

@Dylan-DPC-zzDylan-DPC-zz mentioned this pull request Mar 19, 2021
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bors added a commit to rust-lang-ci/rust that referenced this pull request Mar 19, 2021
@bors
Auto merge ofrust-lang#83308- Dylan-DPC:rollup-p2j6sy8, r=Dylan-DPC
6bfbf0c
Rollup of 8 pull requests
Successful merges:
- rust-lang#79986 (Only build help popup when it's really needed)
- rust-lang#82570 (Add `as_str` method for split whitespace str iterators)
- rust-lang#83244 (Fix overflowing length in Vec<ZST> to VecDeque)
- rust-lang#83254 (Include output stream in `panic!()` documentation)
- rust-lang#83269 (Revert the second deprecation of collections::Bound)
- rust-lang#83277 (Mark early otherwise optimization unsound)
- rust-lang#83285 (Update LLVM to bring in SIMD updates for WebAssembly)
- rust-lang#83297 (Do not ICE on ty::Error as an error must already have been reported)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
@bors
bors merged commit 2cc5d72 into rust-lang:masterMar 20, 2021
@rustbotrustbot added this to the 1.52.0 milestone Mar 20, 2021
@jfrimmel
jfrimmel deleted the panic_output-stream branch October 14, 2021 14:03
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Successfully merging this pull request may close these issues.

std::panic macro documentation does not specify where the string is printed to (stdout or stderr)

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