New lint `if_then_panic` by Labelray · Pull Request #7669 · rust-lang/rust-clippy

Labelray · 2021-09-14T08:33:55Z

changelog: add the new lint [if_then_panic]
fix #7645

rust-highfive · 2021-09-14T08:33:58Z

(rust-highfive has picked a reviewer for you, use r? to override)

camsteffen · 2021-09-14T13:34:11Z

Use cx.sess().source_map().is_multiline(span) to make sure the condition fits on on line as noted in the issue. Add a negative test for this.

I think providing a code suggestion is important for this lint. The fix may not be intuitive and people may not be aware that assert! accepts a message and formatting args. We probably need PanicMacroExpn similar to FormatExpn.

camsteffen · 2021-09-18T15:30:09Z

I'll leave it to @giraffate do to a full review. But note I still don't see the multi-line check. @Labelray don't hesitate to ask if something doesn't make sense!

Labelray · 2021-09-18T15:37:16Z

I'll leave it to @giraffate do to a full review. But note I still don't see the multi-line check. @Labelray don't hesitate to ask if something doesn't make sense!

@camsteffen I didn't check the number of lines but I checked the number of statements. I think it is better.

camsteffen · 2021-09-18T15:45:09Z

A long condition can be a single statement.

if some_function(foo, bar, baz) == another_function(hi, whats, up)
    && some_function(a, b, c) == another_function(a, b, c) {
    panic!();
}

giraffate

I made a comment but overall looks good, thanks!

giraffate · 2021-09-24T00:18:17Z

+error: only a `panic!` in `if`-then statement
+  --> $DIR/fallible_impl_from.rs:28:9
+   |
+LL | /         if i != 42 {
+LL | |             panic!();
+LL | |         }
+   | |_________^ help: try: `assert!(!i != 42, "explicit panic");`
+   |
+   = note: `-D clippy::if-then-panic` implied by `-D warnings`
+


Can you add #![allow(clippy::if_then_panic)] and remove these warnings in this test file? It looks a little confusing.

If this suggestion even valid?

!i != 42 is (!i) != 42 which is not what is intended to be suggested here. It should be !(i != 42).

https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=a84683ba815f737b90acb285876d2365

Though, already reported: #7731

giraffate

Can the conflict be resolved?

giraffate · 2021-09-24T13:55:13Z

We follow a no merge-commit policy. Can you do a rebase, not a merge?

giraffate · 2021-09-24T14:35:53Z

@bors r+

Thanks!

bors · 2021-09-24T14:35:55Z

📌 Commit 543b638 has been approved by giraffate

bors · 2021-09-24T14:43:55Z

⌛ Testing commit 543b638 with merge fb61d04...

bors · 2021-09-24T14:56:28Z

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: giraffate
Pushing fb61d04 to master...

Most of the changes are for the new if-then-panic lint added in rust-lang/rust-clippy#7669. Error messages look like: error: only a `panic!` in `if`-then statement --> zenith_utils/src/lsn.rs:195:9 | 195 | / if prev.checked_add(val).is_none() { 196 | | panic!("AtomicLsn overflow"); 197 | | } | |_________^ help: try: `assert!(!prev.checked_add(val).is_none(), "AtomicLsn overflow");` | = note: `-D clippy::if-then-panic` implied by `-D warnings` = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#if_then_panic

Most of the changes are for the new if-then-panic lint added in rust-lang/rust-clippy#7669.

Jasperav · 2021-10-19T18:15:14Z

@camsteffen @giraffate This issue causes regression: panic! can be catch with std::panic::catch_unwind, but assert! not. This broke my code and can break other people's code as well if panic! is unconditionally replaced with assert! (when using the catch_unwind since there won't be a catch but the whole program is terminated), so it should not be suggested as a 'fix'.

I would suggest reverting this lint or don't make it active by default (not sure if this is possible)

Jasperav · 2021-10-19T19:27:04Z

This lint also transformed this code:

let x = 10;
if x == 0 {
    panic!("fail");
}

to

let x = 10;
assert!(!x == 0, "fail");

which... is weird. Why negate an integer? This also breaks my code since this assertion is now triggered, while the initial code wasn't being triggered.

camsteffen · 2021-10-19T21:41:15Z

Hi @Jasperav, thanks for the feedback.

This issue causes regression: panic! can be catch with std::panic::catch_unwind, but assert! not.

I don't think this is true, unless I misunderstood. See playground.

I would suggest reverting this lint or don't make it active by default

The lint is being moved to pedantic (off by default) in #7810.

which... is weird. Why negate an integer?

This should be fixed from #7741.

Jasperav · 2021-10-20T06:55:39Z

Edit: apparently, it can indeed catch assertions. Not sure what went wrong with my code.

Most of the changes are for the new if-then-panic lint added in rust-lang/rust-clippy#7669.

rust-highfive assigned giraffate Sep 14, 2021

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties label Sep 14, 2021

Labelray force-pushed the if_then_panic branch 4 times, most recently from bf3194e to 5761bb7 Compare September 14, 2021 09:15

Labelray force-pushed the if_then_panic branch from 5761bb7 to 0e5ccd7 Compare September 17, 2021 02:30

camsteffen reviewed Sep 17, 2021

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Comment thread clippy_utils/src/higher.rs Outdated

Labelray force-pushed the if_then_panic branch from 0e5ccd7 to 9e85dc8 Compare September 18, 2021 15:12

Labelray force-pushed the if_then_panic branch from 9e85dc8 to 73040c3 Compare September 19, 2021 04:33

giraffate reviewed Sep 21, 2021

View reviewed changes

Comment thread clippy_lints/src/if_then_panic.rs

Comment thread clippy_lints/src/if_then_panic.rs Outdated

Labelray force-pushed the if_then_panic branch 3 times, most recently from 0d3c4f9 to 44ad749 Compare September 22, 2021 00:45

giraffate reviewed Sep 24, 2021

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Labelray force-pushed the if_then_panic branch from 44ad749 to 5f750a8 Compare September 24, 2021 11:13

giraffate approved these changes Sep 24, 2021

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Labelray force-pushed the if_then_panic branch from 4807d0d to 5f750a8 Compare September 24, 2021 13:47

Labelray force-pushed the if_then_panic branch from 91d7588 to 1d8d337 Compare September 24, 2021 14:10

Add new lint if_then_panic

543b638

Labelray force-pushed the if_then_panic branch from 1d8d337 to 543b638 Compare September 24, 2021 14:14

bors merged commit fb61d04 into rust-lang:master Sep 24, 2021

camsteffen mentioned this pull request Sep 24, 2021

Manual assert_eq! (enhance if_then_panic) #7716

Open

Labelray deleted the if_then_panic branch September 25, 2021 03:08

sharnoff mentioned this pull request Sep 30, 2021

More nightly clippy fixes (2021-09-29) neondatabase/neon#691

Merged

sharnoff added a commit to neondatabase/neon that referenced this pull request Oct 1, 2021

Fix clippy errors on nightly (2021-09-29) (#691)

84f7dcd

Most of the changes are for the new if-then-panic lint added in rust-lang/rust-clippy#7669.

zeekay pushed a commit to hanzosql/neon that referenced this pull request Sep 10, 2026

Fix clippy errors on nightly (2021-09-29) (neondatabase#691)

cce654c

Most of the changes are for the new if-then-panic lint added in rust-lang/rust-clippy#7669.

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Labelray commented Sep 14, 2021 •

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