panic_str only exists for the migration to 2021 panic macros

[RalfJung]

The only caller is expect_failed, which is already a cold inline(never) function, so inlining into that function should be fine. (And indeed panic_str was #[inline] anyway.)

The existence of panic_str risks someone calling it when they should call panic instead, and I can't see a reason why this footgun should exist.

I also extended the comment in panic to explain why it needs a 'static string -- I know I've wondered about this in the past and it took me quite a while to understand.

[rustbot]

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[RalfJung]

r? @m-ou-se

[m-ou-se]

panic_str is also used here:

rust/library/core/src/panic.rs

Lines 30 to 33 in 60b5ca6

	// Use `panic_str` instead of `panic_display::<&str>` for non_fmt_panic lint.
	($msg:expr $(,)?) => ({
	$crate::panicking::panic_str($msg);
	}),

(See also the diagram in #116005)

[RalfJung]

Ah, "find references" led me astray... I originally just wanted to add some comments, I will probably turn the PR into that then. (Assuming that lint can't easily access type information.)

[RalfJung]

It seems like that lint does have type information available via cx.typeck_results().expr_ty. So instead of checking for panic_str it could check for panic_display with an &&str argument -- or would that not give the right results?

[bors]

☔ The latest upstream changes (presumably #123065) made this pull request unmergeable. Please resolve the merge conflicts.

[RalfJung]

It seems like that lint does have type information available via cx.typeck_results().expr_ty. So instead of checking for panic_str it could check for panic_display with an &&str argument -- or would that not give the right results?

I guess that would not be right since the lint should kick in for println!(mystrvar) but not println!("{}", mystrvar).

[RalfJung]

@rustbot ready

[RalfJung]

@m-ou-se I have updated the PR based on your comment. Do you want to take another look or should I try to find a different reviewer?

[m-ou-se]

Lgtm! r=me when ready.

[RalfJung]

This is ready, I just rebased to fix a typo in the commit message. :)

@bors r=m-ou-se rollup

[bors]

📌 Commit 132921e has been approved by m-ou-se

It is now in the queue for this repository.