1757069 - Deprecated `procedural-masquerade` crate used by cascade_bloom_filter will soon become hard compiler error

Status: RESOLVED INVALID

(Toolkit :: Blocklist Implementation, defect, P2)

Description

[Chris Martin [:cmartin]]

The following appears when I compile Firefox on my Windows 10 machine:

0:20.92 warning: using `procedural-masquerade` crate
 0:20.92   --> toolkit\components\cascade_bloom_filter\src\lib.rs:24:1
 0:20.92    |
 0:20.92 24 | / rental! {
 0:20.92 25 | |     mod rentals {
 0:20.92 26 | |         use super::Cascade;
 0:20.92 27 | |
 0:20.92 ...  |
 0:20.92 33 | |     }
 0:20.92 34 | | }
 0:20.92    | |_^
 0:20.92    |
 0:20.92    = note: `#[warn(proc_macro_back_compat)]` on by default
 0:20.92    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 0:20.92    = note: for more information, see issue #83125 <https://github.com/rust-lang/rust/issues/83125>
 0:20.92    = note: The `procedural-masquerade` crate has been unnecessary since Rust 1.30.0. Versions of this crate below 0.1.7 will eventually stop compiling.
 0:20.92    = note: this warning originates in the macro `rental` (in Nightly builds, run with -Z macro-backtrace for more info)

Comment 1

[:Gijs (he/him)]

Rob, looks like you added this code and I have no idea what procedural-masquerade is and/or how to fix this - can you take a look?

Comment 2

[Emilio Cobos Álvarez [:emilio]]

I thought this was a false positive but icbw. If Rob doesnt have the time to dig feel free to redirect the ni? to me and I'll get to it.

Comment 3

[Rob Wu [:robwu]]

I don't readily know what to do here, so I'll redirect the needinfo to you. Thanks!

Comment 4

[Emilio Cobos Álvarez [:emilio]]

Ok, so I think this is invalid. The warning triggers incorrectly for rental 0.5.6 which is what we use. https://github.com/rust-lang/rust/pull/94063 will fix the warning on the Rust side, though Rental is unmaintained and should go away. Bug 1615974 should remove the rental crate, so that's the right fix.