remove the explicit error for old rental versions

[cyrgani]

This was converted to a hard error 20 months ago (in #125596). This seems like enough time for anyone still using it to notice, so remove the note entirely now.
In comparison, the explicit note for the more impactful time breakage was already removed after 6 months (#129343).

Closes #73933.
Closes #83125.

r? @petrochenkov

[petrochenkov]

Could you remove the tests in a separate second commit?
I'm interested how the output looks after the change.
@rustbot author

[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[cyrgani]

The tests don't have any interesting output to show after this change since they are essentially just checking for a type named ProceduralMasqueradeDummyType in a crate named rental and not for the actual failure pattern in rental. They just compile again.

[cyrgani]

The output from compiling the real rental=0.5.5 is:

error: proc-macro derive panicked
   --> /home/gh-cyrgani/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/rental-0.5.5/src/lib.rs:93:12
    |
 93 |         #[derive(__rental_traits)]
    |                  ^^^^^^^^^^^^^^^
...
117 |     define_rental_traits!(32);
    |     ------------------------- in this macro invocation
    |
    = help: message: expected suffix ").0," not found in "#[allow(unused)] enum ProceduralMasqueradeDummyType\n{ Input = (0, stringify! (32)).0 }"
    = note: this error originates in the macro `define_rental_traits` (in Nightly builds, run with -Z macro-backtrace for more info)

error: proc-macro derive panicked
   --> /home/gh-cyrgani/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/rental-0.5.5/src/lib.rs:257:13
    |
257 |               #[derive(__rental_structs_and_impls)]
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^
...
285 | / rental! {
286 | |     /// Example types that demonstrate the API generated by the rental macro.
287 | |     pub mod examples {
288 | |         use std::sync;
...   |
346 | | }
    | |_- in this macro invocation
    |
    = help: message: expected suffix ").0," not found in "#[allow(unused)] enum ProceduralMasqueradeDummyType\n{\n    Input =\n    (0, stringify!\n    (use std::sync;\n    #[doc =\n    r\" The simplest shared rental. The head is a boxed integer, and the suffix is a ref to that integer. This struct demonstrates the basic API that all shared rental structs have. See [`SimpleMut`](struct.SimpleMut.html) for the mutable analog.\"]\n    #[rental] pub struct SimpleRef { head: Box<i32>, iref: &'head i32, }\n    #[doc =\n    r\" The simplest mutable rental. Mutable rentals have a slightly different API; compare this struct to [`SimpleRef`](struct.SimpleRef.html) for the clearest picture of how they differ.\"]\n    #[rental_mut] pub struct SimpleMut\n    { head: Box<i32>, iref: &'head mut i32, }\n    #[doc =\n    r\" Identical to [`SimpleRef`](struct.SimpleRef.html), but with the `debug` flag enabled. This will provide a `Debug` impl for the struct as long as all of the fields are `Debug`.\"]\n    #[rental(debug)] pub struct SimpleRefDebug\n    { head: Box<i32>, iref: &'head i32, }\n    #[doc =\n    r\" Similar to [`SimpleRef`](struct.SimpleRef.html), but with the `clone` flag enabled. This will provide a `Clone` impl for the struct as long as the prefix fields are `CloneStableDeref` and the suffix is `Clone` . Notice that the head is an `Arc`, since a clone of an `Arc` will deref to the same object as the original.\"]\n    #[rental(clone)] pub struct SimpleRefClone\n    { head: sync::Arc<i32>, iref: &'head i32, }\n    #[doc =\n    r\" Identical to [`SimpleRef`](struct.SimpleRef.html), but with the `deref_suffix` flag enabled. This will provide a `Deref` impl for the struct, which will in turn deref the suffix. Notice that this flag also removes the `self` param from all methods, replacing it with an explicit param. This prevents any rental methods from blocking deref.\"]\n    #[rental(deref_suffix)] pub struct SimpleRefDeref\n    { head: Box<i32>, iref: &'head i32, }\n    #[doc =\n    r\" Identical to [`SimpleMut`](struct.SimpleMut.html), but with the `deref_mut_suffix` flag enabled. This will provide a `DerefMut` impl for the struct, which will in turn deref the suffix.Notice that this flag also removes the `self` param from all methods, replacing it with an explicit param. This prevents any rental methods from blocking deref.\"]\n    #[rental_mut(deref_mut_suffix)] pub struct SimpleMutDeref\n    { head: Box<i32>, iref: &'head mut i32, }\n    #[doc =\n    r\" Identical to [`SimpleRef`](struct.SimpleRef.html), but with the `covariant` flag enabled. For rental structs where the field types have covariant lifetimes, this will allow you to directly borrow the fields, as they can be safely reborrowed to a shorter lifetime. See the [`all`](struct.SimpleRefCovariant.html#method.all) and [`suffix`](struct.SimpleRefCovariant.html#method.suffix) methods.\"]\n    #[rental(covariant)] pub struct SimpleRefCovariant\n    { head: Box<i32>, iref: &'head i32, }\n    #[doc =\n    r\" Identical to [`SimpleRef`](struct.SimpleRef.html), but with the `map_suffix` flag enabled. This will allow the type of the suffix to be changed by mapping it to another instantiation of the same struct with the different type param. See the [`map`](struct.SimpleRefMap.html#method.map), [`try_map`](struct.SimpleRefMap.html#method.try_map), and [`try_map_or_drop`](struct.SimpleRefMap.html#method.try_map_or_drop) methods.\"]\n    #[rental(map_suffix = \"T\")] pub struct SimpleRefMap<T: 'static>\n    { head: Box<i32>, iref: &'head T, })).0\n}"
    = note: this error originates in the macro `rental` (in Nightly builds, run with -Z macro-backtrace for more info)

error: proc-macro derive panicked
   --> /home/gh-cyrgani/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/rental-0.5.5/src/lib.rs:257:13
    |
257 |               #[derive(__rental_structs_and_impls)]
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^
...
350 | / rental! {
351 | |     /// Premade types for the most common use cases.
352 | |     pub mod common {
353 | |         use std::ops::DerefMut;
...   |
485 | | }
    | |_- in this macro invocation
    |
    = help: message: expected suffix ").0," not found in "#[allow(unused)] enum ProceduralMasqueradeDummyType\n{\n    Input =\n    (0, stringify!\n    (use std::ops::DerefMut; use stable_deref_trait::StableDeref; use\n    std::cell; use std::sync;\n    #[doc = r\" Stores an owner and a shared reference in the same struct.\"]\n    #[doc = r\"\"] #[doc = r\" ```rust\"] #[doc = r\" # extern crate rental;\"]\n    #[doc = r\" # use rental::common::RentRef;\"] #[doc = r\" # fn main() {\"]\n    #[doc = r\" let r = RentRef::new(Box::new(5), |i| &*i);\"]\n    #[doc = r\" assert_eq!(*r, RentRef::rent(&r, |iref| **iref));\"]\n    #[doc = r\" # }\"] #[doc = r\" ```\"]\n    #[rental(debug, clone, deref_suffix, covariant, map_suffix = \"T\")] pub\n    struct RentRef<H: 'static + StableDeref, T: 'static>\n    { head: H, suffix: &'head T, }\n    #[doc = r\" Stores an owner and a mutable reference in the same struct.\"]\n    #[doc = r\"\"] #[doc = r\" ```rust\"] #[doc = r\" # extern crate rental;\"]\n    #[doc = r\" # use rental::common::RentMut;\"] #[doc = r\" # fn main() {\"]\n    #[doc = r\" let mut r = RentMut::new(Box::new(5), |i| &mut *i);\"]\n    #[doc = r\" *r = 12;\"]\n    #[doc = r\" assert_eq!(12, RentMut::rent(&mut r, |iref| **iref));\"]\n    #[doc = r\" # }\"] #[doc = r\" ```\"]\n    #[rental_mut(debug, deref_mut_suffix, covariant, map_suffix = \"T\")] pub\n    struct RentMut<H: 'static + StableDeref + DerefMut, T: 'static>\n    { head: H, suffix: &'head mut T, }\n    #[doc = r\" Stores a `RefCell` and a `Ref` in the same struct.\"]\n    #[doc = r\"\"] #[doc = r\" ```rust\"] #[doc = r\" # extern crate rental;\"]\n    #[doc = r\" # use rental::common::RentRefCell;\"] #[doc = r\" # fn main() {\"]\n    #[doc = r\" use std::cell;\"] #[doc = r\"\"]\n    #[doc =\n    r\" let r = RentRefCell::new(Box::new(cell::RefCell::new(5)), |c| c.borrow());\"]\n    #[doc = r\" assert_eq!(*r, RentRefCell::rent(&r, |c| **c));\"]\n    #[doc = r\" # }\"] #[doc = r\" ```\"]\n    #[rental(debug, clone, deref_suffix, covariant, map_suffix = \"T\")] pub\n    struct RentRefCell<H: 'static + StableDeref, T: 'static>\n    { head: H, suffix: cell::Ref<'head, T>, }\n    #[doc = r\" Stores a `RefCell` and a `RefMut` in the same struct.\"]\n    #[doc = r\"\"] #[doc = r\" ```rust\"] #[doc = r\" # extern crate rental;\"]\n    #[doc = r\" # use rental::common::RentRefCellMut;\"]\n    #[doc = r\" # fn main() {\"] #[doc = r\" use std::cell;\"] #[doc = r\"\"]\n    #[doc =\n    r\" let mut r = RentRefCellMut::new(Box::new(cell::RefCell::new(5)), |c| c.borrow_mut());\"]\n    #[doc = r\" *r = 12;\"]\n    #[doc = r\" assert_eq!(12, RentRefCellMut::rent(&r, |c| **c));\"]\n    #[doc = r\" # }\"] #[doc = r\" ```\"]\n    #[rental_mut(debug, deref_mut_suffix, covariant, map_suffix = \"T\")] pub\n    struct RentRefCellMut<H: 'static + StableDeref + DerefMut, T: 'static>\n    { head: H, suffix: cell::RefMut<'head, T>, }\n    #[doc = r\" Stores a `Mutex` and a `MutexGuard` in the same struct.\"]\n    #[doc = r\"\"] #[doc = r\" ```rust\"] #[doc = r\" # extern crate rental;\"]\n    #[doc = r\" # use rental::common::RentMutex;\"] #[doc = r\" # fn main() {\"]\n    #[doc = r\" use std::sync;\"] #[doc = r\"\"]\n    #[doc =\n    r\" let mut r = RentMutex::new(Box::new(sync::Mutex::new(5)), |c| c.lock().unwrap());\"]\n    #[doc = r\" *r = 12;\"]\n    #[doc = r\" assert_eq!(12, RentMutex::rent(&r, |c| **c));\"]\n    #[doc = r\" # }\"] #[doc = r\" ```\"]\n    #[rental(debug, clone, deref_mut_suffix, covariant, map_suffix = \"T\")] pub\n    struct RentMutex<H: 'static + StableDeref + DerefMut, T: 'static>\n    { head: H, suffix: sync::MutexGuard<'head, T>, }\n    #[doc =\n    r\" Stores an `RwLock` and an `RwLockReadGuard` in the same struct.\"]\n    #[doc = r\"\"] #[doc = r\" ```rust\"] #[doc = r\" # extern crate rental;\"]\n    #[doc = r\" # use rental::common::RentRwLock;\"] #[doc = r\" # fn main() {\"]\n    #[doc = r\" use std::sync;\"] #[doc = r\"\"]\n    #[doc =\n    r\" let r = RentRwLock::new(Box::new(sync::RwLock::new(5)), |c| c.read().unwrap());\"]\n    #[doc = r\" assert_eq!(*r, RentRwLock::rent(&r, |c| **c));\"]\n    #[doc = r\" # }\"] #[doc = r\" ```\"]\n    #[rental(debug, clone, deref_suffix, covariant, map_suffix = \"T\")] pub\n    struct RentRwLock<H: 'static + StableDeref, T: 'static>\n    { head: H, suffix: sync::RwLockReadGuard<'head, T>, }\n    #[doc =\n    r\" Stores an `RwLock` and an `RwLockWriteGuard` in the same struct.\"]\n    #[doc = r\"\"] #[doc = r\" ```rust\"] #[doc = r\" # extern crate rental;\"]\n    #[doc = r\" # use rental::common::RentRwLockMut;\"]\n    #[doc = r\" # fn main() {\"] #[doc = r\" use std::sync;\"] #[doc = r\"\"]\n    #[doc =\n    r\" let mut r = RentRwLockMut::new(Box::new(sync::RwLock::new(5)), |c| c.write().unwrap());\"]\n    #[doc = r\" *r = 12;\"]\n    #[doc = r\" assert_eq!(12, RentRwLockMut::rent(&r, |c| **c));\"]\n    #[doc = r\" # }\"] #[doc = r\" ```\"]\n    #[rental(debug, clone, deref_mut_suffix, covariant, map_suffix = \"T\")] pub\n    struct RentRwLockMut<H: 'static + StableDeref, T: 'static>\n    { head: H, suffix: sync::RwLockWriteGuard<'head, T>, })).0\n}"
    = note: this error originates in the macro `rental` (in Nightly builds, run with -Z macro-backtrace for more info)

error: could not compile `rental` (lib) due to 3 previous errors

[petrochenkov]

@bors r+

[rust-bors]

📌 Commit 195b849 has been approved by petrochenkov

It is now in the queue for this repository.