Revert "dates: refresh type system & traits date annotations to Aug/2025"

Author: tshepang

src/doc/rustc-dev-guide/src/borrow_check/region_inference/member_constraints.md

@@ -92,7 +92,7 @@ member constraints come in.
 ## Choices are always lifetime parameters
 
 At present, the "choice" regions from a member constraint are always lifetime
-parameters from the current function. As of <!-- date-check --> August 2025,
+parameters from the current function. As of <!-- date-check --> October 2021,
 this falls out from the placement of impl Trait, though in the future it may not
 be the case. We take some advantage of this fact, as it simplifies the current
 code. In particular, we don't have to consider a case like `'0 member of ['1,

src/doc/rustc-dev-guide/src/opaque-types-type-alias-impl-trait.md

@@ -15,7 +15,7 @@ it implements `Bar`. Therefore, any of `Bar`'s interface can be used on a `Foo`,
 but nothing else (regardless of whether it implements any other traits).
 
 Since there needs to be a concrete background type,
-you can (as of <!-- date-check --> August 2025) express that type
+you can (as of <!-- date-check --> January 2021) express that type
 by using the opaque type in a "defining use site".
 
 ```rust,ignore

src/doc/rustc-dev-guide/src/stability.md

@@ -30,7 +30,7 @@ unstable modules or vice versa.
 
 Previously, due to a [rustc bug], stable items inside unstable modules were
 available to stable code in that location.
-As of <!-- date-check --> August 2025, items with [accidentally stabilized
+As of <!-- date-check --> September 2024, items with [accidentally stabilized
 paths] are marked with the `#[rustc_allowed_through_unstable_modules]` attribute
 to prevent code dependent on those paths from breaking. Do *not* add this attribute
 to any more items unless that is needed to avoid breaking changes.

src/doc/rustc-dev-guide/src/thir.md

@@ -2,7 +2,7 @@
 
 The THIR ("Typed High-Level Intermediate Representation"), previously called HAIR for
 "High-Level Abstract IR", is another IR used by rustc that is generated after
-[type checking]. It is (as of <!-- date-check --> August 2025) used for
+[type checking]. It is (as of <!-- date-check --> January 2024) used for
 [MIR construction], [exhaustiveness checking], and [unsafety checking].
 
 [type checking]: ./type-checking.md
@@ -52,7 +52,7 @@ fn main() {
 }
 ```
 
-Here is how that gets represented in THIR (as of <!-- date-check --> August 2025):
+Here is how that gets represented in THIR (as of <!-- date-check --> Aug 2022):
 
 ```rust,no_run
 Thir {

src/doc/rustc-dev-guide/src/traits/chalk.md

@@ -1,7 +1,7 @@
 # Chalk-based trait solving
 
 [Chalk][chalk] is an experimental trait solver for Rust that is
-(as of <!-- date-check --> August 2025) under development by the [Types team].
+(as of <!-- date-check --> May 2022) under development by the [Types team].
 Its goal is to enable a lot of trait system features and bug fixes
 that are hard to implement (e.g. GATs or specialization). If you would like to
 help in hacking on the new solver, drop by on the rust-lang Zulip in the [`#t-types`]

src/doc/rustc-dev-guide/src/traits/resolution.md

@@ -120,7 +120,7 @@ the obligation contains unbound inference variables.
 
 The subroutines that decide whether a particular impl/where-clause/etc applies
 to a particular obligation are collectively referred to as the process of
-_matching_. For `impl` candidates <!-- date-check: Aug 2025 -->,
+_matching_. For `impl` candidates <!-- date-check: Oct 2022 -->,
 this amounts to unifying the impl header (the `Self` type and the trait arguments)
 while ignoring  nested obligations. If matching succeeds then we add it
 to a set of candidates. There are other rules when assembling candidates for

src/doc/rustc-dev-guide/src/ty-fold.md

@@ -1,4 +1,4 @@
-<!-- date-check: Aug 2025 -->
+<!-- date-check: may 2024 -->
 # `TypeFoldable` and `TypeFolder`
 
 In [a previous chapter], we discussed instantiating binders.

src/doc/rustc-dev-guide/src/type-inference.md

@@ -66,7 +66,7 @@ inference works, or perhaps this blog post on
 [Unification in the Chalk project]: http://smallcultfollowing.com/babysteps/blog/2017/03/25/unification-in-chalk-part-1/
 
 All told, the inference context stores five kinds of inference variables
-(as of <!-- date-check --> August 2025):
+(as of <!-- date-check --> March 2023):
 
 - Type variables, which come in three varieties:
   - General type variables (the most common). These can be unified with any