Allow while let chains on all editions

compiler/rustc_parse/src/parser/expr.rs

@@ -3020,7 +3020,7 @@ impl<'a> Parser<'a> {
 
     /// Parses a `while` or `while let` expression (`while` token already eaten).
     fn parse_expr_while(&mut self, opt_label: Option<Label>, lo: Span) -> PResult<'a, P<Expr>> {
-        let policy = LetChainsPolicy::EditionDependent { current_edition: lo.edition() };
+        let policy = LetChainsPolicy::AlwaysAllowed;
         let cond = self.parse_expr_cond(policy).map_err(|mut err| {
             err.span_label(lo, "while parsing the condition of this `while` expression");
             err

tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions.rs

@@ -76,8 +76,6 @@ fn _while() {
     //~^ ERROR expected expression, found `let` statement
     //~| ERROR expected expression, found `let` statement
     //~| ERROR expected expression, found `let` statement
-    //[no_feature]~| ERROR `let` expressions in this position are unstable
-    //[no_feature]~| ERROR `let` expressions in this position are unstable
 }
 
 #[cfg(not(nothing))]

tests/ui/rfcs/rfc-2497-if-let-chains/feature-gate.rs

@@ -30,13 +30,10 @@ fn _while() {
     while let 0 = 1 {} // Stable!
 
     while true && let 0 = 1 {}
-    //~^ ERROR `let` expressions in this position are unstable [E0658]
 
     while let 0 = 1 && true {}
-    //~^ ERROR `let` expressions in this position are unstable [E0658]
 
     while let Range { start: _, end: _ } = (true..true) && false {}
-    //~^ ERROR `let` expressions in this position are unstable [E0658]
 }
 
 fn _macros() {

tests/ui/rfcs/rfc-2497-if-let-chains/feature-gate.stderr

@@ -1,21 +1,21 @@
 error: expected expression, found `let` statement
-  --> $DIR/feature-gate.rs:54:20
+  --> $DIR/feature-gate.rs:51:20
    |
 LL |     #[cfg(false)] (let 0 = 1);
    |                    ^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: expected expression, found `let` statement
-  --> $DIR/feature-gate.rs:45:17
+  --> $DIR/feature-gate.rs:42:17
    |
 LL |     noop_expr!((let 0 = 1));
    |                 ^^^
    |
    = note: only supported directly in conditions of `if` and `while` expressions
 
 error: no rules expected keyword `let`
-  --> $DIR/feature-gate.rs:56:15
+  --> $DIR/feature-gate.rs:53:15
    |
 LL |     macro_rules! use_expr {
    |     --------------------- when calling this macro
@@ -24,7 +24,7 @@ LL |     use_expr!(let 0 = 1);
    |               ^^^ no rules expected this token in macro call
    |
 note: while trying to match meta-variable `$e:expr`
-  --> $DIR/feature-gate.rs:49:10
+  --> $DIR/feature-gate.rs:46:10
    |
 LL |         ($e:expr) => {
    |          ^^^^^^^
@@ -79,36 +79,6 @@ LL |     if let 1 = 1 && let true = { true } && false {
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:32:19
-   |
-LL |     while true && let 0 = 1 {}
-   |                   ^^^^^^^^^
-   |
-   = note: see issue #53667 <https://github.com/rust-lang/rust/issues/53667> for more information
-   = help: add `#![feature(let_chains)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:35:11
-   |
-LL |     while let 0 = 1 && true {}
-   |           ^^^^^^^^^
-   |
-   = note: see issue #53667 <https://github.com/rust-lang/rust/issues/53667> for more information
-   = help: add `#![feature(let_chains)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error[E0658]: `let` expressions in this position are unstable
-  --> $DIR/feature-gate.rs:38:11
-   |
-LL |     while let Range { start: _, end: _ } = (true..true) && false {}
-   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #53667 <https://github.com/rust-lang/rust/issues/53667> for more information
-   = help: add `#![feature(let_chains)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error: aborting due to 11 previous errors
+error: aborting due to 8 previous errors
 
 For more information about this error, try `rustc --explain E0658`.