Rollup merge of #57175 - oli-obk:const_let_stabilization, r=nikomatsakis

Stabilize `let` bindings and destructuring in constants and const fn

r? @Centril

This PR stabilizes the following features in constants and `const` functions:

* irrefutable destructuring patterns (e.g. `const fn foo((x, y): (u8, u8)) { ... }`)
* `let` bindings (e.g. `let x = 1;`)
* mutable `let` bindings (e.g. `let mut x = 1;`)
* assignment (e.g. `x = y`) and assignment operator (e.g. `x += y`) expressions, even where the assignment target is a projection (e.g. a struct field or index operation like `x[3] = 42`)
* expression statements (e.g. `3;`)

This PR does explicitly *not* stabilize:

* mutable references (i.e. `&mut T`)
* dereferencing mutable references
* refutable patterns (e.g. `Some(x)`)
* operations on `UnsafeCell` types (as that would need raw pointers and mutable references and such, not because it is explicitly forbidden. We can't explicitly forbid it as such values are OK as long as they aren't mutated.)
* We are not stabilizing `let` bindings in constants that use `&&` and `||` short circuiting operations. These are treated as `&` and `|` inside `const` and `static` items right now. If we stopped treating them as `&` and `|` after stabilizing `let` bindings, we'd break code like `let mut x = false; false && { x = true; false };`. So to use `let` bindings in constants you need to change `&&` and `||` to `&` and `|` respectively.

57 files changed, 152 insertions, 360 deletions

diff --git a/src/test/ui/consts/const-block-non-item-statement-2.rs b/src/test/ui/consts/const-block-non-item-statement-2.rs
deleted file mode 100644
index 58a6cf6dcfd..00000000000
--- a/src/test/ui/consts/const-block-non-item-statement-2.rs
+++ /dev/null
@@ -1,18 +0,0 @@
-const A: usize = { 1; 2 };
-//~^ ERROR statements in constants are unstable
-
-const B: usize = { { } 2 };
-//~^ ERROR statements in constants are unstable
-
-macro_rules! foo {
-    () => (()) //~ ERROR statements in constants are unstable
-}
-const C: usize = { foo!(); 2 };
-
-const D: usize = { let x = 4; 2 };
-//~^ ERROR let bindings in constants are unstable
-//~| ERROR statements in constants are unstable
-//~| ERROR let bindings in constants are unstable
-//~| ERROR statements in constants are unstable
-
-pub fn main() {}
diff --git a/src/test/ui/consts/const-block-non-item-statement-2.stderr b/src/test/ui/consts/const-block-non-item-statement-2.stderr
deleted file mode 100644
index e0c61a953f5..00000000000
--- a/src/test/ui/consts/const-block-non-item-statement-2.stderr
+++ /dev/null
@@ -1,62 +0,0 @@
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:1:20
-   |
-LL | const A: usize = { 1; 2 };
-   |                    ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:4:20
-   |
-LL | const B: usize = { { } 2 };
-   |                    ^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:8:12
-   |
-LL |     () => (()) //~ ERROR statements in constants are unstable
-   |            ^^
-LL | }
-LL | const C: usize = { foo!(); 2 };
-   |                    ------- in this macro invocation
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:12:28
-   |
-LL | const D: usize = { let x = 4; 2 };
-   |                            ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:12:28
-   |
-LL | const D: usize = { let x = 4; 2 };
-   |                            ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:12:1
-   |
-LL | const D: usize = { let x = 4; 2 };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-2.rs:12:1
-   |
-LL | const D: usize = { let x = 4; 2 };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 7 previous errors
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/consts/const-block-non-item-statement-3.rs b/src/test/ui/consts/const-block-non-item-statement-3.rs
deleted file mode 100644
index 867840925b2..00000000000
--- a/src/test/ui/consts/const-block-non-item-statement-3.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-type Array = [u32; {  let x = 2; 5 }];
-//~^ ERROR let bindings in constants are unstable
-//~| ERROR statements in constants are unstable
-//~| ERROR let bindings in constants are unstable
-//~| ERROR statements in constants are unstable
-
-pub fn main() {}
diff --git a/src/test/ui/consts/const-block-non-item-statement-3.stderr b/src/test/ui/consts/const-block-non-item-statement-3.stderr
deleted file mode 100644
index 0a549bc0c8d..00000000000
--- a/src/test/ui/consts/const-block-non-item-statement-3.stderr
+++ /dev/null
@@ -1,35 +0,0 @@
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-3.rs:1:31
-   |
-LL | type Array = [u32; {  let x = 2; 5 }];
-   |                               ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-3.rs:1:31
-   |
-LL | type Array = [u32; {  let x = 2; 5 }];
-   |                               ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-3.rs:1:20
-   |
-LL | type Array = [u32; {  let x = 2; 5 }];
-   |                    ^^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement-3.rs:1:20
-   |
-LL | type Array = [u32; {  let x = 2; 5 }];
-   |                    ^^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 4 previous errors
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/consts/const-block-non-item-statement.rs b/src/test/ui/consts/const-block-non-item-statement.rs
index 2db9e2413e5..5ecf9a04984 100644
--- a/src/test/ui/consts/const-block-non-item-statement.rs
+++ b/src/test/ui/consts/const-block-non-item-statement.rs
@@ -1,9 +1,23 @@
+// compile-pass
+
 enum Foo {
     Bar = { let x = 1; 3 }
-    //~^ ERROR let bindings in constants are unstable
-    //~| ERROR statements in constants are unstable
-    //~| ERROR let bindings in constants are unstable
-    //~| ERROR statements in constants are unstable
 }
 
+
+const A: usize = { 1; 2 };
+
+const B: usize = { { } 2 };
+
+macro_rules! foo {
+    () => (())
+}
+
+const C: usize = { foo!(); 2 };
+
+const D: usize = { let x = 4; 2 };
+
+type Array = [u32; {  let x = 2; 5 }];
+type Array2 = [u32; { let mut x = 2; x = 3; x}];
+
 pub fn main() {}
diff --git a/src/test/ui/consts/const-block-non-item-statement.stderr b/src/test/ui/consts/const-block-non-item-statement.stderr
deleted file mode 100644
index f0d751e0756..00000000000
--- a/src/test/ui/consts/const-block-non-item-statement.stderr
+++ /dev/null
@@ -1,35 +0,0 @@
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement.rs:2:21
-   |
-LL |     Bar = { let x = 1; 3 }
-   |                     ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement.rs:2:21
-   |
-LL |     Bar = { let x = 1; 3 }
-   |                     ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement.rs:2:11
-   |
-LL |     Bar = { let x = 1; 3 }
-   |           ^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constants are unstable (see issue #48821)
-  --> $DIR/const-block-non-item-statement.rs:2:11
-   |
-LL |     Bar = { let x = 1; 3 }
-   |           ^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 4 previous errors
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.rs b/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.rs
index ba8d032367e..4d3c714481a 100644
--- a/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.rs
+++ b/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.rs
@@ -2,7 +2,6 @@
 // The test should never compile successfully
 
 #![feature(const_raw_ptr_deref)]
-#![feature(const_let)]
 
 use std::cell::UnsafeCell;
 
diff --git a/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.stderr b/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.stderr
index 6ca9d688bd0..be1be6c0600 100644
--- a/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.stderr
+++ b/src/test/ui/consts/const-eval/assign-to-static-within-other-static-2.stderr
@@ -1,5 +1,5 @@
 error[E0019]: static contains unimplemented expression type
-  --> $DIR/assign-to-static-within-other-static-2.rs:17:5
+  --> $DIR/assign-to-static-within-other-static-2.rs:16:5
    |
 LL |     *FOO.0.get() = 5; //~ ERROR contains unimplemented expression type
    |     ^^^^^^^^^^^^^^^^
diff --git a/src/test/ui/consts/const-eval/assign-to-static-within-other-static.rs b/src/test/ui/consts/const-eval/assign-to-static-within-other-static.rs
index 9fe17bfc6a0..b4c416b1c55 100644
--- a/src/test/ui/consts/const-eval/assign-to-static-within-other-static.rs
+++ b/src/test/ui/consts/const-eval/assign-to-static-within-other-static.rs
@@ -2,7 +2,6 @@
 // The test should never compile successfully
 
 #![feature(const_raw_ptr_deref)]
-#![feature(const_let)]
 
 use std::cell::UnsafeCell;
 
diff --git a/src/test/ui/consts/const-eval/assign-to-static-within-other-static.stderr b/src/test/ui/consts/const-eval/assign-to-static-within-other-static.stderr
index 2ab9765305f..31e49dc10ca 100644
--- a/src/test/ui/consts/const-eval/assign-to-static-within-other-static.stderr
+++ b/src/test/ui/consts/const-eval/assign-to-static-within-other-static.stderr
@@ -1,5 +1,5 @@
 error: cannot mutate statics in the initializer of another static
-  --> $DIR/assign-to-static-within-other-static.rs:11:5
+  --> $DIR/assign-to-static-within-other-static.rs:10:5
    |
 LL |     FOO = 5; //~ ERROR cannot mutate statics in the initializer of another static
    |     ^^^^^^^
diff --git a/src/test/ui/consts/const-eval/const_let.rs b/src/test/ui/consts/const-eval/const_let.rs
index 9e6952733bb..63321b91200 100644
--- a/src/test/ui/consts/const-eval/const_let.rs
+++ b/src/test/ui/consts/const-eval/const_let.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 fn main() {}
 
 struct FakeNeedsDrop;
diff --git a/src/test/ui/consts/const-eval/const_let.stderr b/src/test/ui/consts/const-eval/const_let.stderr
index e128ca07d86..00de97e6fb3 100644
--- a/src/test/ui/consts/const-eval/const_let.stderr
+++ b/src/test/ui/consts/const-eval/const_let.stderr
@@ -1,11 +1,11 @@
 error[E0019]: constant contains unimplemented expression type
-  --> $DIR/const_let.rs:15:55
+  --> $DIR/const_let.rs:13:55
    |
 LL | const Y: FakeNeedsDrop = { let mut x = FakeNeedsDrop; x = FakeNeedsDrop; x };
    |                                                       ^
 
 error[E0019]: constant contains unimplemented expression type
-  --> $DIR/const_let.rs:19:35
+  --> $DIR/const_let.rs:17:35
    |
 LL | const Z: () = { let mut x = None; x = Some(FakeNeedsDrop); };
    |                                   ^
diff --git a/src/test/ui/consts/const-eval/infinite_loop.rs b/src/test/ui/consts/const-eval/infinite_loop.rs
index 0d5530acc95..a2a45af7cb0 100644
--- a/src/test/ui/consts/const-eval/infinite_loop.rs
+++ b/src/test/ui/consts/const-eval/infinite_loop.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 fn main() {
     // Tests the Collatz conjecture with an incorrect base case (0 instead of 1).
     // The value of `n` will loop indefinitely (4 - 2 - 1 - 4).
diff --git a/src/test/ui/consts/const-eval/infinite_loop.stderr b/src/test/ui/consts/const-eval/infinite_loop.stderr
index 90d2159d7b5..422c2bab6ea 100644
--- a/src/test/ui/consts/const-eval/infinite_loop.stderr
+++ b/src/test/ui/consts/const-eval/infinite_loop.stderr
@@ -1,5 +1,5 @@
 error[E0019]: constant contains unimplemented expression type
-  --> $DIR/infinite_loop.rs:9:9
+  --> $DIR/infinite_loop.rs:7:9
    |
 LL | /         while n != 0 { //~ ERROR constant contains unimplemented expression type
 LL | |             n = if n % 2 == 0 { n/2 } else { 3*n + 1 };
@@ -8,7 +8,7 @@ LL | |         }
    | |_________^
 
 warning: Constant evaluating a complex constant, this might take some time
-  --> $DIR/infinite_loop.rs:6:18
+  --> $DIR/infinite_loop.rs:4:18
    |
 LL |       let _ = [(); {
    |  __________________^
@@ -21,7 +21,7 @@ LL | |     }];
    | |_____^
 
 error[E0080]: evaluation of constant value failed
-  --> $DIR/infinite_loop.rs:10:20
+  --> $DIR/infinite_loop.rs:8:20
    |
 LL |             n = if n % 2 == 0 { n/2 } else { 3*n + 1 };
    |                    ^^^^^^^^^^ duplicate interpreter state observed here, const evaluation will never terminate
diff --git a/src/test/ui/consts/const-eval/issue-52475.rs b/src/test/ui/consts/const-eval/issue-52475.rs
index 2e3d6fb9e84..aafdd5fe617 100644
--- a/src/test/ui/consts/const-eval/issue-52475.rs
+++ b/src/test/ui/consts/const-eval/issue-52475.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 fn main() {
     let _ = [(); {
         //~^ WARNING Constant evaluating a complex constant, this might take some time
diff --git a/src/test/ui/consts/const-eval/issue-52475.stderr b/src/test/ui/consts/const-eval/issue-52475.stderr
index 329ea8a21f9..4f1b2ab4c8f 100644
--- a/src/test/ui/consts/const-eval/issue-52475.stderr
+++ b/src/test/ui/consts/const-eval/issue-52475.stderr
@@ -1,5 +1,5 @@
 error[E0019]: constant contains unimplemented expression type
-  --> $DIR/issue-52475.rs:8:9
+  --> $DIR/issue-52475.rs:6:9
    |
 LL | /         while n < 5 { //~ ERROR constant contains unimplemented expression type
 LL | |             n = (n + 1) % 5; //~ ERROR evaluation of constant value failed
@@ -8,7 +8,7 @@ LL | |         }
    | |_________^
 
 warning: Constant evaluating a complex constant, this might take some time
-  --> $DIR/issue-52475.rs:4:18
+  --> $DIR/issue-52475.rs:2:18
    |
 LL |       let _ = [(); {
    |  __________________^
@@ -21,7 +21,7 @@ LL | |     }];
    | |_____^
 
 error[E0080]: evaluation of constant value failed
-  --> $DIR/issue-52475.rs:9:17
+  --> $DIR/issue-52475.rs:7:17
    |
 LL |             n = (n + 1) % 5; //~ ERROR evaluation of constant value failed
    |                 ^^^^^^^^^^^ duplicate interpreter state observed here, const evaluation will never terminate
diff --git a/src/test/ui/consts/const-eval/mod-static-with-const-fn.rs b/src/test/ui/consts/const-eval/mod-static-with-const-fn.rs
index 62090f4180d..32f0062168b 100644
--- a/src/test/ui/consts/const-eval/mod-static-with-const-fn.rs
+++ b/src/test/ui/consts/const-eval/mod-static-with-const-fn.rs
@@ -2,7 +2,6 @@
 // The test should never compile successfully
 
 #![feature(const_raw_ptr_deref)]
-#![feature(const_let)]
 
 use std::cell::UnsafeCell;
 
diff --git a/src/test/ui/consts/const-eval/mod-static-with-const-fn.stderr b/src/test/ui/consts/const-eval/mod-static-with-const-fn.stderr
index 12d6e3be40a..9fad6868d20 100644
--- a/src/test/ui/consts/const-eval/mod-static-with-const-fn.stderr
+++ b/src/test/ui/consts/const-eval/mod-static-with-const-fn.stderr
@@ -1,11 +1,11 @@
 error[E0019]: static contains unimplemented expression type
-  --> $DIR/mod-static-with-const-fn.rs:19:5
+  --> $DIR/mod-static-with-const-fn.rs:18:5
    |
 LL |     *FOO.0.get() = 5;
    |     ^^^^^^^^^^^^^^^^
 
 error[E0015]: calls in statics are limited to constant functions, tuple structs and tuple variants
-  --> $DIR/mod-static-with-const-fn.rs:22:5
+  --> $DIR/mod-static-with-const-fn.rs:21:5
    |
 LL |     foo();
    |     ^^^^^
diff --git a/src/test/ui/consts/const-eval/ub-upvars.rs b/src/test/ui/consts/const-eval/ub-upvars.rs
index 16df0c1b0cc..9b7bca6b72d 100644
--- a/src/test/ui/consts/const-eval/ub-upvars.rs
+++ b/src/test/ui/consts/const-eval/ub-upvars.rs
@@ -1,4 +1,4 @@
-#![feature(const_transmute,const_let)]
+#![feature(const_transmute)]
 #![allow(const_err)] // make sure we cannot allow away the errors tested here
 
 use std::mem;
diff --git a/src/test/ui/consts/const-fn-destructuring-arg.rs b/src/test/ui/consts/const-fn-destructuring-arg.rs
index 7f818079a19..dcf89f90e31 100644
--- a/src/test/ui/consts/const-fn-destructuring-arg.rs
+++ b/src/test/ui/consts/const-fn-destructuring-arg.rs
@@ -1,17 +1,7 @@
-// test that certain things are disallowed in constant functions
+// compile-pass
 
-#![feature(const_fn)]
-
-// no destructuring
-const fn i((
-            a,
-            //~^ ERROR arguments of constant functions can only be immutable by-value bindings
-            b
-            //~^ ERROR arguments of constant functions can only be immutable by-value bindings
-           ): (u32, u32)) -> u32 {
+const fn i((a, b): (u32, u32)) -> u32 {
     a + b
-    //~^ ERROR let bindings in constant functions are unstable
-    //~| ERROR let bindings in constant functions are unstable
 }
 
 fn main() {}
diff --git a/src/test/ui/consts/const-fn-destructuring-arg.stderr b/src/test/ui/consts/const-fn-destructuring-arg.stderr
deleted file mode 100644
index db63e830804..00000000000
--- a/src/test/ui/consts/const-fn-destructuring-arg.stderr
+++ /dev/null
@@ -1,35 +0,0 @@
-error[E0658]: arguments of constant functions can only be immutable by-value bindings (see issue #48821)
-  --> $DIR/const-fn-destructuring-arg.rs:7:13
-   |
-LL |             a,
-   |             ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: arguments of constant functions can only be immutable by-value bindings (see issue #48821)
-  --> $DIR/const-fn-destructuring-arg.rs:9:13
-   |
-LL |             b
-   |             ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-destructuring-arg.rs:12:5
-   |
-LL |     a + b
-   |     ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-destructuring-arg.rs:12:9
-   |
-LL |     a + b
-   |         ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 4 previous errors
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/consts/const-fn-not-safe-for-const.rs b/src/test/ui/consts/const-fn-not-safe-for-const.rs
index fe672e7b3e6..085ff5c58e6 100644
--- a/src/test/ui/consts/const-fn-not-safe-for-const.rs
+++ b/src/test/ui/consts/const-fn-not-safe-for-const.rs
@@ -27,13 +27,9 @@ const fn get_Y_addr() -> &'static u32 {
 }
 
 const fn get() -> u32 {
-    let x = 22; //~ ERROR let bindings in constant functions are unstable
-//~^ ERROR statements in constant functions
-    let y = 44; //~ ERROR let bindings in constant functions are unstable
-//~^ ERROR statements in constant functions
+    let x = 22;
+    let y = 44;
     x + y
-//~^ ERROR let bindings in constant functions are unstable
-//~| ERROR let bindings in constant functions are unstable
 }
 
 fn main() {}
diff --git a/src/test/ui/consts/const-fn-not-safe-for-const.stderr b/src/test/ui/consts/const-fn-not-safe-for-const.stderr
index 8cc4c385262..2003b137c27 100644
--- a/src/test/ui/consts/const-fn-not-safe-for-const.stderr
+++ b/src/test/ui/consts/const-fn-not-safe-for-const.stderr
@@ -16,55 +16,7 @@ error[E0013]: constant functions cannot refer to statics, use a constant instead
 LL |     &Y
    |     ^^
 
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:30:13
-   |
-LL |     let x = 22; //~ ERROR let bindings in constant functions are unstable
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:30:13
-   |
-LL |     let x = 22; //~ ERROR let bindings in constant functions are unstable
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:32:13
-   |
-LL |     let y = 44; //~ ERROR let bindings in constant functions are unstable
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: statements in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:32:13
-   |
-LL |     let y = 44; //~ ERROR let bindings in constant functions are unstable
-   |             ^^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:34:5
-   |
-LL |     x + y
-   |     ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error[E0658]: let bindings in constant functions are unstable (see issue #48821)
-  --> $DIR/const-fn-not-safe-for-const.rs:34:9
-   |
-LL |     x + y
-   |         ^
-   |
-   = help: add #![feature(const_let)] to the crate attributes to enable
-
-error: aborting due to 9 previous errors
+error: aborting due to 3 previous errors
 
-Some errors occurred: E0013, E0015, E0658.
+Some errors occurred: E0013, E0015.
 For more information about an error, try `rustc --explain E0013`.
diff --git a/src/test/ui/consts/const_let_assign.rs b/src/test/ui/consts/const_let_assign.rs
index a3c53a451e1..0b09b8469fd 100644
--- a/src/test/ui/consts/const_let_assign.rs
+++ b/src/test/ui/consts/const_let_assign.rs
@@ -1,7 +1,5 @@
 // compile-pass
 
-#![feature(const_let)]
-
 struct S(i32);
 
 const A: () = {
diff --git a/src/test/ui/consts/const_let_assign2.rs b/src/test/ui/consts/const_let_assign2.rs
index 0de7396501a..1c44237e49b 100644
--- a/src/test/ui/consts/const_let_assign2.rs
+++ b/src/test/ui/consts/const_let_assign2.rs
@@ -1,8 +1,5 @@
 // compile-pass
 
-#![feature(const_let)]
-#![feature(const_fn)]
-
 pub struct AA {
     pub data: [u8; 10],
 }
diff --git a/src/test/ui/consts/const_let_assign3.rs b/src/test/ui/consts/const_let_assign3.rs
index c2ed6cd85ab..cbe73923e9c 100644
--- a/src/test/ui/consts/const_let_assign3.rs
+++ b/src/test/ui/consts/const_let_assign3.rs
@@ -1,4 +1,3 @@
-#![feature(const_let)]
 #![feature(const_fn)]
 
 struct S {
@@ -18,6 +17,15 @@ const FOO: S = {
     s
 };
 
+type Array = [u32; {
+    let mut x = 2;
+    let y = &mut x;
+//~^ ERROR references in constants may only refer to immutable values
+    *y = 42;
+//~^ ERROR constant contains unimplemented expression type
+    *y
+}];
+
 fn main() {
     assert_eq!(FOO.state, 3);
 }
diff --git a/src/test/ui/consts/const_let_assign3.stderr b/src/test/ui/consts/const_let_assign3.stderr
index 0f294616d25..6649fb997cc 100644
--- a/src/test/ui/consts/const_let_assign3.stderr
+++ b/src/test/ui/consts/const_let_assign3.stderr
@@ -1,16 +1,28 @@
 error[E0019]: constant function contains unimplemented expression type
-  --> $DIR/const_let_assign3.rs:10:9
+  --> $DIR/const_let_assign3.rs:9:9
    |
 LL |         self.state = x;
    |         ^^^^^^^^^^^^^^
 
 error[E0017]: references in constants may only refer to immutable values
-  --> $DIR/const_let_assign3.rs:17:5
+  --> $DIR/const_let_assign3.rs:16:5
    |
 LL |     s.foo(3); //~ ERROR references in constants may only refer to immutable values
    |     ^ constants require immutable values
 
-error: aborting due to 2 previous errors
+error[E0017]: references in constants may only refer to immutable values
+  --> $DIR/const_let_assign3.rs:22:13
+   |
+LL |     let y = &mut x;
+   |             ^^^^^^ constants require immutable values
+
+error[E0019]: constant contains unimplemented expression type
+  --> $DIR/const_let_assign3.rs:24:5
+   |
+LL |     *y = 42;
+   |     ^^^^^^^
+
+error: aborting due to 4 previous errors
 
 Some errors occurred: E0017, E0019.
 For more information about an error, try `rustc --explain E0017`.
diff --git a/src/test/ui/consts/const_let_eq.rs b/src/test/ui/consts/const_let_eq.rs
index 8739cb80e94..a2364c392f2 100644
--- a/src/test/ui/consts/const_let_eq.rs
+++ b/src/test/ui/consts/const_let_eq.rs
@@ -1,5 +1,3 @@
-#![feature(const_let, const_fn)]
-
 // run-pass
 
 struct Foo<T>(T);
diff --git a/src/test/ui/consts/const_let_eq_float.rs b/src/test/ui/consts/const_let_eq_float.rs
index 2c7262df367..c48f54e567b 100644
--- a/src/test/ui/consts/const_let_eq_float.rs
+++ b/src/test/ui/consts/const_let_eq_float.rs
@@ -1,6 +1,6 @@
 // compile-pass
 
-#![feature(const_let, const_fn)]
+#![feature(const_fn)]
 
 struct Foo<T>(T);
 struct Bar<T> { x: T }
diff --git a/src/test/ui/consts/const_let_irrefutable.rs b/src/test/ui/consts/const_let_irrefutable.rs
new file mode 100644
index 00000000000..424a16f7ed3
--- /dev/null
+++ b/src/test/ui/consts/const_let_irrefutable.rs
@@ -0,0 +1,11 @@
+// compile-pass
+
+fn main() {}
+
+const fn tup((a, b): (i32, i32)) -> i32 {
+    a + b
+}
+
+const fn array([a, b]: [i32; 2]) -> i32 {
+    a + b
+}
diff --git a/src/test/ui/consts/const_let_refutable.rs b/src/test/ui/consts/const_let_refutable.rs
new file mode 100644
index 00000000000..345f682868f
--- /dev/null
+++ b/src/test/ui/consts/const_let_refutable.rs
@@ -0,0 +1,5 @@
+fn main() {}
+
+const fn slice([a, b]: &[i32]) -> i32 { //~ ERROR refutable pattern in function argument
+    a + b
+}
diff --git a/src/test/ui/consts/const_let_refutable.stderr b/src/test/ui/consts/const_let_refutable.stderr
new file mode 100644
index 00000000000..c5d2ba02a70
--- /dev/null
+++ b/src/test/ui/consts/const_let_refutable.stderr
@@ -0,0 +1,9 @@
+error[E0005]: refutable pattern in function argument: `&[]` not covered
+  --> $DIR/const_let_refutable.rs:3:16
+   |
+LL | const fn slice([a, b]: &[i32]) -> i32 { //~ ERROR refutable pattern in function argument
+   |                ^^^^^^ pattern `&[]` not covered
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0005`.
diff --git a/src/test/ui/consts/const_short_circuit.rs b/src/test/ui/consts/const_short_circuit.rs
index cc49e4696e5..1e7b7ed3193 100644
--- a/src/test/ui/consts/const_short_circuit.rs
+++ b/src/test/ui/consts/const_short_circuit.rs
@@ -1,4 +1,4 @@
-#![feature(underscore_const_names, const_let)]
+#![feature(underscore_const_names)]
 
 const _: bool = false && false;
 const _: bool = true && false;
diff --git a/src/test/ui/consts/dangling-alloc-id-ice.rs b/src/test/ui/consts/dangling-alloc-id-ice.rs
index 695d33b6908..dbc50f1fbd4 100644
--- a/src/test/ui/consts/dangling-alloc-id-ice.rs
+++ b/src/test/ui/consts/dangling-alloc-id-ice.rs
@@ -1,7 +1,5 @@
 // https://github.com/rust-lang/rust/issues/55223
 
-#![feature(const_let)]
-
 union Foo<'a> {
     y: &'a (),
     long_live_the_unit: &'static (),
diff --git a/src/test/ui/consts/dangling-alloc-id-ice.stderr b/src/test/ui/consts/dangling-alloc-id-ice.stderr
index a5fa88e5e68..2cd8711f03d 100644
--- a/src/test/ui/consts/dangling-alloc-id-ice.stderr
+++ b/src/test/ui/consts/dangling-alloc-id-ice.stderr
@@ -1,5 +1,5 @@
 error: any use of this value will cause an error
-  --> $DIR/dangling-alloc-id-ice.rs:10:1
+  --> $DIR/dangling-alloc-id-ice.rs:8:1
    |
 LL | / const FOO: &() = { //~ ERROR any use of this value will cause an error
 LL | |     let y = ();
diff --git a/src/test/ui/consts/dangling_raw_ptr.rs b/src/test/ui/consts/dangling_raw_ptr.rs
index 7fc773412f2..c2d8e6d421a 100644
--- a/src/test/ui/consts/dangling_raw_ptr.rs
+++ b/src/test/ui/consts/dangling_raw_ptr.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 const FOO: *const u32 = { //~ ERROR any use of this value will cause an error
     let x = 42;
     &x
diff --git a/src/test/ui/consts/dangling_raw_ptr.stderr b/src/test/ui/consts/dangling_raw_ptr.stderr
index 3b20936f8ae..091f1f785cb 100644
--- a/src/test/ui/consts/dangling_raw_ptr.stderr
+++ b/src/test/ui/consts/dangling_raw_ptr.stderr
@@ -1,5 +1,5 @@
 error: any use of this value will cause an error
-  --> $DIR/dangling_raw_ptr.rs:3:1
+  --> $DIR/dangling_raw_ptr.rs:1:1
    |
 LL | / const FOO: *const u32 = { //~ ERROR any use of this value will cause an error
 LL | |     let x = 42;
diff --git a/src/test/ui/consts/min_const_fn/min_const_fn.nll.stderr b/src/test/ui/consts/min_const_fn/min_const_fn.nll.stderr
index 551bc57e5ae..91b076097b0 100644
--- a/src/test/ui/consts/min_const_fn/min_const_fn.nll.stderr
+++ b/src/test/ui/consts/min_const_fn/min_const_fn.nll.stderr
@@ -112,12 +112,6 @@ error: `if`, `match`, `&&` and `||` are not stable in const fn
 LL | const fn foo30_5(b: bool) { while b { } } //~ ERROR not stable in const fn
    |                             ^^^^^^^^^^^
 
-error: local variables in const fn are unstable
-  --> $DIR/min_const_fn.rs:99:34
-   |
-LL | const fn foo30_6() -> bool { let x = true; x } //~ ERROR local variables in const fn
-   |                                  ^
-
 error: `if`, `match`, `&&` and `||` are not stable in const fn
   --> $DIR/min_const_fn.rs:100:44
    |
@@ -220,7 +214,7 @@ error: function pointers in const fn are unstable
 LL | const fn no_fn_ptrs2() -> fn() { fn foo() {} foo }
    |                           ^^^^
 
-error: aborting due to 35 previous errors
+error: aborting due to 34 previous errors
 
 Some errors occurred: E0493, E0515.
 For more information about an error, try `rustc --explain E0493`.
diff --git a/src/test/ui/consts/min_const_fn/min_const_fn.rs b/src/test/ui/consts/min_const_fn/min_const_fn.rs
index 238b5f7e310..05cf3d5f1f1 100644
--- a/src/test/ui/consts/min_const_fn/min_const_fn.rs
+++ b/src/test/ui/consts/min_const_fn/min_const_fn.rs
@@ -96,7 +96,7 @@ const fn foo30_2(x: *mut u32) -> usize { x as usize }
 const fn foo30_4(b: bool) -> usize { if b { 1 } else { 42 } }
 //~^ ERROR `if`, `match`, `&&` and `||` are not stable in const fn
 const fn foo30_5(b: bool) { while b { } } //~ ERROR not stable in const fn
-const fn foo30_6() -> bool { let x = true; x } //~ ERROR local variables in const fn
+const fn foo30_6() -> bool { let x = true; x }
 const fn foo36(a: bool, b: bool) -> bool { a && b }
 //~^ ERROR `if`, `match`, `&&` and `||` are not stable in const fn
 const fn foo37(a: bool, b: bool) -> bool { a || b }
diff --git a/src/test/ui/consts/min_const_fn/min_const_fn.stderr b/src/test/ui/consts/min_const_fn/min_const_fn.stderr
index 1c68df513b6..2cae714fbf7 100644
--- a/src/test/ui/consts/min_const_fn/min_const_fn.stderr
+++ b/src/test/ui/consts/min_const_fn/min_const_fn.stderr
@@ -112,12 +112,6 @@ error: `if`, `match`, `&&` and `||` are not stable in const fn
 LL | const fn foo30_5(b: bool) { while b { } } //~ ERROR not stable in const fn
    |                             ^^^^^^^^^^^
 
-error: local variables in const fn are unstable
-  --> $DIR/min_const_fn.rs:99:34
-   |
-LL | const fn foo30_6() -> bool { let x = true; x } //~ ERROR local variables in const fn
-   |                                  ^
-
 error: `if`, `match`, `&&` and `||` are not stable in const fn
   --> $DIR/min_const_fn.rs:100:44
    |
@@ -208,6 +202,6 @@ error: function pointers in const fn are unstable
 LL | const fn no_fn_ptrs2() -> fn() { fn foo() {} foo }
    |                           ^^^^
 
-error: aborting due to 35 previous errors
+error: aborting due to 34 previous errors
 
 For more information about this error, try `rustc --explain E0493`.
diff --git a/src/test/ui/consts/min_const_fn/mutable_borrow.rs b/src/test/ui/consts/min_const_fn/mutable_borrow.rs
index 3dd76b630a8..89acfea6ed8 100644
--- a/src/test/ui/consts/min_const_fn/mutable_borrow.rs
+++ b/src/test/ui/consts/min_const_fn/mutable_borrow.rs
@@ -1,6 +1,6 @@
 const fn mutable_ref_in_const() -> u8 {
-    let mut a = 0; //~ ERROR local variables in const fn
-    let b = &mut a;
+    let mut a = 0;
+    let b = &mut a; //~ ERROR mutable references in const fn
     *b
 }
 
@@ -8,8 +8,8 @@ struct X;
 
 impl X {
     const fn inherent_mutable_ref_in_const() -> u8 {
-        let mut a = 0; //~ ERROR local variables in const fn
-        let b = &mut a;
+        let mut a = 0;
+        let b = &mut a; //~ ERROR mutable references in const fn
         *b
     }
 }
diff --git a/src/test/ui/consts/min_const_fn/mutable_borrow.stderr b/src/test/ui/consts/min_const_fn/mutable_borrow.stderr
index fa46f5c804f..5ce0f30dc6e 100644
--- a/src/test/ui/consts/min_const_fn/mutable_borrow.stderr
+++ b/src/test/ui/consts/min_const_fn/mutable_borrow.stderr
@@ -1,14 +1,14 @@
-error: local variables in const fn are unstable
-  --> $DIR/mutable_borrow.rs:2:9
+error: mutable references in const fn are unstable
+  --> $DIR/mutable_borrow.rs:3:9
    |
-LL |     let mut a = 0; //~ ERROR local variables in const fn
-   |         ^^^^^
+LL |     let b = &mut a; //~ ERROR mutable references in const fn
+   |         ^
 
-error: local variables in const fn are unstable
-  --> $DIR/mutable_borrow.rs:11:13
+error: mutable references in const fn are unstable
+  --> $DIR/mutable_borrow.rs:12:13
    |
-LL |         let mut a = 0; //~ ERROR local variables in const fn
-   |             ^^^^^
+LL |         let b = &mut a; //~ ERROR mutable references in const fn
+   |             ^
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/consts/partial_qualif.rs b/src/test/ui/consts/partial_qualif.rs
index 4ce41f80f82..32c68e69f4b 100644
--- a/src/test/ui/consts/partial_qualif.rs
+++ b/src/test/ui/consts/partial_qualif.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 use std::cell::Cell;
 
 const FOO: &(Cell<usize>, bool) = {
diff --git a/src/test/ui/consts/partial_qualif.stderr b/src/test/ui/consts/partial_qualif.stderr
index d695f64e2c3..967fb83b78b 100644
--- a/src/test/ui/consts/partial_qualif.stderr
+++ b/src/test/ui/consts/partial_qualif.stderr
@@ -1,5 +1,5 @@
 error[E0492]: cannot borrow a constant which may contain interior mutability, create a static instead
-  --> $DIR/partial_qualif.rs:8:5
+  --> $DIR/partial_qualif.rs:6:5
    |
 LL |     &{a} //~ ERROR cannot borrow a constant which may contain interior mutability
    |     ^^^^
diff --git a/src/test/ui/consts/projection_qualif.rs b/src/test/ui/consts/projection_qualif.rs
index 5863429a2f2..dedb7db5920 100644
--- a/src/test/ui/consts/projection_qualif.rs
+++ b/src/test/ui/consts/projection_qualif.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 use std::cell::Cell;
 
 const FOO: &u32 = {
diff --git a/src/test/ui/consts/projection_qualif.stderr b/src/test/ui/consts/projection_qualif.stderr
index cc3635a979b..410c51c4b54 100644
--- a/src/test/ui/consts/projection_qualif.stderr
+++ b/src/test/ui/consts/projection_qualif.stderr
@@ -1,17 +1,17 @@
 error[E0017]: references in constants may only refer to immutable values
-  --> $DIR/projection_qualif.rs:8:27
+  --> $DIR/projection_qualif.rs:6:27
    |
 LL |         let b: *mut u32 = &mut a; //~ ERROR may only refer to immutable values
    |                           ^^^^^^ constants require immutable values
 
 error[E0019]: constant contains unimplemented expression type
-  --> $DIR/projection_qualif.rs:9:18
+  --> $DIR/projection_qualif.rs:7:18
    |
 LL |         unsafe { *b = 5; } //~ ERROR dereferencing raw pointers in constants
    |                  ^^^^^^
 
 error[E0658]: dereferencing raw pointers in constants is unstable (see issue #51911)
-  --> $DIR/projection_qualif.rs:9:18
+  --> $DIR/projection_qualif.rs:7:18
    |
 LL |         unsafe { *b = 5; } //~ ERROR dereferencing raw pointers in constants
    |                  ^^^^^^
diff --git a/src/test/ui/consts/promote_const_let.nll.stderr b/src/test/ui/consts/promote_const_let.nll.stderr
index d8749bb5fd9..e6ee1523a3b 100644
--- a/src/test/ui/consts/promote_const_let.nll.stderr
+++ b/src/test/ui/consts/promote_const_let.nll.stderr
@@ -1,5 +1,5 @@
 error[E0597]: `y` does not live long enough
-  --> $DIR/promote_const_let.rs:6:9
+  --> $DIR/promote_const_let.rs:4:9
    |
 LL |     let x: &'static u32 = {
    |            ------------ type annotation requires that `y` is borrowed for `'static`
@@ -9,6 +9,21 @@ LL |         &y //~ ERROR does not live long enough
 LL |     };
    |     - `y` dropped here while still borrowed
 
-error: aborting due to previous error
+error[E0716]: temporary value dropped while borrowed
+  --> $DIR/promote_const_let.rs:6:28
+   |
+LL |       let x: &'static u32 = &{ //~ ERROR does not live long enough
+   |  ____________------------____^
+   | |            |
+   | |            type annotation requires that borrow lasts for `'static`
+LL | |         let y = 42;
+LL | |         y
+LL | |     };
+   | |_____^ creates a temporary which is freed while still in use
+LL |   }
+   |   - temporary value is freed at the end of this statement
+
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0597`.
+Some errors occurred: E0597, E0716.
+For more information about an error, try `rustc --explain E0597`.
diff --git a/src/test/ui/consts/promote_const_let.rs b/src/test/ui/consts/promote_const_let.rs
index 8de9b00eb11..a8a6d4d99c6 100644
--- a/src/test/ui/consts/promote_const_let.rs
+++ b/src/test/ui/consts/promote_const_let.rs
@@ -1,8 +1,10 @@
-#![feature(const_let)]
-
 fn main() {
     let x: &'static u32 = {
         let y = 42;
         &y //~ ERROR does not live long enough
     };
+    let x: &'static u32 = &{ //~ ERROR does not live long enough
+        let y = 42;
+        y
+    };
 }
diff --git a/src/test/ui/consts/promote_const_let.stderr b/src/test/ui/consts/promote_const_let.stderr
index 6bbb7495fb0..d37bd491860 100644
--- a/src/test/ui/consts/promote_const_let.stderr
+++ b/src/test/ui/consts/promote_const_let.stderr
@@ -1,5 +1,5 @@
 error[E0597]: `y` does not live long enough
-  --> $DIR/promote_const_let.rs:6:10
+  --> $DIR/promote_const_let.rs:4:10
    |
 LL |         &y //~ ERROR does not live long enough
    |          ^ borrowed value does not live long enough
@@ -8,6 +8,20 @@ LL |     };
    |
    = note: borrowed value must be valid for the static lifetime...
 
-error: aborting due to previous error
+error[E0597]: borrowed value does not live long enough
+  --> $DIR/promote_const_let.rs:6:28
+   |
+LL |       let x: &'static u32 = &{ //~ ERROR does not live long enough
+   |  ____________________________^
+LL | |         let y = 42;
+LL | |         y
+LL | |     };
+   | |_____^ temporary value does not live long enough
+LL |   }
+   |   - temporary value only lives until here
+   |
+   = note: borrowed value must be valid for the static lifetime...
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0597`.
diff --git a/src/test/ui/consts/qualif_overwrite.rs b/src/test/ui/consts/qualif_overwrite.rs
index 806a74ee453..430eea37de7 100644
--- a/src/test/ui/consts/qualif_overwrite.rs
+++ b/src/test/ui/consts/qualif_overwrite.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 use std::cell::Cell;
 
 // this is overly conservative. The reset to `None` should clear `a` of all qualifications
diff --git a/src/test/ui/consts/qualif_overwrite.stderr b/src/test/ui/consts/qualif_overwrite.stderr
index 4fac64bf806..30479139e31 100644
--- a/src/test/ui/consts/qualif_overwrite.stderr
+++ b/src/test/ui/consts/qualif_overwrite.stderr
@@ -1,5 +1,5 @@
 error[E0492]: cannot borrow a constant which may contain interior mutability, create a static instead
-  --> $DIR/qualif_overwrite.rs:12:5
+  --> $DIR/qualif_overwrite.rs:10:5
    |
 LL |     &{a} //~ ERROR cannot borrow a constant which may contain interior mutability
    |     ^^^^
diff --git a/src/test/ui/consts/qualif_overwrite_2.rs b/src/test/ui/consts/qualif_overwrite_2.rs
index 29557a3da47..fa79b5c14a7 100644
--- a/src/test/ui/consts/qualif_overwrite_2.rs
+++ b/src/test/ui/consts/qualif_overwrite_2.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 use std::cell::Cell;
 
 // const qualification is not smart enough to know about fields and always assumes that there might
diff --git a/src/test/ui/consts/qualif_overwrite_2.stderr b/src/test/ui/consts/qualif_overwrite_2.stderr
index 181b728c7b7..8276db99a12 100644
--- a/src/test/ui/consts/qualif_overwrite_2.stderr
+++ b/src/test/ui/consts/qualif_overwrite_2.stderr
@@ -1,5 +1,5 @@
 error[E0492]: cannot borrow a constant which may contain interior mutability, create a static instead
-  --> $DIR/qualif_overwrite_2.rs:10:5
+  --> $DIR/qualif_overwrite_2.rs:8:5
    |
 LL |     &{a.0} //~ ERROR cannot borrow a constant which may contain interior mutability
    |     ^^^^^^
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref2.rs b/src/test/ui/consts/static_mut_containing_mut_ref2.rs
index 4180b1e295a..ef378fa8451 100644
--- a/src/test/ui/consts/static_mut_containing_mut_ref2.rs
+++ b/src/test/ui/consts/static_mut_containing_mut_ref2.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 static mut STDERR_BUFFER_SPACE: u8 = 0;
 
 pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref2.stderr b/src/test/ui/consts/static_mut_containing_mut_ref2.stderr
index f0ae1545056..72186571d69 100644
--- a/src/test/ui/consts/static_mut_containing_mut_ref2.stderr
+++ b/src/test/ui/consts/static_mut_containing_mut_ref2.stderr
@@ -1,11 +1,11 @@
 error[E0017]: references in statics may only refer to immutable values
-  --> $DIR/static_mut_containing_mut_ref2.rs:5:46
+  --> $DIR/static_mut_containing_mut_ref2.rs:3:46
    |
 LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^ statics require immutable values
 
 error[E0019]: static contains unimplemented expression type
-  --> $DIR/static_mut_containing_mut_ref2.rs:5:45
+  --> $DIR/static_mut_containing_mut_ref2.rs:3:45
    |
 LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
    |                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref3.rs b/src/test/ui/consts/static_mut_containing_mut_ref3.rs
index 0bc7faa9afd..c24c7e27920 100644
--- a/src/test/ui/consts/static_mut_containing_mut_ref3.rs
+++ b/src/test/ui/consts/static_mut_containing_mut_ref3.rs
@@ -1,5 +1,3 @@
-#![feature(const_let)]
-
 static mut FOO: (u8, u8) = (42, 43);
 
 static mut BAR: () = unsafe { FOO.0 = 99; };
diff --git a/src/test/ui/consts/static_mut_containing_mut_ref3.stderr b/src/test/ui/consts/static_mut_containing_mut_ref3.stderr
index cae53c6fee9..e88e49b097a 100644
--- a/src/test/ui/consts/static_mut_containing_mut_ref3.stderr
+++ b/src/test/ui/consts/static_mut_containing_mut_ref3.stderr
@@ -1,5 +1,5 @@
 error[E0080]: could not evaluate static initializer
-  --> $DIR/static_mut_containing_mut_ref3.rs:5:31
+  --> $DIR/static_mut_containing_mut_ref3.rs:3:31
    |
 LL | static mut BAR: () = unsafe { FOO.0 = 99; };
    |                               ^^^^^^^^^^ tried to modify a static's initial value from another static's initializer