error[E0080]: evaluation of constant value failed --> $DIR/issue-88434-minimal-example.rs:11:5 | LL | const _CONST: &() = &f(&|_| {}); | ---------- inside `_CONST` at $DIR/issue-88434-minimal-example.rs:3:22 ... LL | panic!() | ^^^^^^^^ | | | the evaluated program panicked at 'explicit panic', $DIR/issue-88434-minimal-example.rs:11:5 | inside `f::<[closure@$DIR/issue-88434-minimal-example.rs:3:25: 3:28]>` at $SRC_DIR/std/src/panic.rs:LL:COL | = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info) error: any use of this value will cause an error --> $DIR/issue-88434-minimal-example.rs:3:21 | LL | const _CONST: &() = &f(&|_| {}); | ----------------- ^^^^^^^^^^^ referenced constant has errors | = note: `#[deny(const_err)]` on by default = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! = note: for more information, see issue #71800 error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0080`. Future incompatibility report: Future breakage diagnostic: error: any use of this value will cause an error --> $DIR/issue-88434-minimal-example.rs:3:21 | LL | const _CONST: &() = &f(&|_| {}); | ----------------- ^^^^^^^^^^^ referenced constant has errors | = note: `#[deny(const_err)]` on by default = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! = note: for more information, see issue #71800