Weird error message for non-const const fns

[brson]

const fn foo() { panic!() }

fn main() { }

   Compiling playground v0.0.1 (/playground)
error: can only call other `min_const_fn` within a `min_const_fn`
 --> src/main.rs:1:18
  |
1 | const fn foo() { panic!() }
  |                  ^^^^^^^^
  |
  = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

The name min_const_fn seems meaningless to an end user. It should say something like "only call const functions within const functions."