A policy is required regarding rust toolchain and error messages

[newca12]

#2446 get merged to fix an error message that was correct with Rust v1.41.0
Was it intentional ?
Rust messages are improved at each release but the book toolchain stick to v1.41.0
So what error messages should we use ?
Whatever the choice is, I guess we need at least to be consistent.

[steveklabnik]

The book should use the version of rust listed in https://github.com/rust-lang/book/blob/master/rust-toolchain

Which is currently 1.41.

Yes, I made a mistake there, I didn't realize it had changed between versions.

Fixing that bug should probably be "update everything to the latest Rust" rather than reverting, though.

[newca12]

I have a doubt so just in case you forgot, may I just remind you @carols10cents made update-rustc.sh to generate automatically all output.txt.
Just quoting her from #2231 "We can automatically update compiler errors for new Rust versions all at once to be less confusing for readers using newer compiler versions".
Using update-rustc.sh with 1.41 toolchain we can see that a few files have diverged.
Using update-rustc.sh with 1.46 toolchain we can see that 65/137 files changes (mostly for the better)
I hope this will help you to make an informed decision about updating everything or not.

[carols10cents]

The policy is that I will run the script to update to the latest stable when I have time to do so, as I am doing in #2518. Thanks!