Remove unsafe block deemed unnecessary by compiler

[thierrymarianne]

Hello 👋🏼,

Please see this minor issue about the unsafe keyword originating in a warning message at compilation :
fixes #2781

Examples:

• Scryer Prolog build
• Some other build

[Skgland]

I think the addr_of_mut!here used to be unsafe, so the unsafe block is necessary in older rust versions. Did you check whether the warning is there when using the mrsv as defined in the Cargo.toml and tested in CI?

Or rather does this compile without the unsafe block when using the msrv compiler?

I think the relevant change in rust would be rust-lang/rust#125834

[thierrymarianne]

Thank you, I didn't know the minimal supported Rust version was 1.77.

I'm checking these changes right now.

[thierrymarianne]

Closing this issue as it fails the build for rust v1.77.
Sorry for the noise.

[thierrymarianne]

Would it make sense to add basic contributing guidelines (in the vein of what is suggested from CONTRIBUTING.md) to the repository where requirements like

checking against minimal supported Rust version

could be listed?

I also notice now the README contains the following:

Scryer Prolog must be built with Rust 1.70 and up.