Guess what, their system language ESPOL, an Algol derivative later replaced by NEWP, already had unsafe code blocks.

Binaries that made use of unsafe were tainted and required that the admin would given them permission to execute.

This almost 10 years before C was created.

That would mean ruling out a whole lot of performance-critical software (including that written in unsafe Rust). Be careful what you wish for.

Doesn't matter what kinds of checks you put in. It might matter what kind of runtime you have, but a runtime isn't a language, is it? We're talking about the language, and any language sufficiently expressive to allow you to say "loop until you are done" instead of "loop precisely 20 times" is inherently unsafe.