rust-lang/rust#140748 will require us to adjust our format_args! lowering

[Veykril]

rust-lang/rust#140748
It removes the UnsafeArg token from the constructor, we need to mimic that and gate on the toolchain version

[ChayimFriedman2]

Thinking about it, why do we even need to mimic rustc with lowering of format_args! exactly? As long as we make sure we have all the formatting traits and expressions it should be fine, after all we don't actually format anything.

[Veykril]

We do make use of the formatting output for mir building / eval. We try to render the debug impl for things on hover for example (though its mostly broken due to us failing in various places in std at the moment.

[ShoyuVanilla]

The mentioned PR generates super let args = ... while expanding format_args!
Do we need super let to properly handle temporal lifetimes for mir building, as we don't have it yet?

[Veykril]

We might? The main immediate problem here is that we just need to fix up the lowering to prevent us from generating diagnostics for our desugared code (as that will cause log spamming again). More of our mir eval is semi broken right now anyways due to lack of support for a bunch of things.