No method `enter` on InferCtxtBuilder

[mejrs]

see https://rustc-dev-guide.rust-lang.org/type-inference.html#creating-an-inference-context

This enter method was removed a while ago, but the documentation is still there

[fmease]

The enter method might have been moved to InheritedBuilder (see InheritedBuilder::enter) if I read things correctly.

[Noratrieb]

tcx.infer_ctxt().enter(|infcx| {
    // Use the inference context `infcx` here.
})

is now used as

let infcx = tcx.infer_ctxt().build();
// Use the inference context `infcx` here.

[Noratrieb]

It also doesn't have a lifetime anymore except for 'tcx.