Update closure printing

[arora-aman]

Check #17

[arora-aman]

This should be a preliminary PR before #4

[arora-aman]

Check rust-lang/rust@ee88fc1 to see how to check -Z flags.

From the looks of it, for our purposes self.tcx.sess.verbose() will be more concise.

[arora-aman]

The error is printed from
Display from Ty is implemented in pretty.rs

This needs to be updated: https://doc.rust-lang.org/nightly/nightly-rustc/src/rustc_middle/ty/print/pretty.rs.html#667

[arora-aman]

closed by rust-lang/rust#77069