Add a test for the new type_name intrinsic.

[ecstatic-morse]

Addresses this comment from @RalfJung.

This makes the type_name intrinsic call librustc_mir::interpret::type_name instead of Ty::to_string.

I used the implementation of eval_const_to_op as a reference.

This now adds a test for the type_name intrinsic and removes the miri impl in favor of the in-core one.

[oli-obk]

I'd prefer to wait for rust-lang/rust#61399 to get merged and then remove the impl here

[RalfJung]

Okay. @ecstatic-morse could you reduce this PR to just the test case, and remove the intrinsic implementation? We can then merge that once the Rust PR lands.

[ecstatic-morse]

@RalfJung Done!

[RalfJung]

Could you also remove the implementation of the intrinsic from src/intrinsic.rs? It should not be needed any more now that we have a rustc-side implementation. You'll have to update rust-version to point to the latest commit from upstream rustc though.

And please rebase onto current master.

[RalfJung]

Oh actually never mind, rust-lang/rust#61498 did not land yet.

[RalfJung]

Tests are failing though:

thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `"std::option::Option<i32>"`,
 right: `"core::option::Option<i32>"`', $DIR/intrinsics.rs:14:5

[oli-obk]

They will keep failing without a bump of the rustc version we're using in CI

[ecstatic-morse]

I'll retrigger a CI run when rust-lang/rust#61498 lands.

[RalfJung]

You'll also have to update the rust-version file -- we are pinning the version that CI uses.

[ecstatic-morse]

@RalfJung

I updated rust-version to the latest nightly and Travis is green.