tests: Add ui/higher-ranked/trait-bounds/normalize-generic-arg.rs

[Enselic]

This adds a regression test for an ICE "accidentally" fixed by #101947 that does not add a test for this particular case.

Closes #107564.

I have confirmed the added test code fails with nightly-2023-01-09 (and passes with nightly-2023-01-10 and of course recent nightly).

[rustbot]

r? @oli-obk

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[compiler-errors]

This probably shouldn't be added as a test, since it's exercising behavior that we may not expect to work on the new trait solver. Type inferfence in higher-ranked associated types is kinda busted.

If you really want to add this test, then you should probably add two explicit revisions for the old and new trait solver. Grep the ui test suite for some lines to steal: //@ revisions: current next.

Also, this test name is not really complete. It should mention something like higher-ranked. Maybe rigid-equate-projections-in-higher-ranked-fn-signature.

[Enselic]

This probably shouldn't be added as a test, since it's exercising behavior that we may not expect to work on the new trait solver. Type inferfence in higher-ranked associated types is kinda busted.

My main goal is to close #107564. Personally I'm completely fine with closing it with motivation "we don't want a test for this case".

But for now I updated the test.

If you really want to add this test, then you should probably add two explicit revisions for the old and new trait solver. Grep the ui test suite for some lines to steal: //@ revisions: current next.

Done!

Also, this test name is not really complete. It should mention something like higher-ranked. Maybe rigid-equate-projections-in-higher-ranked-fn-signature.

I thought it was sufficient that it was put in a dir called higher-ranked. But your name is much better than mine regardless. Done!

[fmease]

(minor) either // (preferably) or //!. rn, this is "documenting" the trait, not the crate

[compiler-errors]

@bors r+

[bors]

📌 Commit 1293ef7 has been approved by compiler-errors

It is now in the queue for this repository.

[compiler-errors]

@bors rollup