0fcabec620
Coherence negative impls implied bounds
Fixes #93875
This PR is rebased on top of #100789 and it would need to include that one which is already r+ed.
r? ``@nikomatsakis``
cc ``@lcnr`` (which I've talked about 3222f420d9, I guess after you finish your reordering of modules and work with OutlivesEnvironmentEnv this commit can just be reverted).
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.