Auto merge of #149728 - mu001999-contrib:fix/149695, r=jdonszelmann

Emit ForbiddenBound fatally if meeting complex bound



Fixes rust-lang/rust#149695

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Bounds in binders are denied, hir items won't contain and index them. But nested items in the bounds will still be lowered to hir. And their parents, i.e., the block in bounds is not in hir. So that ICE happens when error handling requires visiting hir parents.

~~This PR collects hirless def ids and skips them when iterating parents.~~

~~This PR checks such bounds used in higher ranked binders and emit error `ForbiddenBound` when parsing. And make sure no such bounds appear in hir.~~

This PR emits this error fatally if meeting complex bound.

Author: bors