Generate obligations when possible instead of rejecting with ambiguity #139955
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A new mode of type relating is introduced so that obligations are generated instead of outright rejecting projection clauses. This allows project candidates that are sourced from more than one predicates, such as supertrait bounds, provided that they do not conflict each other.
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r? types |
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This sort of change requires a lot of care as previous attempts to add deferred projection equality (as in, the thing you're partially implementing) have caused overflow errors. See #96912 for the last attempt in the old solver. cc the relevant zulip thread, I would like to keep discussions about the issue (and its solution) in one place https://rust-lang.zulipchat.com/#narrow/channel/144729-t-types/topic/Make.20projection.20out.20of.20associated.20type/with/512793342 |
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A new mode of type relating is introduced so that obligations are generated instead of outright rejecting projection clauses. This allows project candidates that are sourced from more than one predicates, such as supertrait bounds, provided that they do not conflict each other.