Return early when treating ambiguous cycles#48
Return early when treating ambiguous cycles#48nikomatsakis merged 2 commits intorust-lang:masterfrom
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| answer = actual_answer; |
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is it possible to make a test for this? or is that test basically just in your PR for #12?
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Well that's funny because in fact if I provide a test for that and deactivate the fix, the test program will not even load because of the overlap check which will loop forever. So I was indeed relying on this behaviour to test the fix in my PR for #12 (the trait_wf test would not load without the fix). Still I added a general test in this PR, which is better for documentation.
| } else { | ||
| answer = actual_answer; | ||
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| let fixed_point = actual_answer == answer; |
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Can you add a comment here explaining why we have this special case? Also, I suspect that you can get into similar problems when you have guidance as well, no?
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I suspect it as well although ambig with guidance can perform some unification, but I cannot find examples where a cycle gives ambig with guidance after being fed. Nonetheless stopping when we get Ambig regardless of the guidance should not affect correctness of the final answer.
scalexm
changed the title
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This should solve the problem where an
Ambig(Unknown)answer was used to feed a cycle and not producing back any answer.