fix: Fix parsing error and a crash with non-reference-trait base type #4956
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This PR fixes three bugs.
One bug was that the new resolver didn't check that the base type of a subset type was determined.
Another bug was that, even after reporting the error in the first bug, the resolver could crash downstream.
The third bug was that, even with a properly formed
x: BaseType
, the verifier would crash when trying to construct a default witness (if the base type is a non-reference trait and there is no explicitwitness
clause).Fixes #4946
Note: I previously (and erroneously) thought the bug was a problem in the parser. But we do allow the syntax with just one identifier before the
|
in a subset-type declaration. The problem was that the new resolver didn't check to see that the type of that identifier was properly inferred.By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.