Compare shapes of objects before comparing contained types#18126
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sandersn
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Aug 31, 2017
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It would be nice to know how much this helps performance, but the change is worth it for the improvement in error messages alone.
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With this PR, when comparing two object types we first check that the source type contains all properties required by the target type. Only when that is the case do we then proceed to compare the types of the properties. Previously we'd do both of these things in the same pass which could cause us to needlessly drill into the (possibly deep) types of matching properties only to later discover that other properties are missing (meaning that the types are not related).
As can be seen from the baseline differences, we now bail out quicker when types are not related. This reduces noise in error messages and should also help performance.