Cache unnormalized intersection types #31476
Merged
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When creating intersection types we first normalize combinations of intersection and union types to place union types topmost. For example, this process turns
X & (A | B)
into the equivalentX & A | X & B
. The normalization process can be very costly for intersections involving large union types. With this PR we cache both unnormalized and normalized intersection types, where previously we would only cache the latter. This means that for a particular set of unnormalized input types, we will only perform the potentially expensive normalization process once.The improved caching lowers the check times for
react
andstyled-components
by ~25% and makes our performance better than 3.3: