Comments (4)
Since #56004 we reason more deeply (and correctly) about conditional type constraints, which definitely is a good thing. In this particular example it apparently causes us to materialize intersection types of the form ("foo" | Exclude<Q, "foo>) & ("bar | Exclude<Q, "bar">) & ....
with 18 or so union types being intersected. This comes out to 2^18 possible constituents, which is above our 100,000 limit. Of course, the final intersection will actually only have 19 constituents because all of the literal types intersect to never
. But we don't realize that.
Here's a simpler repro:
// Error: Expression produces a union type that is too complex to represent.
type Foo<T extends string> =
& ("a" | T)
& ("b" | T)
& ("c" | T)
& ("d" | T)
& ("e" | T)
& ("f" | T)
& ("g" | T)
& ("h" | T)
& ("i" | T)
& ("j" | T)
& ("k" | T)
& ("l" | T)
& ("m" | T)
& ("n" | T)
& ("q" | T)
& ("p" | T)
& ("q" | T)
& ("r" | T);
I'll think about ways to optimize this.
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I assume you mean "properties" instead of "parameters"? There are no function types in the Update
interface, let alone ones with large numbers of parameters.
from typescript.
Bisects to #56004
from typescript.
@ahejlsberg seems like Not a Defect to me but wanted to double-check
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