How to create a vector of integers with structure()?

I don't seem to be able to produce a vector of integers using structure().

> x <- structure(c(1,2), class='integer', mode='integer', storage.mode='integer')
 > paste(class(x), mode(x), storage.mode(x), is.integer(x))
 [1] "integer numeric double FALSE"
 

Compare with a true vector of integers:

> y <- as.integer(c(1,2))
 > paste(class(y), mode(y), storage.mode(y), is.integer(y))
 [1] "integer numeric integer TRUE"
 

Any idea?

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