Conversion of slice to array pointer

Question

As mentioned in Spec, Converting a slice to an array pointer yields a pointer to the underlying array of the slice.

s := make([]byte, 2, 4)
s0 := (*[0]byte)(s)      // s0 != nil

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But compiler gives error: cannot convert s (variable of type []byte) to *[0]byte

Answer 1

This conversion was added to the language in Go 1.17.

Changes to the language

Go 1.17 includes three small enhancements to the language.

• Conversions from slice to array pointer: An expression s of type []T may now be converted to array pointer type *[N]T. If a is the result of such a conversion, then corresponding indices that are in range refer to the same underlying elements: &a[i] == &s[i] for 0 <= i < N. The conversion panics if len(s) is less than N.
• [...]

This means you need Go 1.17 or newer to use such conversion. It works well on the Go Playground (currently the playground uses the latest Go 1.19).