Does Go guarantee constant addresses?

Question

Given an object obj is there a guarantee that

uintptr(unsafe.Pointer(&obj))

will always evaluate to the same value regardless of w

Answer 1

No absolute guarantee. Especially if Go adds compaction to its mark and sweep garbage collector.

Addresses stored in pointer types and type unsafe.Pointer will be updated, if necessary, by any garbage collector. Addresses stored in type uintptr as unsigned integers will not be updated by a garbage collector. The uintptr type is not a pointer type, it's an integer type.

Numeric types

uintptr an unsigned integer large enough to store the uninterpreted bits of a pointer value

converting unsafe.Pointers to uintptr

Pointers should have been kept in unsafe.Pointers - not uintptrs - always.

Russ

For your example,

uintptr(unsafe.Pointer(&obj))

you have an unsigned integer, not an address.