Go handles dead code by not allowing you to compile something with dead code. In the examples the "_ =" is needed to force it to compile and do the work without actually assigning the value to anything.
x := true
var y = 0
if x {
y = 10
} else {
y = 20
}
So the question might be: what kind of dead code elimination exist in the compiler, apart from what you describe which has existed since the beginning of Go? (if I understand correctly)
This is obviously not true and is easily disproved.
Here's a program that compiles but has statically provably dead code on line 15 https://play.golang.org/p/_XcxezHV-6.
But even if I couldn't give you an example like that where the dead code is obvious, dead code is produced by the compiler itself as it optimises, and by code generation tools.
`_` mainly exists to allow ignoring single values, within multiple. Eg, dropping an error: `val, _ := MightError()`
_ serves multiple purposes, not just for ignoring a return value. It's often used when you care about the side effect but not the return value, such as importation a driver for a database . You'll never use the library, so you import it as _ "db.driver.name/path/".