`inline val` for `opaque type` alias for literal type 'must have a literal constant type'

[armanbilge]

Compiler version

3.1.1-RC1

Minimized code

// This compiles:
opaque type One = 1
inline val One: One = 1

// But this does not:
opaque type Max = Int.MaxValue.type
inline val Max: Max = Int.MaxValue
// inline value must have a literal constant type

// However, this does:
inline val MaxValue: Int.MaxValue.type = Int.MaxValue

Output

[error] 33 |inline val Max: Max = Int.MaxValue
[error]    |                ^^^
[error]    |                inline value must have a literal constant type
[error] one error found

Expectation

If it is possible to inline a value of literal type Int.MaxValue, it should be possible to inline an opaque alias of that.

[nicolasstucki]

Actually inline val One: One = 1 should have been rejected because One is not generally known to be a constant value. It is only known in the scope where the opaque type is defined.

For example in this test we will not be able to inline it and will fail with a more confusing error message.

object Num {
  opaque type One = 1
  inline val One: One = 1
}

def test = Num.One
//         ^^^^^^^
//         getter One is declared as `inline`, but was not inlined
//
//         Try increasing `-Xmax-inlines` above 32