Nullability analysis kicks in without the compiler flag when working with macros

[anatoliykmetyuk]

Minimized code

macros.scala:

import scala.quoted._

type Foo
type F[X]
def varargsFunc(funcs0: Foo*) = ???

inline def mcr1: F[String] = ${ mcr1Impl }
def mcr1Impl(using QuoteContext): Expr[F[String]] = '{???}

inline def mcr2: Unit = ${mcr2Impl}
def mcr2Impl(using ctx: QuoteContext): Expr[Unit] =
  val func: Expr[Seq[Foo] => Unit] =
    '{ (esx: Seq[Foo]) => varargsFunc(esx: _*) }
  val trees: Expr[Seq[Foo]] =
    '{Nil}
  Expr.betaReduce(func)(trees)

Test.scala:

def f(x: => Any) = ???
def g = f {
  mcr1
  mcr2
}

Compile without any flags.

Output

-- Error: /Users/kmetiuk/Projects/scala3/playground/upickle-nullability/Test.scala:2:10
2 |def g = f {
  |          ^
  |This argument was typed using flow assumptions about mutable variables
  |but it is passed to a by-name parameter where such flow assumptions are unsound.
  |Wrapping the argument in `byName(...)` fixes the problem by disabling the flow assumptions.
  |
  |`byName` needs to be imported from the `scala.compiletime` package.
3 |  mcr1
4 |  mcr2
5 |}
1 error found

Expectation

The above is a nullability error. It should not appear since I am not compiling with -Yexplicit-nulls.