Unchecked overrides in quoted expressions unless expanded

[prolativ]

Compiler version

3.2.1-RC1-bin-20220717-5c43324-NIGHTLY and before

Minimized code

MacroOverride.scala:

//> using scala "3.2.1-RC1-bin-20220717-5c43324-NIGHTLY"

import scala.quoted.*

trait Foo:
  def xxx: Int

inline def foo(inline cond: Boolean) = ${ fooImpl('cond) }

def fooImpl(cond: Expr[Boolean])(using Quotes) =
  if cond.valueOrAbort then
    '{
      new Foo {
        override def xxx = 2
      }
    }
  else
    '{
      new Foo {
        override def xxxx = 1
      }
    }

MacroOverrideTest.scala:

val f = foo(true)

Output

No error

Expectation

The compiler should complain about the implementation of Foo in the else branch - it doesn't implement xxx and overrides xxxx, which doesn't exist in Foo. Currently one only gets the error if the quoted expression with the invalid implementation actually gets expanded, e.g. if one invokes foo(false)

[nicolasstucki]

These checks are done in the transformPhases of the compiler. But by then the contents of the quote are pickled. We would need to perform them before pickling.