Deprecation is emitted for inferred types

[som-snytt]

Compiler version

3.3.1

Minimized code

import scala.annotation.nowarn

@deprecated("is deprecated", "n/a")
class Thing(val value: Int)

object Main extends App {

  @nowarn("msg=is deprecated")
  def doo(): Option[Thing] = Some(new Thing(1))
  def wop(x: => Option[Thing]) = println(x)

  doo().map(t => println(t))
  doo().map((t: Thing) => println(t))
  doo().map(println)
  doo().foreach(println)
  for (x <- doo()) println(x)

  val thing = new Thing(42)
  println(thing)

  val something = Some(thing)
  wop(something)
}

Output

$ scalac -deprecation warns-too-much.scala
-- Deprecation Warning: warns-too-much.scala:12:23 ---------------------------------------------------------------------
12 |  def wop(x: => Option[Thing]) = println(x)
   |                       ^^^^^
   |                       class Thing is deprecated since n/a: is deprecated
-- Deprecation Warning: warns-too-much.scala:14:13 ---------------------------------------------------------------------
14 |  doo().map(t => println(t))
   |             ^
   |             class Thing is deprecated since n/a: is deprecated
-- Deprecation Warning: warns-too-much.scala:15:16 ---------------------------------------------------------------------
15 |  doo().map((t: Thing) => println(t))
   |                ^^^^^
   |                class Thing is deprecated since n/a: is deprecated
-- Deprecation Warning: warns-too-much.scala:18:8 ----------------------------------------------------------------------
18 |  for (x <- doo()) println(x)
   |        ^
   |        class Thing is deprecated since n/a: is deprecated
-- Deprecation Warning: warns-too-much.scala:20:11 ---------------------------------------------------------------------
20 |  val thing = new Thing(42)
   |           ^
   |           class Thing is deprecated since n/a: is deprecated
-- Deprecation Warning: warns-too-much.scala:20:18 ---------------------------------------------------------------------
20 |  val thing = new Thing(42)
   |                  ^^^^^
   |                  class Thing is deprecated since n/a: is deprecated
-- Deprecation Warning: warns-too-much.scala:23:15 ---------------------------------------------------------------------
23 |  val something = Some(thing)
   |               ^
   |               class Thing is deprecated since n/a: is deprecated
-- Deprecation Warning: warns-too-much.scala:23:18 ---------------------------------------------------------------------
23 |  val something = Some(thing)
   |                  ^^^^
   |                  class Thing is deprecated since n/a: is deprecated
8 warnings found

Expectation

$ scalac -Xlint warns-too-much.scala
warns-too-much.scala:12: warning: class Thing is deprecated (since n/a): is deprecated
  def wop(x: => Option[Thing]) = println(x)
             ^
warns-too-much.scala:15: warning: class Thing is deprecated (since n/a): is deprecated
  doo().map((t: Thing) => println(t))
                ^
warns-too-much.scala:20: warning: class Thing is deprecated (since n/a): is deprecated
  val thing = new Thing(42)
                  ^
3 warnings

Compare f, which does not warn:

➜  cat jdep.java
import java.util.Optional;

@Deprecated
class jdep {
}

class client {
        jdep g() {
                return new jdep();
        }
        void f() {
                var x = g();
                System.out.println(x);
                var y = Optional.of(g());
                System.out.println(y);
        }
}
➜  javac -Xlint:deprecation jdep.java
jdep.java:9: warning: [deprecation] jdep in unnamed package has been deprecated
        jdep g() {
        ^
jdep.java:10: warning: [deprecation] jdep in unnamed package has been deprecated
                return new jdep();
                           ^
2 warnings

Asked at https://discord.com/channels/632150470000902164/632150470000902166/1186776168020582400