Fixed Missing warning for invalid recursive val

[gagandeepkalra]

resolves #14429

cc. @anatoliykmetyuk

[griggt]

Also #12943 which already seems to be fixed.

[mbovel]

Is | Lazy still needed? Aren't all lazy values ValDefs?

[mbovel]

About the error message:

• Infinite loop in function body does not seem appropriate for vals.
• Why don't we refer to the precise place where the recursion happens instead of embedding the function/val body in the error message?

Currently:

-- Warning: tests/neg-custom-args/fatal-warnings/i13011.scala:15:29 ------------
15 |  lazy val simple6: String = {  // error
   |                             ^
   |                             Infinite loop in function body
   |                             {
   |                               this.simple6
   |                               "aa"
   |                             }
16 |    this.simple6
17 |    "aa"
18 |  }

Instead, I would suggest:

-- Warning: tests/neg-custom-args/fatal-warnings/i13011.scala:16:9 -------------
16 |    this.simple6
   |    ^^^^^^^^^^^^
   |    Infinite loop

That could be achieved by simplifying checkNotSelfRef to:

def checkNotSelfRef(t: RefTree) =
  if t.symbol eq sym then
    report.warning("Infinite loop", t.srcPos)

Seems to work for for extension methods and givens as well:

-- Warning: tests/neg-custom-args/fatal-warnings/i13011.scala:22:41 ------------
22 |  extension (n: Int) def foo(): Unit = n.foo()
   |                                         ^^^
   |                                         Infinite loop
-- Warning: tests/neg-custom-args/fatal-warnings/i13011.scala:24:17 ------------
24 |  given x: Int = x
   |                 ^
   |                 Infinite loop

[mbovel]

Minor: should we rename this phase to CheckInfiniteLoops as it's not just about implicits?

[mbovel]

@gagandeepkalra do you plan to further work on this PR? It would be great to have it merged! 😃

[gagandeepkalra]

Hi @mbovel, I'll get back to working this.

[ckipp01]

Hi @mbovel, I'll get back to working this.

Hey @gagandeepkalra do you still plan on returning to this?

[som-snytt]

Closing in favor of Wsafe-init and/or -Ysafe-init-global, see the ticket.