From 1d4db7fd65a1376ce71086a1a7fc5c524ee3a233 Mon Sep 17 00:00:00 2001
From: Som Snytt <som.snytt@gmail.com>
Date: Fri, 11 Oct 2024 16:23:06 -0700
Subject: [PATCH] Regression tests

---
 tests/pos/i17631.scala  | 14 ++++++++++++++
 tests/pos/i18366.scala  | 15 ++++++++++++---
 tests/warn/i17371.scala | 28 ++++++++++++++++++++++++++++
 tests/warn/i18313.scala | 14 ++++++++++++++
 4 files changed, 68 insertions(+), 3 deletions(-)
 create mode 100644 tests/warn/i17371.scala
 create mode 100644 tests/warn/i18313.scala

diff --git a/tests/pos/i17631.scala b/tests/pos/i17631.scala
index 0ede23dd5524..ddcb71354968 100644
--- a/tests/pos/i17631.scala
+++ b/tests/pos/i17631.scala
@@ -38,3 +38,17 @@ def `i18388`: Unit =
     val _ = pred
     ()
   val _ = func
+
+trait L[T]:
+  type E
+
+def `i19748` =
+  type Warn1 = [T] => (l: L[T]) => T => l.E
+  type Warn2 = [T] => L[T] => T
+  type Warn3 = [T] => T => T
+  def use(x: (Warn1, Warn2, Warn3)) = x
+  use
+
+type NoWarning1 = [T] => (l: L[T]) => T => l.E
+type NoWarning2 = [T] => L[T] => T
+type NoWarning3 = [T] => T => T
diff --git a/tests/pos/i18366.scala b/tests/pos/i18366.scala
index 698510ad13a2..b6385b5bbb59 100644
--- a/tests/pos/i18366.scala
+++ b/tests/pos/i18366.scala
@@ -1,10 +1,19 @@
-//> using options -Xfatal-warnings -Wunused:all
+//> using options -Werror -Wunused:all
 
 trait Builder {
   def foo(): Unit
 }
 
-def repro =
+def `i18366` =
   val builder: Builder = ???
   import builder.{foo => bar}
-  bar()
\ No newline at end of file
+  bar()
+
+import java.io.DataOutputStream
+
+val buffer: DataOutputStream = ???
+
+import buffer.{write => put}
+
+def `i17315` =
+  put(0: Byte)
diff --git a/tests/warn/i17371.scala b/tests/warn/i17371.scala
new file mode 100644
index 000000000000..9e1c26368b8f
--- /dev/null
+++ b/tests/warn/i17371.scala
@@ -0,0 +1,28 @@
+//> using options -Wunused:all
+
+class A
+class B
+
+def Test() =
+  val ordA: Ordering[A] = ???
+  val ordB: Ordering[B] = ???
+  val a: A = ???
+  val b: B = ???
+
+  import ordA.given
+  val _ = a > a
+  
+  import ordB.given
+  val _ = b < b
+
+// unminimized OP
+trait Circular[T] extends Ordering[T]
+trait Turns[C: Circular, T] extends Ordering[T]:
+  extension (turns: T) def extract: C
+
+def f[K, T](start: T, end: T)(using circular: Circular[K], turns: Turns[K, T]): Boolean =
+  import turns.given
+  if start > end then throw new IllegalArgumentException("start must be <= end")
+
+  import circular.given
+  start.extract < end.extract
diff --git a/tests/warn/i18313.scala b/tests/warn/i18313.scala
new file mode 100644
index 000000000000..967985853fcf
--- /dev/null
+++ b/tests/warn/i18313.scala
@@ -0,0 +1,14 @@
+//> using options -Wunused:imports
+
+import scala.deriving.Mirror
+
+case class Test(i: Int, d: Double)
+case class Decoder(d: Product => Test)
+
+// OK, no warning returned
+//val ok = Decoder(summon[Mirror.Of[Test]].fromProduct)
+//
+// returns warning:
+// [warn] unused import
+// [warn] import scala.deriving.Mirror
+val d = Decoder(d = summon[Mirror.Of[Test]].fromProduct) // no warn