Merge pull request #12137 from dotty-staging/fix-12073

Handle alternative patterns in inline reduction

Author: nicolasstucki

compiler/src/dotty/tools/dotc/typer/Inliner.scala

@@ -1249,6 +1249,8 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(using Context) {
               case _ =>
                 false
             }
+          case Alternative(pats) =>
+            pats.exists(reducePattern(caseBindingMap, scrut, _))
           case Inlined(EmptyTree, Nil, ipat) =>
             reducePattern(caseBindingMap, scrut, ipat)
           case _ => false

tests/pos/i12073.scala

@@ -0,0 +1,70 @@
+inline def ff: Unit =
+  inline 1 match
+    case 1 | 2 =>
+
+def test = ff
+
+transparent inline def f: Option[String] =
+  None
+
+object Override {
+
+  trait Trait { def s: String }
+
+  object OK extends Trait {
+    override transparent inline def s: String =
+      inline f match {
+        case Some("x") => "x"
+        case Some("y") => "y"
+        case None      => "-"
+      }
+  }
+
+  object KO_1 extends Trait {
+    override transparent inline def s: String =
+      inline f match {
+        case Some("x") => "x"
+        case Some("y")
+           | None      => "0"
+      }
+  }
+
+  object KO_2 extends Trait {
+    override transparent inline def s: String =
+      inline f match {
+        case Some("x") => "x"
+        case Some("y") => "y"
+        case Some(z)   => "z"
+        case None      => "0"
+      }
+  }
+}
+
+object NonOverride {
+
+  transparent inline def ok_1: String =
+    inline f match {
+      case Some("x") => "x"
+      case Some("y") => "y"
+      case None      => "-"
+    }
+
+  // ok: Some("y") | None
+  transparent inline def ok_2: String =
+    inline f match {
+      case Some("x") => "x"
+      case Some("y")
+         | None      => "0"
+    }
+
+  // ok: no None
+  transparent inline def ok_3: String =
+    inline f match {
+      case Some("x") => "x"
+      case Some("y") => "y"
+      case Some(z)   => "z"
+      case None      => "0"
+    }
+
+  ok_1 + ok_2 ++ ok_3
+}