Allow infix enum

Fixes #18933
scala · Nov 21, 2023 · 5f4f7c6 · 5f4f7c6
1 parent 8f37647
commit 5f4f7c6
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Showing 4 changed files with 20 additions and 1 deletion.
diff --git a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -3919,7 +3919,9 @@ object Parsers {
     }
 
     private def checkAccessOnly(mods: Modifiers, where: String): Modifiers =
-      val mods1 = mods & (AccessFlags | Enum)
+      // We allow `infix to mark the `enum`s type as infix.
+      // Syntax rules disallow the soft infix modifier on `case`s.
+      val mods1 = mods & (AccessFlags | Enum | Infix)
       if mods1 ne mods then
         syntaxError(em"Only access modifiers are allowed on enum $where")
       mods1

diff --git a/tests/neg/i18933.check b/tests/neg/i18933.check
@@ -0,0 +1,10 @@
+-- Error: tests/neg/i18933.scala:3:8 -----------------------------------------------------------------------------------
+3 |  infix case B(b: B) // error // error
+  |        ^^^^
+  |        end of statement expected but 'case' found
+-- [E006] Not Found Error: tests/neg/i18933.scala:3:2 ------------------------------------------------------------------
+3 |  infix case B(b: B) // error // error
+  |  ^^^^^
+  |  Not found: infix
+  |
+  | longer explanation available when compiling with `-explain`
diff --git a/tests/neg/i18933.scala b/tests/neg/i18933.scala
@@ -0,0 +1,3 @@
+enum Extends[A, B]:
+  case A(a: A)
+  infix case B(b: B) // error // error
diff --git a/tests/pos/i18933.scala b/tests/pos/i18933.scala
@@ -0,0 +1,4 @@
+//> using options -Werror
+
+infix enum Extends[A, B]:
+  case Ev[B, A <: B]() extends (A Extends B)