Disallow transparent inline given .. with ..

Author: nicolasstucki

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -809,7 +809,9 @@ object desugar {
             Nil
         }
       }
-      val classMods = if mods.is(Given) then mods &~ Inline | Synthetic else mods
+      if mods.isAllOf(Given | Inline | Transparent) then
+        report.error("inline non-alias given cannot be trasparent", cdef)
+      val classMods = if mods.is(Given) then mods &~ (Inline | Transparent) | Synthetic else mods
       cpy.TypeDef(cdef: TypeDef)(
         name = className,
         rhs = cpy.Template(impl)(constr, parents1, clsDerived, self1,

tests/neg/i14177c.scala

@@ -0,0 +1,15 @@
+class T
+
+transparent inline given fail1: T with // error
+  val cs = scala.compiletime.summonAll[EmptyTuple]
+transparent inline given fail2[X]: T with // error
+  val cs = scala.compiletime.summonAll[EmptyTuple]
+transparent inline given fail3(using DummyImplicit): T with // error
+  val cs = scala.compiletime.summonAll[EmptyTuple]
+
+transparent inline given ok1: T = new T:
+  val cs = scala.compiletime.summonAll[EmptyTuple]
+transparent inline given ok2[X]: T = new T:
+  val cs = scala.compiletime.summonAll[EmptyTuple]
+transparent inline given ok3(using DummyImplicit): T = new T:
+  val cs = scala.compiletime.summonAll[EmptyTuple]