1 files changed, 59 insertions, 0 deletions
diff --git a/core/shared/src/main/scala/globalutil.scala b/core/shared/src/main/scala/globalutil.scala
new file mode 100644
index 0000000..99dee77
--- /dev/null
+++ b/core/shared/src/main/scala/globalutil.scala
@@ -0,0 +1,59 @@
+package magnolia
+
+import scala.reflect.macros.{runtime, whitebox}
+import scala.tools.nsc.Global
+
+/** Workarounds that needs to use `nsc.Global`. */
+private[magnolia] object GlobalUtil {
+
+  // From Shapeless: https://github.com/milessabin/shapeless/blob/master/core/src/main/scala/shapeless/generic.scala#L698
+  // Cut-n-pasted (with most original comments) and slightly adapted from
+  // https://github.com/scalamacros/paradise/blob/c14c634923313dd03f4f483be3d7782a9b56de0e/plugin/src/main/scala/org/scalamacros/paradise/typechecker/Namers.scala#L568-L613
+  def patchedCompanionRef(c: whitebox.Context)(tpe: c.Type): c.Tree = {
+    // see https://github.com/scalamacros/paradise/issues/7
+    // also see https://github.com/scalamacros/paradise/issues/64
+
+    val global = c.universe.asInstanceOf[Global]
+    val typer = c.asInstanceOf[runtime.Context].callsiteTyper.asInstanceOf[global.analyzer.Typer]
+    val ctx = typer.context
+    val globalType = tpe.asInstanceOf[global.Type]
+    val original = globalType.typeSymbol
+    val owner = original.owner
+    val companion = original.companion.orElse {
+      import global.{ abort => aabort, _ }
+      implicit class PatchedContext(ctx: global.analyzer.Context) {
+        trait PatchedLookupResult { def suchThat(criterion: Symbol => Boolean): Symbol }
+        def patchedLookup(name: Name, expectedOwner: Symbol) = new PatchedLookupResult {
+          override def suchThat(criterion: Symbol => Boolean): Symbol = {
+            var res: Symbol = NoSymbol
+            var ctx = PatchedContext.this.ctx
+            while (res == NoSymbol && ctx.outer != ctx) {
+              // NOTE: original implementation says `val s = ctx.scope lookup name`
+              // but we can't use it, because Scope.lookup returns wrong results when the lookup is ambiguous
+              // and that triggers https://github.com/scalamacros/paradise/issues/64
+              val s = {
+                val lookupResult = ctx.scope.lookupAll(name).filter(criterion).toList
+                lookupResult match {
+                  case Nil => NoSymbol
+                  case List(unique) => unique
+                  case _ => aabort(s"unexpected multiple results for a companion symbol lookup for $original#{$original.id}")
+                }
+              }
+              if (s != NoSymbol && s.owner == expectedOwner)
+                res = s
+              else
+                ctx = ctx.outer
+            }
+            res
+          }
+        }
+      }
+
+      ctx.patchedLookup(original.name.companionName, owner) suchThat { sym =>
+        (original.isTerm || sym.hasModuleFlag) && (sym isCoDefinedWith original)
+      }
+    }
+
+    global.gen.mkAttributedRef(globalType.prefix, companion).asInstanceOf[c.Tree]
+  }
+}