Workaround for scala/bug#8825

ThoughtWorksInc · Feb 28, 2018 · 5086819 · 5086819
1 parent 4161b44
commit 5086819
Showing 1 changed file with 29 additions and 4 deletions.
diff --git a/CompilerPlugin/src/main/scala/com/thoughtworks/dsl/CompilerPlugin.scala b/CompilerPlugin/src/main/scala/com/thoughtworks/dsl/CompilerPlugin.scala
@@ -109,6 +109,26 @@ final class CompilerPlugin(override val global: Global) extends Plugin {
       tree.productIterator.exists(hasCpsAttachment)
     }
 
+    /** Avoid [[UnApply]] in `patterTree` to suppress compiler crash due to `unexpected UnApply xxx`.
+      *
+      * @see https://github.com/scala/bug/issues/8825
+      */
+    private def scalaBug8825Workaround(patterTree: Tree): Tree = {
+      val transformer = new Transformer {
+        override def transform(tree: global.Tree): global.Tree = {
+          tree match {
+            case UnApply(
+                Apply(Select(prefix, termNames.unapply | termNames.unapplySeq), List(Ident(termNames.SELECTOR_DUMMY))),
+                args) =>
+              pq"$prefix(..${transformTrees(args)})"
+            case _ =>
+              super.transform(tree)
+          }
+        }
+      }
+      transformer.transform(patterTree)
+    }
+
     private val whileName = currentUnit.freshTermName("while")
     private val whileDef = {
       val domainName = currentUnit.freshTypeName("Domain")
@@ -251,7 +271,7 @@ final class CompilerPlugin(override val global: Global) extends Plugin {
                   selectorValue,
                   cases.map {
                     case caseDef @ CaseDef(pat, guard, body) =>
-                      treeCopy.CaseDef(caseDef, pat, guard, cpsAttachment(body) { bodyValue =>
+                      treeCopy.CaseDef(caseDef, scalaBug8825Workaround(pat), guard, cpsAttachment(body) { bodyValue =>
                         q"$endMatchName($bodyValue)"
                       })
                   }
@@ -283,9 +303,14 @@ final class CompilerPlugin(override val global: Global) extends Plugin {
               case ..${{
               catches.map { caseDef =>
                 atPos(caseDef.pos) {
-                  CaseDef(caseDef.pat, caseDef.guard, cpsAttachment(caseDef.body) { bodyValue =>
-                    q"$finalizerName(_root_.scala.util.Success($bodyValue))"
-                  })
+                  treeCopy.CaseDef(
+                    caseDef,
+                    scalaBug8825Workaround(caseDef.pat),
+                    caseDef.guard,
+                    cpsAttachment(caseDef.body) { bodyValue =>
+                      q"$finalizerName(_root_.scala.util.Success($bodyValue))"
+                    }
+                  )
                 }
               }
             }}