diff options
| -rw-r--r-- | src/compiler/scala/tools/nsc/transform/TailCalls.scala | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/src/compiler/scala/tools/nsc/transform/TailCalls.scala b/src/compiler/scala/tools/nsc/transform/TailCalls.scala index 868ee4489d..49bca5364c 100644 --- a/src/compiler/scala/tools/nsc/transform/TailCalls.scala +++ b/src/compiler/scala/tools/nsc/transform/TailCalls.scala @@ -320,8 +320,13 @@ abstract class TailCalls extends Transform { // the assumption is once we encounter a case, the remainder of the block will consist of cases // the prologue may be empty, usually it is the valdef that stores the scrut val (prologue, cases) = stats span (s => !s.isInstanceOf[LabelDef]) + val transformedPrologue = noTailTransforms(prologue) + val transformedCases = transformTrees(cases) + val transformedStats = + if ((prologue eq transformedPrologue) && (cases eq transformedCases)) stats // allow reuse of `tree` if the subtransform was an identity + else transformedPrologue ++ transformedCases treeCopy.Block(tree, - noTailTransforms(prologue) ++ transformTrees(cases), + transformedStats, transform(expr) ) |