diff options
Diffstat (limited to 'compiler/src/dotty/tools/dotc/transform/FirstTransform.scala')
| -rw-r--r-- | compiler/src/dotty/tools/dotc/transform/FirstTransform.scala | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/compiler/src/dotty/tools/dotc/transform/FirstTransform.scala b/compiler/src/dotty/tools/dotc/transform/FirstTransform.scala index 597146514..9e71fda5d 100644 --- a/compiler/src/dotty/tools/dotc/transform/FirstTransform.scala +++ b/compiler/src/dotty/tools/dotc/transform/FirstTransform.scala @@ -31,6 +31,9 @@ import StdNames._ * - eliminates self tree in Template and self symbol in ClassInfo * - collapsess all type trees to trees of class TypeTree * - converts idempotent expressions with constant types + * - drops branches of ifs using the rules + * if (true) A else B --> A + * if (false) A else B --> B */ class FirstTransform extends MiniPhaseTransform with InfoTransformer with AnnotationTransformer { thisTransformer => import ast.tpd._ @@ -187,6 +190,12 @@ class FirstTransform extends MiniPhaseTransform with InfoTransformer with Annota override def transformBlock(tree: Block)(implicit ctx: Context, info: TransformerInfo) = constToLiteral(tree) + override def transformIf(tree: If)(implicit ctx: Context, info: TransformerInfo) = + tree.cond match { + case Literal(Constant(c: Boolean)) => if (c) tree.thenp else tree.elsep + case _ => tree + } + // invariants: all modules have companion objects // all types are TypeTrees // all this types are explicit |