Constant fold on StringInterpolatorOpt

Author: nicolasstucki

compiler/src/dotty/tools/dotc/transform/localopt/StringInterpolatorOpt.scala

@@ -11,6 +11,7 @@ import dotty.tools.dotc.core.NameKinds._
 import dotty.tools.dotc.core.Symbols._
 import dotty.tools.dotc.core.Types._
 import dotty.tools.dotc.transform.MegaPhase.MiniPhase
+import dotty.tools.dotc.typer.ConstFold
 
 /**
   * MiniPhase to transform s and raw string interpolators from using StringContext to string
@@ -162,6 +163,18 @@ class StringInterpolatorOpt extends MiniPhase {
           }
       }
     else
-      tree
+      tree.tpe match
+        case _: ConstantType => tree
+        case _ =>
+          ConstFold.Apply(tree).tpe match
+            case ConstantType(x) => Literal(x).withSpan(tree.span).ensureConforms(tree.tpe)
+            case _ => tree
   }
+
+  override def transformSelect(tree: Select)(using Context): Tree = {
+    ConstFold.Select(tree).tpe match
+      case ConstantType(x) => Literal(x).withSpan(tree.span).ensureConforms(tree.tpe)
+      case _ => tree
+  }
+
 }

tests/run-macros/tasty-extractors-1.check

@@ -73,8 +73,8 @@ ConstantType(IntConstant(2))
 Inlined(None, Nil, Try(Literal(IntConstant(3)), List(CaseDef(Ident("_"), None, Block(Nil, Literal(UnitConstant())))), Some(Literal(UnitConstant()))))
 OrType(ConstantType(IntConstant(3)), TypeRef(ThisType(TypeRef(NoPrefix(), "scala")), "Unit"))
 
-Inlined(None, Nil, Apply(Select(Literal(StringConstant("a")), "=="), List(Literal(StringConstant("b")))))
-TypeRef(ThisType(TypeRef(NoPrefix(), "scala")), "Boolean")
+Inlined(None, Nil, Literal(BooleanConstant(false)))
+ConstantType(BooleanConstant(false))
 
 Inlined(None, Nil, Apply(Select(New(TypeIdent("Object")), "<init>"), Nil))
 TypeRef(ThisType(TypeRef(NoPrefix(), "lang")), "Object")