Fix #4574: Don't generate inline accessor for constants

Author: allanrenucci

compiler/src/dotty/tools/dotc/transform/PostTyper.scala

@@ -17,7 +17,7 @@ object PostTyper {
 
 /** A macro transform that runs immediately after typer and that performs the following functions:
  *
- *  (1) Add super accessors and protected accessors (@see SuperAccessors)
+ *  (1) Add super accessors (@see SuperAccessors)
  *
  *  (2) Convert parameter fields that have the same name as a corresponding
  *      public parameter field in a superclass to a forwarder to the superclass

compiler/src/dotty/tools/dotc/typer/Inliner.scala

@@ -53,6 +53,7 @@ object Inliner {
         */
       def needsAccessor(sym: Symbol)(implicit ctx: Context) =
         sym.isTerm &&
+        !sym.info.widenTermRefExpr.isInstanceOf[ConstantType] &&
         (sym.is(AccessFlags) || sym.privateWithin.exists) &&
         !sym.isContainedIn(inlineSym)
 

tests/pos/i4754.scala

@@ -0,0 +1,12 @@
+object Foo {
+  private final val C = "Constant"
+}
+
+class Foo {
+  import Foo._
+  inline def foo(x: Int): Boolean = x == C.length
+}
+
+class Test {
+  (new Foo).foo(1)
+}