Merge pull request #7979 from dotty-staging/fix-#7964

Fix #7964: Allow inline enum parameters

Author: nicolasstucki

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

@@ -2,7 +2,7 @@ package dotty.tools.dotc
 package transform
 
 import java.io.{PrintWriter, StringWriter}
-import java.lang.reflect.{InvocationTargetException, Method}
+import java.lang.reflect.{InvocationTargetException, Method => JLRMethod}
 
 import dotty.tools.dotc.ast.tpd
 import dotty.tools.dotc.ast.Trees._
@@ -194,10 +194,13 @@ object Splicer {
           interpretNew(fn.symbol, args.flatten.map(interpretTree))
         else if (fn.symbol.is(Module))
           interpretModuleAccess(fn.symbol)
-        else if (fn.symbol.isStatic) {
+        else if (fn.symbol.is(Method) && fn.symbol.isStatic) {
           val staticMethodCall = interpretedStaticMethodCall(fn.symbol.owner, fn.symbol)
           staticMethodCall(args.flatten.map(interpretTree))
         }
+        else if (fn.symbol.isStatic)
+          assert(args.isEmpty)
+          interpretedStaticFieldAccess(fn.symbol)
         else if (fn.qualifier.symbol.is(Module) && fn.qualifier.symbol.isStatic)
           if (fn.name == nme.asInstanceOfPM)
             interpretModuleAccess(fn.qualifier.symbol)
@@ -277,6 +280,12 @@ object Splicer {
       (args: List[Object]) => stopIfRuntimeException(method.invoke(inst, args: _*), method)
     }
 
+    private def interpretedStaticFieldAccess(sym: Symbol)(implicit env: Env): Object = {
+      val clazz = loadClass(sym.owner.fullName.toString)
+      val field = clazz.getField(sym.name.toString)
+      field.get(null)
+    }
+
     private def interpretModuleAccess(fn: Symbol)(implicit env: Env): Object =
       loadModule(fn.moduleClass)
 
@@ -319,15 +328,15 @@ object Splicer {
           throw new StopInterpretation(msg, pos)
       }
 
-    private def getMethod(clazz: Class[?], name: Name, paramClasses: List[Class[?]]): Method =
+    private def getMethod(clazz: Class[?], name: Name, paramClasses: List[Class[?]]): JLRMethod =
       try clazz.getMethod(name.toString, paramClasses: _*)
       catch {
         case _: NoSuchMethodException =>
           val msg = em"Could not find method ${clazz.getCanonicalName}.$name with parameters ($paramClasses%, %)"
           throw new StopInterpretation(msg, pos)
       }
 
-    private def stopIfRuntimeException[T](thunk: => T, method: Method): T =
+    private def stopIfRuntimeException[T](thunk: => T, method: JLRMethod): T =
       try thunk
       catch {
         case ex: RuntimeException =>

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

@@ -835,10 +835,13 @@ trait Checking {
             def isCaseObject(sym: Symbol): Boolean =
               // TODO add alias to Nil in scala package
               sym.is(Case) && sym.is(Module)
+            def isStaticEnumCase(sym: Symbol): Boolean =
+              sym.is(Enum) && sym.is(JavaStatic) && sym.is(Case)
             val allow =
               ctx.erasedTypes ||
               ctx.inInlineMethod ||
               (tree.symbol.isStatic && isCaseObject(tree.symbol) || isCaseClassApply(tree.symbol)) ||
+              isStaticEnumCase(tree.symbol) ||
               isCaseClassNew(tree.symbol)
 
             if (!allow) ctx.error(em"$what must be a known value", tree.sourcePos)

tests/pos/i7964.scala

@@ -0,0 +1,9 @@
+enum Nums { case One; case Two }
+
+def fok(that: Nums) = ???
+val ok = fok(Nums.One)
+
+inline def fko(inline that: Nums) = inline that match {
+  case Nums.One => "fff(one)"
+}
+val ko = fko(Nums.One)

tests/run-macros/i7964/Macro_1.scala

@@ -0,0 +1,15 @@
+import scala.quoted._
+
+enum Num {
+  case One
+  case Two
+}
+
+inline def foo(inline num: Num): Int = ${ fooExpr(num) }
+
+private def fooExpr(num: Num)(given QuoteContext): Expr[Int] = Expr(toInt(num))
+
+private def toInt(num: Num): Int = num match {
+  case Num.One => 1
+  case Num.Two => 2
+}

tests/run-macros/i7964/Test_2.scala

@@ -0,0 +1,4 @@
+object Test extends App {
+  assert(foo(Num.One) == 1)
+  assert(foo(Num.Two) == 2)
+}