Redefine semantics of inline parameters

See docs/docs/reference/metaprogramming/inline.md

compiler/src/dotty/tools/dotc/core/TypeErasure.scala

@@ -533,7 +533,7 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
         // but potentially re-introduced by ResolveSuper, when we add
         // forwarders to mixin methods.
         // See doc comment for ElimByName for speculation how we could improve this.
-      else MethodType(Nil, Nil, eraseResult(sym.info.finalResultType))
+      else MethodType(Nil, Nil, eraseResult(sym.info.finalResultType.underlyingIfRepeated(isJava)))
     case tp: PolyType =>
       eraseResult(tp.resultType) match {
         case rt: MethodType => rt

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -3360,11 +3360,11 @@ object Types {
     /** Produce method type from parameter symbols, with special mappings for repeated
      *  and inline parameters:
      *   - replace @repeated annotations on Seq or Array types by <repeated> types
-     *   - add @inlineParam to inline call-by-value parameters
+     *   - add @inlineParam to inline parameters
      */
     def fromSymbols(params: List[Symbol], resultType: Type)(implicit ctx: Context): MethodType = {
       def translateInline(tp: Type): Type = tp match {
-        case _: ExprType => tp
+        case ExprType(resType) => ExprType(AnnotatedType(resType, Annotation(defn.InlineParamAnnot)))
         case _ => AnnotatedType(tp, Annotation(defn.InlineParamAnnot))
       }
       def paramInfo(param: Symbol) = {

compiler/src/dotty/tools/dotc/reporting/trace.scala

@@ -25,9 +25,18 @@ object trace extends TraceSyntax {
 abstract class TraceSyntax {
   val isForced: Boolean
 
+  // FIXME Use this signature after reference compiler is updated
+  // inline def onDebug[TD](inline question: String)(inline op: TD)(implicit ctx: Context): TD =
   inline def onDebug[TD](question: => String)(op: => TD)(implicit ctx: Context): TD =
     conditionally(ctx.settings.YdebugTrace.value, question, false)(op)
 
+  // FIXME Use this implementation after reference compiler is updated
+  // inline def conditionally[TC](inline cond: Boolean, inline question: String, inline show: Boolean)(op: => TC)(implicit ctx: Context): TC =
+  //   inline if (isForced || Config.tracingEnabled) {
+  //     if (cond) apply[TC](question, Printers.default, show)(op)
+  //     else op
+  //   }
+  //   else op
   inline def conditionally[TC](cond: Boolean, question: => String, show: Boolean)(op: => TC)(implicit ctx: Context): TC =
     inline if (isForced || Config.tracingEnabled) {
       def op1 = op
@@ -36,6 +45,13 @@ abstract class TraceSyntax {
     }
     else op
 
+  // FIXME Use this implementation after reference compiler is updated
+  // inline def apply[T](inline question: String, inline printer: Printers.Printer, inline showOp: Any => String)(op: => T)(implicit ctx: Context): T =
+  //   inline if (isForced || Config.tracingEnabled) {
+  //     if (!isForced && printer.eq(config.Printers.noPrinter)) op
+  //     else doTrace[T](question, printer, showOp)(op)
+  //   }
+  //   else op
   inline def apply[T](question: => String, printer: Printers.Printer, showOp: Any => String)(op: => T)(implicit ctx: Context): T =
     inline if (isForced || Config.tracingEnabled) {
       def op1 = op
@@ -44,6 +60,13 @@ abstract class TraceSyntax {
     }
     else op
 
+  // FIXME Use this implementation after reference compiler is updated
+  // inline def apply[T](inline question: String, inline printer: Printers.Printer, inline show: Boolean)(op: => T)(implicit ctx: Context): T =
+  //   inline if (isForced || Config.tracingEnabled) {
+  //     if (!isForced && printer.eq(config.Printers.noPrinter)) op
+  //     else doTrace[T](question, printer, if (show) showShowable(_) else alwaysToString)(op)
+  //   }
+  //   else op
   inline def apply[T](question: => String, printer: Printers.Printer, show: Boolean)(op: => T)(implicit ctx: Context): T =
     inline if (isForced || Config.tracingEnabled) {
       def op1 = op
@@ -52,12 +75,18 @@ abstract class TraceSyntax {
     }
     else op
 
+  // FIXME Use this signature after reference compiler is updated
+  // inline def apply[T](inline question: String, inline printer: Printers.Printer)(inline op: T)(implicit ctx: Context): T =
   inline def apply[T](question: => String, printer: Printers.Printer)(op: => T)(implicit ctx: Context): T =
     apply[T](question, printer, false)(op)
 
+  // FIXME Use this signature after reference compiler is updated
+  // inline def apply[T](inline question: String, inline show: Boolean)(inline op: T)(implicit ctx: Context): T =
   inline def apply[T](question: => String, show: Boolean)(op: => T)(implicit ctx: Context): T =
     apply[T](question, Printers.default, show)(op)
 
+  // FIXME Use this signature after reference compiler is updated
+  // inline def apply[T](inline question: String)(inline op: T)(implicit ctx: Context): T =
   inline def apply[T](question: => String)(op: => T)(implicit ctx: Context): T =
     apply[T](question, Printers.default, false)(op)
 

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

@@ -818,43 +818,8 @@ trait Checking {
     tree.tpe.widenTermRefExpr match {
       case tp: ConstantType if exprPurity(tree) >= purityLevel => // ok
       case _ =>
-        tree match {
-          case Typed(expr, _) =>
-            checkInlineConformant(expr, isFinal, what)
-          case Inlined(_, Nil, expr) =>
-            checkInlineConformant(expr, isFinal, what)
-          case SeqLiteral(elems, _) =>
-            elems.foreach(elem => checkInlineConformant(elem, isFinal, what))
-          case Apply(fn, List(arg)) if defn.WrapArrayMethods().contains(fn.symbol) =>
-            checkInlineConformant(arg, isFinal, what)
-          case _ =>
-            def isCaseClassApply(sym: Symbol): Boolean =
-              sym.name == nme.apply && sym.is(Synthetic) && sym.owner.is(Module) && sym.owner.companionClass.is(Case)
-            def isCaseClassNew(sym: Symbol): Boolean =
-              sym.isPrimaryConstructor && sym.owner.is(Case) && sym.owner.isStatic
-            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"$what must be a known value", tree.sourcePos)
-            else {
-              def checkArgs(tree: Tree): Unit = tree match {
-                case Apply(fn, args) =>
-                  args.foreach(arg => checkInlineConformant(arg, isFinal, what))
-                  checkArgs(fn)
-                case _ =>
-              }
-              checkArgs(tree)
-            }
-        }
+        if (!ctx.erasedTypes && !ctx.inInlineMethod)
+          ctx.error(em"$what must be a known value", tree.sourcePos)
     }
   }
 

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

@@ -223,7 +223,7 @@ object Inliner {
             res ++= typerErrors.map(e => ErrorKind.Typer -> e)
           res.toList
         case t =>
-          assert(ctx.reporter.hasErrors) // at least: argument to inline parameter must be a known value
+          ctx.error("expected argument to be a statically known String", codeArg.sourcePos)
           Nil
       }
 
@@ -333,9 +333,10 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
     val argtpe = arg.tpe.dealiasKeepAnnots
     val isByName = paramtp.dealias.isInstanceOf[ExprType]
     var inlineFlags: FlagSet = InlineProxy
-    if (paramtp.hasAnnotation(defn.InlineParamAnnot)) inlineFlags |= Inline
+    if (paramtp.widenExpr.hasAnnotation(defn.InlineParamAnnot)) inlineFlags |= Inline
+    if (isByName) inlineFlags |= Method
     val (bindingFlags, bindingType) =
-      if (isByName) (InlineByNameProxy.toTermFlags, ExprType(argtpe.widen))
+      if (isByName) (inlineFlags, ExprType(argtpe.widen))
       else (inlineFlags, argtpe.widen)
     val boundSym = newSym(name, bindingFlags, bindingType).asTerm
     val binding = {
@@ -765,10 +766,8 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
         def search(buf: mutable.ListBuffer[ValOrDefDef]) = buf.find(_.name == tree.name)
         if (paramProxies.contains(tree.typeOpt))
           search(bindingsBuf) match {
-            case Some(vdef: ValDef) if vdef.symbol.is(Inline) =>
-              Some(integrate(vdef.rhs, vdef.symbol))
-            case Some(ddef: DefDef) =>
-              Some(integrate(ddef.rhs, ddef.symbol))
+            case Some(bind: ValOrDefDef) if bind.symbol.is(Inline) =>
+              Some(integrate(bind.rhs, bind.symbol))
             case _ => None
           }
         else None
@@ -1198,7 +1197,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
       val bindingOfSym = newMutableSymbolMap[MemberDef]
 
       def isInlineable(binding: MemberDef) = binding match {
-        case DefDef(_, Nil, Nil, _, _) => true
+        case ddef @ DefDef(_, Nil, Nil, _, _) => isPureExpr(ddef.rhs)
         case vdef @ ValDef(_, _, _) => isPureExpr(vdef.rhs)
         case _ => false
       }
@@ -1236,7 +1235,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
           case Some(x) => x > 1 || x == 1 && !boundSym.is(Method)
           case none => true
         }
-      } && !(boundSym.isAllOf(InlineMethod) && boundSym.isOneOf(GivenOrImplicit))
+      } && !boundSym.is(Inline)
 
       val inlineBindings = new TreeMap {
         override def transform(t: Tree)(implicit ctx: Context) = t match {

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

@@ -2910,8 +2910,6 @@ class Typer extends Namer
           tree
         }
       else if (tree.tpe.widenExpr <:< pt) {
-        if (pt.hasAnnotation(defn.InlineParamAnnot))
-          checkInlineConformant(tree, isFinal = false, "argument to inline parameter")
         if (ctx.typeComparer.GADTused && pt.isValueType)
           // Insert an explicit cast, so that -Ycheck in later phases succeeds.
           // I suspect, but am not 100% sure that this might affect inferred types,

compiler/src/dotty/tools/dotc/util/Stats.scala

@@ -19,6 +19,8 @@ import collection.mutable
     override def default(key: String): Int = 0
   }
 
+  // FIXME Use this signature after reference compiler is updated
+  // inline def record(inline fn: String, inline n: Int = 1): Unit =
   inline def record(fn: => String, n: => Int = 1): Unit =
     if (enabled) doRecord(fn, n)
 
@@ -28,16 +30,17 @@ import collection.mutable
       hits(name) += n
     }
 
+  // FIXME Use this signature after reference compiler is updated
+  // inline def trackTime[T](fn: String)(inline op: T): T =
   inline def trackTime[T](fn: String)(op: => T): T =
     if (enabled) doTrackTime(fn)(op) else op
 
   def doTrackTime[T](fn: String)(op: => T): T = {
-    def op1 = op
     if (monitored) {
       val start = System.nanoTime
-      try op1 finally record(fn, ((System.nanoTime - start) / 1000).toInt)
+      try op finally record(fn, ((System.nanoTime - start) / 1000).toInt)
     }
-    else op1
+    else op
   }
 
   final val GroupChar = '/'