Move all logic handling splices into splice

THis is possible now that we have access to information
about the outer inlined tree nodes via enclosingInlineds.
In particular we can recover the position where the macro was inlined.

Author: nicolasstucki

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

@@ -3,7 +3,6 @@ package transform
 
 import core._
 import Decorators._, Flags._, Types._, Contexts._, Symbols._, Constants._
-import Flags._
 import ast.Trees._
 import ast.{TreeTypeMap, untpd}
 import util.Positions._
@@ -16,6 +15,7 @@ import typer.Implicits.SearchFailureType
 import scala.collection.mutable
 import dotty.tools.dotc.core.StdNames._
 import dotty.tools.dotc.core.quoted._
+import dotty.tools.dotc.util.SourcePosition
 
 
 /** Translates quoted terms and types to `unpickle` method calls.
@@ -230,10 +230,6 @@ class ReifyQuotes extends MacroTransformWithImplicits {
         !sym.is(Param) || levelOK(sym.owner)
     }
 
-    /** Issue a "splice outside quote" error unless we are in the body of a transparent method */
-    def spliceOutsideQuotes(pos: Position)(implicit ctx: Context): Unit =
-      ctx.error(i"splice outside quotes", pos)
-
     /** Try to heal phase-inconsistent reference to type `T` using a local type definition.
      *  @return None      if successful
      *  @return Some(msg) if unsuccessful where `msg` is a potentially empty error message
@@ -292,7 +288,7 @@ class ReifyQuotes extends MacroTransformWithImplicits {
               outer.checkType(pos).foldOver(acc, tp)
             }
             else {
-              if (tp.isTerm) spliceOutsideQuotes(pos)
+              if (tp.isTerm) ctx.error(i"splice outside quotes", pos)
               tp
             }
           case tp: NamedType =>
@@ -418,14 +414,28 @@ class ReifyQuotes extends MacroTransformWithImplicits {
         val body1 = nested(isQuote = false).transform(splice.qualifier)
         body1.select(splice.name)
       }
-      else if (!inQuote && level == 0 && !ctx.owner.is(Transparent)) {
-        spliceOutsideQuotes(splice.pos)
-        splice
-      }
-      else {
+      else if (level == 1) {
         val (body1, quotes) = nested(isQuote = false).split(splice.qualifier)
         makeHole(body1, quotes, splice.tpe).withPos(splice.pos)
       }
+      else if (enclosingInlineds.nonEmpty) { // level 0 in an inline call
+        val spliceCtx = ctx.outer // drop the last `inlineContext`
+        val pos: SourcePosition = Decorators.sourcePos(enclosingInlineds.head.pos)(spliceCtx)
+        val evaluatedSplice = Splicer.splice(splice.qualifier, pos, macroClassLoader)(spliceCtx).withPos(splice.pos)
+        if (ctx.reporter.hasErrors) splice else transform(evaluatedSplice)
+      }
+      else if (!ctx.owner.is(Transparent)) { // level 0 outside a transparent definition
+        ctx.error(i"splice outside quotes or transparent method", splice.pos)
+        splice
+      }
+      else if (Splicer.canBeSpliced(splice.qualifier)) { // level 0 inside a transparent definition
+        nested(isQuote = false).split(splice.qualifier) // Just check PCP
+        splice
+      }
+      else { // level 0 inside a transparent definition
+        ctx.error("Malformed macro call. The contents of the ~ must call a static method and arguments must be quoted or transparent.".stripMargin, splice.pos)
+        splice
+      }
     }
 
     /** Transforms the contents of a nested splice
@@ -550,18 +560,6 @@ class ReifyQuotes extends MacroTransformWithImplicits {
             val last = enteredSyms
             stats.foreach(markDef)
             mapOverTree(last)
-          case Inlined(call, bindings, InlineSplice(spliced)) if !call.isEmpty =>
-            val tree2 =
-              if (level == 0) {
-                val evaluatedSplice = Splicer.splice(spliced, tree.pos, macroClassLoader).withPos(tree.pos)
-                if (ctx.reporter.hasErrors) EmptyTree
-                else transform(cpy.Inlined(tree)(call, bindings, evaluatedSplice))
-              }
-              else super.transform(tree)
-
-            // due to value-discarding which converts an { e } into { e; () })
-            if (tree.tpe =:= defn.UnitType) Block(tree2 :: Nil, Literal(Constant(())))
-            else tree2
           case _: Import =>
             tree
           case tree: DefDef if tree.symbol.is(Macro) && level == 0 =>

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

@@ -20,7 +20,6 @@ import dotty.tools.dotc.core.Constants.Constant
 import dotty.tools.dotc.tastyreflect.TastyImpl
 
 import scala.util.control.NonFatal
-import dotty.tools.dotc.util.Positions.Position
 import dotty.tools.dotc.util.SourcePosition
 
 import scala.reflect.ClassTag
@@ -35,7 +34,7 @@ object Splicer {
    *
    *  See: `ReifyQuotes`
    */
-  def splice(tree: Tree, pos: Position, classLoader: ClassLoader)(implicit ctx: Context): Tree = tree match {
+  def splice(tree: Tree, pos: SourcePosition, classLoader: ClassLoader)(implicit ctx: Context): Tree = tree match {
     case Quoted(quotedTree) => quotedTree
     case _ =>
       val interpreter = new Interpreter(pos, classLoader)
@@ -71,7 +70,7 @@ object Splicer {
   }
 
   /** Tree interpreter that evaluates the tree */
-  private class Interpreter(pos: Position, classLoader: ClassLoader)(implicit ctx: Context) extends AbstractInterpreter {
+  private class Interpreter(pos: SourcePosition, classLoader: ClassLoader)(implicit ctx: Context) extends AbstractInterpreter {
 
     type Result = Object
 
@@ -105,7 +104,7 @@ object Splicer {
 
     protected def interpretTastyContext()(implicit env: Env): Object =
       new TastyImpl(ctx) {
-        override def rootPosition: SourcePosition = SourcePosition(ctx.source, pos)
+        override def rootPosition: SourcePosition = pos
       }
 
     protected def interpretStaticMethodCall(fn: Tree, args: => List[Object])(implicit env: Env): Object = {
@@ -222,7 +221,7 @@ object Splicer {
     }
 
     /** Exception that stops interpretation if some issue is found */
-    private class StopInterpretation(val msg: String, val pos: Position) extends Exception
+    private class StopInterpretation(val msg: String, val pos: SourcePosition) extends Exception
 
   }
 

tests/neg/quote-exception/Macro_1.scala

@@ -4,5 +4,5 @@ object Macro_1 {
   transparent def foo(transparent b: Boolean): Unit = ~fooImpl(b)
   def fooImpl(b: Boolean): Expr[Unit] =
     if (b) '(println("foo(true)"))
-  else ???
+    else ???
 }

tests/neg/quote-macro-2-splices.scala

@@ -0,0 +1,11 @@
+import scala.quoted._
+
+object Macro {
+
+  transparent def foo(b: Boolean): Int = { // error
+    if (b) ~bar(true)
+    else ~bar(false)
+  }
+
+  def bar(b: Boolean): Expr[Int] = if (b) '(1) else '(0)
+}

tests/neg/quote-pcp-in-arg.scala

@@ -0,0 +1,6 @@
+import scala.quoted._
+
+object Foo {
+  transparent def foo(x: Int): Int = ~bar('{ '(x); x }) // error
+  def bar(i: Expr[Int]): Expr[Int] = i
+}

tests/neg/splice-in-top-level-splice-1.scala

@@ -0,0 +1,7 @@
+import scala.quoted._
+
+object Foo {
+  transparent def foo(): Int = ~bar(~x) // error
+  def x: Expr[Int] = '(1)
+  def bar(i: Int): Expr[Int] = i.toExpr
+}

tests/neg/splice-in-top-level-splice-2.scala

@@ -0,0 +1,6 @@
+import scala.quoted._
+
+object Foo {
+  transparent def foo(): Int = ~(~x) // error
+  def x: Expr[Expr[Int]] = '( '(1) )
+}