Merge pull request #4868 from dotty-staging/refactor-splice-code

Move all logic handling splices into `splice`

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.
@@ -242,10 +242,6 @@ 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
@@ -304,7 +300,7 @@ 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 =>
@@ -424,14 +420,28 @@ 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 inlined 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
@@ -549,18 +559,6 @@ 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) )
+}