WIP Expand macros in typer

Author: nicolasstucki

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

@@ -122,25 +122,22 @@ object Staging {
         if (splice1.isType) splice1
         else addSpliceCast(splice1)
       }
-      else if (enclosingInlineds.nonEmpty) { // level 0 in an inlined call
-        val spliceCtx = ctx.outer // drop the last `inlineContext`
-        val pos: SourcePosition = spliceCtx.source.atSpan(enclosingInlineds.head.span)
-        val evaluatedSplice = Splicer.splice(splice.qualifier, pos, macroClassLoader)(spliceCtx).withSpan(splice.span)
-        if (ctx.reporter.hasErrors) splice else transform(evaluatedSplice)
-      }
-      else if (!ctx.owner.isInlineMethod) { // level 0 outside an inline method
-        ctx.error(i"splice outside quotes or inline method", splice.sourcePos)
-        splice
-      }
-      else if (Splicer.canBeSpliced(splice.qualifier)) { // level 0 inside an inline definition
-        transform(splice.qualifier)(spliceContext) // Just check PCP
-        splice
-      }
-      else { // level 0 inside an inline definition
-        ctx.error(
-          "Malformed macro call. The contents of the ~ must call a static method and arguments must be quoted or inline.",
-          splice.sourcePos)
-        splice
+      else {
+        assert(!enclosingInlineds.nonEmpty, "unexpanded macro")
+        if (!ctx.owner.isInlineMethod) { // level 0 outside an inline method
+          ctx.error(i"splice outside quotes or inline method", splice.sourcePos)
+          splice
+        }
+        else if (Splicer.canBeSpliced(splice.qualifier)) { // level 0 inside an inline definition
+          transform(splice.qualifier)(spliceContext) // Just check PCP
+          splice
+        }
+        else { // level 0 inside an inline definition
+          ctx.error(
+            "Malformed macro call. The contents of the ~ must call a static method and arguments must be quoted or inline.",
+            splice.sourcePos)
+          splice
+        }
       }
     }
 

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

@@ -2,7 +2,7 @@ package dotty.tools
 package dotc
 package typer
 
-import ast._
+import ast.{TreeInfo, tpd, _}
 import Trees._
 import core._
 import Flags._
@@ -26,7 +26,8 @@ import collection.mutable
 import reporting.trace
 import util.Spans.Span
 import util.SourcePosition
-import ast.TreeInfo
+import dotty.tools.dotc.core.quoted.Spliced
+import dotty.tools.dotc.transform.{Splicer, TreeMapWithStages}
 
 object Inliner {
   import tpd._
@@ -106,7 +107,7 @@ object Inliner {
     else if (enclosingInlineds.length < ctx.settings.XmaxInlines.value) {
       val body = bodyToInline(tree.symbol) // can typecheck the tree and thereby produce errors
       if (ctx.reporter.hasErrors) tree
-      else new Inliner(tree, body).inlined(pt)
+      else new Inliner(tree, body).inlined(pt, tree.sourcePos)
     }
     else
       errorTree(
@@ -359,7 +360,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
     }
 
   /** The Inlined node representing the inlined call */
-  def inlined(pt: Type): Tree = {
+  def inlined(pt: Type, sourcePos: SourcePosition): Tree = {
 
     if (callTypeArgs.length == 1)
       if (inlinedMethod == defn.Compiletime_constValue) {
@@ -467,8 +468,13 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
       // The normalized bindings collected in `bindingsBuf`
       bindingsBuf.transform(reducer.normalizeBinding(_)(inlineCtx))
 
+      // Evaluate the top level ~ if it is a macro
+      val expansion0 =
+        if (call.symbol.is(Macro) && TreeMapWithStages.level == 0) expandMacro(expansion, sourcePos)
+        else expansion
+
       // Run a typing pass over the inlined tree. See InlineTyper for details.
-      val expansion1 = inlineTyper.typed(expansion, pt)(inlineCtx)
+      val expansion1 = inlineTyper.typed(expansion0, pt)(inlineCtx)
 
       if (ctx.settings.verbose.value) {
         inlining.println(i"to inline = $rhsToInline")
@@ -487,6 +493,23 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
     }
   }
 
+  private def expandMacro(expansion: Tree, pos: SourcePosition) = {
+    // TODO cache macro classloader
+    val urls = ctx.settings.classpath.value.split(java.io.File.pathSeparatorChar).map(cp => java.nio.file.Paths.get(cp).toUri.toURL)
+    val macroClassLoader = new java.net.URLClassLoader(urls, getClass.getClassLoader)
+
+    new TreeMap() {
+      override def transform(tree1: tpd.Tree)(implicit ctx: Context): tpd.Tree = tree1 match {
+        case Spliced(splicedBody) =>
+          val evaluatedSplice = Splicer.splice(splicedBody, pos, macroClassLoader).withSpan(tree1.span)
+          if (ctx.reporter.hasErrors) EmptyTree
+          else evaluatedSplice
+        case _ =>
+          super.transform(tree1)
+      }
+    }.transform(expansion)
+  }
+
   /** A utility object offering methods for rewriting inlined code */
   object reducer {
 

tests/neg/quote-whitebox/Macro_1.scala

@@ -0,0 +1,9 @@
+import scala.quoted._
+
+object Macros {
+  inline def defaultOf(inline str: String) <: Any = ~defaultOfImpl(str)
+  def defaultOfImpl(str: String): Expr[Any] = str match {
+    case "int" => '(1)
+    case "string" => '("a")
+  }
+}

tests/neg/quote-whitebox/Test_2.scala

@@ -0,0 +1,8 @@
+import Macros._
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    val a: String = defaultOf("int") // error
+    val b: Int = defaultOf("string") // error
+  }
+}

tests/run/quote-whitebox.check

@@ -0,0 +1,2 @@
+1
+a

tests/run/quote-whitebox/Macro_1.scala

@@ -0,0 +1,9 @@
+import scala.quoted._
+
+object Macros {
+  inline def defaultOf(inline str: String) <: Any = ~defaultOfImpl(str)
+  def defaultOfImpl(str: String): Expr[Any] = str match {
+    case "int" => '(1)
+    case "string" => '("a")
+  }
+}

tests/run/quote-whitebox/Test_2.scala

@@ -0,0 +1,10 @@
+import Macros._
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    val a: Int = defaultOf("int")
+    val b: String = defaultOf("string")
+    println(a)
+    println(b)
+  }
+}