Merge pull request #4899 from dotty-staging/fix-#4515

Fix #4515: Synthesize implicit type tags in transparent methods

Author: nicolasstucki

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

@@ -686,8 +686,11 @@ class Definitions {
   def Unpickler_liftedExpr = ctx.requiredMethod("scala.runtime.quoted.Unpickler.liftedExpr")
   def Unpickler_unpickleType = ctx.requiredMethod("scala.runtime.quoted.Unpickler.unpickleType")
 
-  lazy val TastyTopLevelSpliceModule = ctx.requiredModule("scala.tasty.TopLevelSplice")
-    lazy val TastyTopLevelSplice_tastyContext = TastyTopLevelSpliceModule.requiredMethod("tastyContext")
+  lazy val TastyTastyType = ctx.requiredClassRef("scala.tasty.Tasty")
+  def TastyTastyClass(implicit ctx: Context) = TastyTastyType.symbol.asClass
+
+  lazy val TastyTastyModule = ctx.requiredModule("scala.tasty.Tasty")
+    lazy val TastyTasty_macroContext = TastyTastyModule.requiredMethod("macroContext")
 
   lazy val EqType = ctx.requiredClassRef("scala.Eq")
   def EqClass(implicit ctx: Context) = EqType.symbol.asClass

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

@@ -237,7 +237,7 @@ class ReifyQuotes extends MacroTransformWithImplicits {
     def levelOK(sym: Symbol)(implicit ctx: Context): Boolean = levelOf.get(sym) match {
       case Some(l) =>
         l == level ||
-        level == -1 && sym == defn.TastyTopLevelSplice_tastyContext
+        level == -1 && sym == defn.TastyTasty_macroContext
       case None =>
         !sym.is(Param) || levelOK(sym.owner)
     }

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

@@ -268,7 +268,7 @@ object Splicer {
       case Literal(Constant(value)) =>
         interpretLiteral(value)
 
-      case _ if tree.symbol == defn.TastyTopLevelSplice_tastyContext =>
+      case _ if tree.symbol == defn.TastyTasty_macroContext =>
         interpretTastyContext()
 
       case StaticMethodCall(fn, args) =>
@@ -286,6 +286,8 @@ object Splicer {
       case NamedArg(_, arg) => interpretTree(arg)
       case Ident(name) if env.contains(name) => env(name)
 
+      case Inlined(EmptyTree, Nil, expansion) => interpretTree(expansion)
+
       case _ => unexpectedTree(tree)
     }
 

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

@@ -620,10 +620,16 @@ trait Implicits { self: Typer =>
         val tag = bindFreeVars(arg)
         if (bindFreeVars.ok) ref(defn.QuotedType_apply).appliedToType(tag)
         else EmptyTree
+      case arg :: Nil if ctx.inRewriteMethod =>
+        ref(defn.QuotedType_apply).appliedToType(arg)
       case _ =>
         EmptyTree
     }
 
+    def synthesizedTastyContext(formal: Type): Tree =
+      if (ctx.inRewriteMethod || enclosingInlineds.nonEmpty) ref(defn.TastyTasty_macroContext)
+      else EmptyTree
+
     /** If `formal` is of the form Eq[T, U], where no `Eq` instance exists for
      *  either `T` or `U`, synthesize `Eq.eqAny[T, U]` as solution.
      */
@@ -694,7 +700,8 @@ trait Implicits { self: Typer =>
         else
           trySpecialCase(defn.ClassTagClass, synthesizedClassTag,
             trySpecialCase(defn.QuotedTypeClass, synthesizedTypeTag,
-              trySpecialCase(defn.EqClass, synthesizedEq, failed)))
+              trySpecialCase(defn.TastyTastyClass, synthesizedTastyContext,
+                trySpecialCase(defn.EqClass, synthesizedEq, failed))))
     }
   }
 

library/src/scala/tasty/Tasty.scala

@@ -19,3 +19,8 @@ abstract class Tasty
     with TreeOps
     with TypeOrBoundsTreeOps
     with TypeOrBoundsOps
+
+object Tasty {
+  /** Compiler tasty context available in a top level ~ of a transparent macro */
+  def macroContext: Tasty = throw new Exception("Not in transparent macro.")
+}

library/src/scala/tasty/TopLevelSplice.scala

@@ -12,7 +12,7 @@ object Asserts {
   object Ops
 
   rewrite def macroAssert(cond: => Boolean): Unit =
-    ~impl('(cond))(TopLevelSplice.tastyContext) // FIXME infer TopLevelSplice.tastyContext within top level ~
+    ~impl('(cond))
 
   def impl(cond: Expr[Boolean])(implicit tasty: Tasty): Expr[Unit] = {
     import tasty._

tests/neg/tasty-macro-assert/quoted_1.scala

@@ -6,8 +6,7 @@ import scala.tasty.util._
 
 object Macros {
 
-  rewrite def testMacro: Unit =
-    ~impl(TopLevelSplice.tastyContext) // FIXME infer TopLevelSplice.tastyContext within top level ~
+  rewrite def testMacro: Unit = ~impl
 
   def impl(implicit tasty: Tasty): Expr[Unit] = {
     // 2 is a lifted constant

tests/run-with-compiler/tasty-extractors-constants-2/quoted_1.scala

@@ -0,0 +1,5 @@
+
+object Macro {
+  rewrite def foo[X](x: X): Unit = ~fooImpl('(x))
+  def fooImpl[X: quoted.Type](x: quoted.Expr[X]): quoted.Expr[Unit] = '()
+}

tests/run/i4515/Macro_1.scala

@@ -0,0 +1,6 @@
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    Macro.foo(4)
+  }
+}