diff options
Diffstat (limited to 'src')
7 files changed, 45 insertions, 16 deletions
diff --git a/src/compiler/scala/reflect/macros/runtime/Aliases.scala b/src/compiler/scala/reflect/macros/runtime/Aliases.scala index ff870e728e..96cf50e498 100644 --- a/src/compiler/scala/reflect/macros/runtime/Aliases.scala +++ b/src/compiler/scala/reflect/macros/runtime/Aliases.scala @@ -28,4 +28,9 @@ trait Aliases { override def typeTag[T](implicit ttag: TypeTag[T]) = ttag override def weakTypeOf[T](implicit attag: WeakTypeTag[T]): Type = attag.tpe override def typeOf[T](implicit ttag: TypeTag[T]): Type = ttag.tpe + + type ImplicitCandidate = (Type, Tree) + implicit class RichOpenImplicit(oi: universe.analyzer.OpenImplicit) { + def toImplicitCandidate = (oi.pt, oi.tree) + } }
\ No newline at end of file diff --git a/src/compiler/scala/reflect/macros/runtime/Enclosures.scala b/src/compiler/scala/reflect/macros/runtime/Enclosures.scala index be5f2dbe83..2a4a22f81c 100644 --- a/src/compiler/scala/reflect/macros/runtime/Enclosures.scala +++ b/src/compiler/scala/reflect/macros/runtime/Enclosures.scala @@ -13,12 +13,12 @@ trait Enclosures { // vals are eager to simplify debugging // after all we wouldn't save that much time by making them lazy - val macroApplication: Tree = expandee - val enclosingClass: Tree = enclTrees collectFirst { case x: ImplDef => x } getOrElse EmptyTree - val enclosingImplicits: List[(Type, Tree)] = site.openImplicits - val enclosingMacros: List[Context] = this :: universe.analyzer.openMacros // include self - val enclosingMethod: Tree = site.enclMethod.tree - val enclosingPosition: Position = if (enclPoses.isEmpty) NoPosition else enclPoses.head.pos - val enclosingUnit: CompilationUnit = universe.currentRun.currentUnit - val enclosingRun: Run = universe.currentRun + val macroApplication: Tree = expandee + val enclosingClass: Tree = enclTrees collectFirst { case x: ImplDef => x } getOrElse EmptyTree + val enclosingImplicits: List[ImplicitCandidate] = site.openImplicits.map(_.toImplicitCandidate) + val enclosingMacros: List[Context] = this :: universe.analyzer.openMacros // include self + val enclosingMethod: Tree = site.enclMethod.tree + val enclosingPosition: Position = if (enclPoses.isEmpty) NoPosition else enclPoses.head.pos + val enclosingUnit: CompilationUnit = universe.currentRun.currentUnit + val enclosingRun: Run = universe.currentRun } diff --git a/src/compiler/scala/reflect/macros/runtime/Typers.scala b/src/compiler/scala/reflect/macros/runtime/Typers.scala index f9add91b9a..8dc9bdeb7a 100644 --- a/src/compiler/scala/reflect/macros/runtime/Typers.scala +++ b/src/compiler/scala/reflect/macros/runtime/Typers.scala @@ -6,7 +6,7 @@ trait Typers { def openMacros: List[Context] = this :: universe.analyzer.openMacros - def openImplicits: List[(Type, Tree)] = callsiteTyper.context.openImplicits + def openImplicits: List[ImplicitCandidate] = callsiteTyper.context.openImplicits.map(_.toImplicitCandidate) /** * @see [[scala.tools.reflect.Toolbox.typeCheck]] @@ -62,4 +62,4 @@ trait Typers { def resetAllAttrs(tree: Tree): Tree = universe.resetAllAttrs(tree) def resetLocalAttrs(tree: Tree): Tree = universe.resetLocalAttrs(tree) -}
\ No newline at end of file +} diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala index 6c2945cad3..3fe98ed127 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala @@ -120,7 +120,7 @@ trait Contexts { self: Analyzer => // not inherited to child contexts var depth: Int = 0 var imports: List[ImportInfo] = List() // currently visible imports - var openImplicits: List[(Type,Tree)] = List() // types for which implicit arguments + var openImplicits: List[OpenImplicit] = List() // types for which implicit arguments // are currently searched // for a named application block (Tree) the corresponding NamedApplyInfo var namedApplyBlockInfo: Option[(Tree, NamedApplyInfo)] = None diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala index 04e0b9d653..81e47eecb0 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala @@ -219,6 +219,10 @@ trait Implicits { override def toString = name + ": " + tpe } + /** A class which is used to track pending implicits to prevent infinite implicit searches. + */ + case class OpenImplicit(info: ImplicitInfo, pt: Type, tree: Tree) + /** A sentinel indicating no implicit was found */ val NoImplicitInfo = new ImplicitInfo(null, NoType, NoSymbol) { // equals used to be implemented in ImplicitInfo with an `if(this eq NoImplicitInfo)` @@ -406,20 +410,32 @@ trait Implicits { * @pre `info.tpe` does not contain an error */ private def typedImplicit(info: ImplicitInfo, ptChecked: Boolean, isLocal: Boolean): SearchResult = { - (context.openImplicits find { case (tp, tree1) => tree1.symbol == tree.symbol && dominates(pt, tp)}) match { + // SI-7167 let implicit macros decide what amounts for a divergent implicit search + // imagine a macro writer which wants to synthesize a complex implicit Complex[T] by making recursive calls to Complex[U] for its parts + // e.g. we have `class Foo(val bar: Bar)` and `class Bar(val x: Int)` + // then it's quite reasonable for the macro writer to synthesize Complex[Foo] by calling `inferImplicitValue(typeOf[Complex[Bar])` + // however if we didn't insert the `info.sym.isMacro` check here, then under some circumstances + // (e.g. as described here http://groups.google.com/group/scala-internals/browse_thread/thread/545462b377b0ac0a) + // `dominates` might decide that `Bar` dominates `Foo` and therefore a recursive implicit search should be prohibited + // now when we yield control of divergent expansions to the macro writer, what happens next? + // in the worst case, if the macro writer is careless, we'll get a StackOverflowException from repeated macro calls + // otherwise, the macro writer could check `c.openMacros` and `c.openImplicits` and do `c.abort` when expansions are deemed to be divergent + // upon receiving `c.abort` the typechecker will decide that the corresponding implicit search has failed + // which will fail the entire stack of implicit searches, producing a nice error message provided by the programmer + (context.openImplicits find { case OpenImplicit(info, tp, tree1) => !info.sym.isMacro && tree1.symbol == tree.symbol && dominates(pt, tp)}) match { case Some(pending) => //println("Pending implicit "+pending+" dominates "+pt+"/"+undetParams) //@MDEBUG throw DivergentImplicit case None => try { - context.openImplicits = (pt, tree) :: context.openImplicits + context.openImplicits = OpenImplicit(info, pt, tree) :: context.openImplicits // println(" "*context.openImplicits.length+"typed implicit "+info+" for "+pt) //@MDEBUG typedImplicit0(info, ptChecked, isLocal) } catch { case ex: DivergentImplicit => //println("DivergentImplicit for pt:"+ pt +", open implicits:"+context.openImplicits) //@MDEBUG if (context.openImplicits.tail.isEmpty) { - if (!(pt.isErroneous)) + if (!pt.isErroneous && !info.sym.isMacro) DivergingImplicitExpansionError(tree, pt, info.sym)(context) SearchFailure } else { diff --git a/src/reflect/scala/reflect/macros/Enclosures.scala b/src/reflect/scala/reflect/macros/Enclosures.scala index c48656b366..a4ad71c348 100644 --- a/src/reflect/scala/reflect/macros/Enclosures.scala +++ b/src/reflect/scala/reflect/macros/Enclosures.scala @@ -29,8 +29,12 @@ trait Enclosures { */ val enclosingMacros: List[Context] - /** Types along with corresponding trees for which implicit arguments are currently searched. + /** Information about one of the currently considered implicit candidates. + * Candidates are used in plural form, because implicit parameters may themselves have implicit parameters, + * hence implicit searches can recursively trigger other implicit searches. + * * Can be useful to get information about an application with an implicit parameter that is materialized during current macro expansion. + * If we're in an implicit macro being expanded, it's included in this list. * * Unlike `openImplicits`, this is a val, which means that it gets initialized when the context is created * and always stays the same regardless of whatever happens during macro expansion. diff --git a/src/reflect/scala/reflect/macros/Typers.scala b/src/reflect/scala/reflect/macros/Typers.scala index 427e7854b2..d36636a6d2 100644 --- a/src/reflect/scala/reflect/macros/Typers.scala +++ b/src/reflect/scala/reflect/macros/Typers.scala @@ -24,8 +24,12 @@ trait Typers { */ def openMacros: List[Context] - /** Types along with corresponding trees for which implicit arguments are currently searched. + /** Information about one of the currently considered implicit candidates. + * Candidates are used in plural form, because implicit parameters may themselves have implicit parameters, + * hence implicit searches can recursively trigger other implicit searches. + * * Can be useful to get information about an application with an implicit parameter that is materialized during current macro expansion. + * If we're in an implicit macro being expanded, it's included in this list. * * Unlike `enclosingImplicits`, this is a def, which means that it gets recalculated on every invocation, * so it might change depending on what is going on during macro expansion. |