diff options
Diffstat (limited to 'src/compiler/scala/tools/nsc/typechecker/Namers.scala')
| -rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/Namers.scala | 82 |
1 files changed, 54 insertions, 28 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala index 39e259fdfd..86bb99e7fa 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala @@ -1132,7 +1132,7 @@ trait Namers extends MethodSynthesis { } } - addDefaultGetters(meth, vparamss, tparams, overriddenSymbol(methResTp)) + addDefaultGetters(meth, ddef, vparamss, tparams, overriddenSymbol(methResTp)) // fast track macros, i.e. macros defined inside the compiler, are hardcoded // hence we make use of that and let them have whatever right-hand side they need @@ -1174,7 +1174,12 @@ trait Namers extends MethodSynthesis { * typechecked, the corresponding param would not yet have the "defaultparam" * flag. */ - private def addDefaultGetters(meth: Symbol, vparamss: List[List[ValDef]], tparams: List[TypeDef], overriddenSymbol: => Symbol) { + private def addDefaultGetters(meth: Symbol, ddef: DefDef, vparamss: List[List[ValDef]], tparams: List[TypeDef], overriddenSymbol: => Symbol) { + val DefDef(_, _, rtparams0, rvparamss0, _, _) = resetLocalAttrs(ddef.duplicate) + // having defs here is important to make sure that there's no sneaky tree sharing + // in methods with multiple default parameters + def rtparams = rtparams0.map(_.duplicate) + def rvparamss = rvparamss0.map(_.map(_.duplicate)) val methOwner = meth.owner val isConstr = meth.isConstructor val overridden = if (isConstr || !methOwner.isClass) NoSymbol else overriddenSymbol @@ -1206,23 +1211,36 @@ trait Namers extends MethodSynthesis { // vparamss.foldLeft(Nil: List[List[ValDef]]) { (previous, vparams) => assert(!overrides || vparams.length == baseParamss.head.length, ""+ meth.fullName + ", "+ overridden.fullName) + val rvparams = rvparamss(previous.length) var baseParams = if (overrides) baseParamss.head else Nil - for (vparam <- vparams) { + map2(vparams, rvparams)((vparam, rvparam) => { val sym = vparam.symbol // true if the corresponding parameter of the base class has a default argument val baseHasDefault = overrides && baseParams.head.hasDefault if (sym.hasDefault) { - // generate a default getter for that argument + // Create a "default getter", i.e. a DefDef that will calculate vparam.rhs + // for those who are going to call meth without providing an argument corresponding to vparam. + // After the getter is created, a corresponding synthetic symbol is created and entered into the parent namer. + // + // In the ideal world, this DefDef would be a simple one-liner that just returns vparam.rhs, + // but in scalac things are complicated in two different ways. + // + // 1) Because the underlying language is quite sophisticated, we must allow for those sophistications in our getter. + // Namely: a) our getter has to copy type parameters from the associated method (or the associated class + // if meth is a constructor), because vparam.rhs might refer to one of them, b) our getter has to copy + // preceding value parameter lists from the associated method, because again vparam.rhs might refer to one of them. + // + // 2) Because we have already assigned symbols to type and value parameters that we have to copy, we must jump through + // hoops in order to destroy them and allow subsequent naming create new symbols for our getter. Previously this + // was done in an overly brutal way akin to resetAllAttrs, but now we utilize a resetLocalAttrs-based approach. + // Still far from ideal, but at least enables things like run/macro-default-params that were previously impossible. + val oflag = if (baseHasDefault) OVERRIDE else 0 val name = nme.defaultGetterName(meth.name, posCounter) - // Create trees for the defaultGetter. Uses tools from Unapplies.scala - var deftParams = tparams map copyUntyped[TypeDef] - val defvParamss = mmap(previous) { p => - // in the default getter, remove the default parameter - val p1 = atPos(p.pos.focus) { ValDef(p.mods &~ DEFAULTPARAM, p.name, p.tpt.duplicate, EmptyTree) } - UnTyper.traverse(p1) - p1 + var defTparams = rtparams + val defVparamss = mmap(rvparamss.take(previous.length)){ rvp => + copyValDef(rvp)(mods = rvp.mods &~ DEFAULTPARAM, rhs = EmptyTree) } val parentNamer = if (isConstr) { @@ -1244,7 +1262,8 @@ trait Namers extends MethodSynthesis { return // fix #3649 (prevent crash in erroneous source code) } } - deftParams = cdef.tparams map copyUntypedInvariant + val ClassDef(_, _, rtparams, _) = resetLocalAttrs(cdef.duplicate) + defTparams = rtparams.map(rt => copyTypeDef(rt)(mods = rt.mods &~ (COVARIANT | CONTRAVARIANT))) nmr } else ownerNamer getOrElse { @@ -1255,23 +1274,30 @@ trait Namers extends MethodSynthesis { nmr } - // If the parameter type mentions any type parameter of the method, let the compiler infer the - // return type of the default getter => allow "def foo[T](x: T = 1)" to compile. - // This is better than always using Wildcard for inferring the result type, for example in - // def f(i: Int, m: Int => Int = identity _) = m(i) - // if we use Wildcard as expected, we get "Nothing => Nothing", and the default is not usable. - val names = deftParams map { case TypeDef(_, name, _, _) => name } - val subst = new TypeTreeSubstituter(names contains _) - - val defTpt = subst(copyUntyped(vparam.tpt match { - // default getter for by-name params - case AppliedTypeTree(_, List(arg)) if sym.hasFlag(BYNAMEPARAM) => arg - case t => t - })) - val defRhs = copyUntyped(vparam.rhs) + val defTpt = + // don't mess with tpt's of case copy default getters, because assigning something other than TypeTree() + // will break the carefully orchestrated naming/typing logic that involves enterCopyMethod and caseClassCopyMeth + if (meth.isCaseCopy) TypeTree() + else { + // If the parameter type mentions any type parameter of the method, let the compiler infer the + // return type of the default getter => allow "def foo[T](x: T = 1)" to compile. + // This is better than always using Wildcard for inferring the result type, for example in + // def f(i: Int, m: Int => Int = identity _) = m(i) + // if we use Wildcard as expected, we get "Nothing => Nothing", and the default is not usable. + // TODO: this is a very brittle approach; I sincerely hope that Denys's research into hygiene + // will open the doors to a much better way of doing this kind of stuff + val tparamNames = defTparams map { case TypeDef(_, name, _, _) => name } + val eraseAllMentionsOfTparams = new TypeTreeSubstituter(tparamNames contains _) + eraseAllMentionsOfTparams(rvparam.tpt match { + // default getter for by-name params + case AppliedTypeTree(_, List(arg)) if sym.hasFlag(BYNAMEPARAM) => arg + case t => t + }) + } + val defRhs = rvparam.rhs val defaultTree = atPos(vparam.pos.focus) { - DefDef(Modifiers(paramFlagsToDefaultGetter(meth.flags)) | oflag, name, deftParams, defvParamss, defTpt, defRhs) + DefDef(Modifiers(paramFlagsToDefaultGetter(meth.flags)) | oflag, name, defTparams, defVparamss, defTpt, defRhs) } if (!isConstr) methOwner.resetFlag(INTERFACE) // there's a concrete member now @@ -1286,7 +1312,7 @@ trait Namers extends MethodSynthesis { } posCounter += 1 if (overrides) baseParams = baseParams.tail - } + }) if (overrides) baseParamss = baseParamss.tail previous :+ vparams } |