1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
|
/* NSC -- new Scala compiler
* Copyright 2005-2011 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package typechecker
import scala.collection.{ mutable, immutable }
import mutable.ListBuffer
import symtab.Flags._
/** This phase adds super accessors for all super calls that either
* appear in a trait or have as a target a member of some outer class.
* It also replaces references to parameter accessors with aliases
* by super references to these aliases. The phase also checks that
* symbols accessed from super are not abstract, or are overridden by
* an abstract override. Finally, the phase also mangles the names
* of class-members which are private up to an enclosing non-package
* class, in order to avoid overriding conflicts.
*
* @author Martin Odersky
* @version 1.0
*/
abstract class SuperAccessors extends transform.Transform with transform.TypingTransformers {
import global._
import definitions.{ UnitClass, isRepeatedParamType, isByNameParamType, Any_asInstanceOf }
import analyzer.{ restrictionError }
/** the following two members override abstract members in Transform */
val phaseName: String = "superaccessors"
protected def newTransformer(unit: CompilationUnit): Transformer =
new SuperAccTransformer(unit)
class SuperAccTransformer(unit: CompilationUnit) extends TypingTransformer(unit) {
private var validCurrentOwner = true
private val accDefs = mutable.Map[Symbol, ListBuffer[Tree]]()
private def storeAccessorDefinition(clazz: Symbol, tree: Tree) = {
val buf = accDefs.getOrElse(clazz, sys.error("no acc def buf for "+clazz))
buf += typers(clazz) typed tree
}
private def transformArgs(params: List[Symbol], args: List[Tree]) = {
treeInfo.mapMethodParamsAndArgs(params, args) { (param, arg) =>
if (isByNameParamType(param.tpe))
withInvalidOwner { checkPackedConforms(transform(arg), param.tpe.typeArgs.head) }
else transform(arg)
}
}
private def checkPackedConforms(tree: Tree, pt: Type): Tree = {
if (tree.tpe exists (_.typeSymbol.isExistentialSkolem)) {
val packed = localTyper.packedType(tree, NoSymbol)
if (!(packed <:< pt)) {
val errorContext = localTyper.context.make(localTyper.context.tree)
errorContext.reportGeneralErrors = true
analyzer.newTyper(errorContext).infer.typeError(tree.pos, packed, pt)
}
}
tree
}
/** Check that a class and its companion object to not both define
* a class or module with same name
*/
private def checkCompanionNameClashes(sym: Symbol) =
if (!sym.owner.isModuleClass) {
val linked = sym.owner.linkedClassOfClass
if (linked != NoSymbol) {
var other = linked.info.decl(sym.name.toTypeName).filter(_.isClass)
if (other == NoSymbol)
other = linked.info.decl(sym.name.toTermName).filter(_.isModule)
if (other != NoSymbol)
unit.error(sym.pos, "name clash: "+sym.owner+" defines "+sym+
"\nand its companion "+sym.owner.companionModule+" also defines "+
other)
}
}
private def transformSuperSelect(tree: Tree): Tree = tree match {
case Select(sup @ Super(_, mix), name) =>
val sym = tree.symbol
val clazz = sup.symbol
if (sym.isDeferred) {
val member = sym.overridingSymbol(clazz);
if (mix != tpnme.EMPTY || member == NoSymbol ||
!((member hasFlag ABSOVERRIDE) && member.isIncompleteIn(clazz)))
unit.error(tree.pos, ""+sym+sym.locationString+" is accessed from super. It may not be abstract "+
"unless it is overridden by a member declared `abstract' and `override'");
}
if (tree.isTerm && mix == tpnme.EMPTY &&
(clazz.isTrait || clazz != currentOwner.enclClass || !validCurrentOwner)) {
val supername = nme.superName(sym.name)
var superAcc = clazz.info.decl(supername).suchThat(_.alias == sym)
if (superAcc == NoSymbol) {
debuglog("add super acc " + sym + sym.locationString + " to `" + clazz);//debug
superAcc = clazz.newMethod(supername, tree.pos, SUPERACCESSOR | PRIVATE) setAlias sym
var superAccTpe = clazz.thisType.memberType(sym)
if (sym.isModule && !sym.isMethod) {
// the super accessor always needs to be a method. See #231
superAccTpe = NullaryMethodType(superAccTpe)
}
superAcc setInfoAndEnter (superAccTpe cloneInfo superAcc)
storeAccessorDefinition(clazz, DefDef(superAcc, EmptyTree))
}
atPos(sup.pos) {
Select(gen.mkAttributedThis(clazz), superAcc) setType tree.tpe;
}
} else {
tree
}
case _ =>
assert(tree.tpe.isError, tree)
tree
}
// Disallow some super.XX calls targeting Any methods which would
// otherwise lead to either a compiler crash or runtime failure.
private lazy val isDisallowed = {
import definitions._
Set(Any_isInstanceOf, Object_isInstanceOf, Any_asInstanceOf, Object_asInstanceOf, Object_==, Object_!=, Object_##)
}
override def transform(tree: Tree): Tree = {
val sym = tree.symbol
def mayNeedProtectedAccessor(sel: Select, args: List[Tree], goToSuper: Boolean) =
if (needsProtectedAccessor(sym, tree.pos)) {
debuglog("Adding protected accessor for " + tree)
transform(makeAccessor(sel, args))
}
else if (goToSuper) super.transform(tree)
else tree
try tree match {
// Don't transform patterns or strange trees will reach the matcher (ticket #4062)
case CaseDef(pat, guard, body) =>
treeCopy.CaseDef(tree, pat, transform(guard), transform(body))
case ClassDef(_, _, _, _) =>
checkCompanionNameClashes(sym)
val decls = sym.info.decls
for (s <- decls) {
if (s.privateWithin.isClass && !s.isProtected && !s.privateWithin.isModuleClass &&
!s.hasFlag(EXPANDEDNAME) && !s.isConstructor) {
decls.unlink(s)
s.expandName(s.privateWithin)
decls.enter(s)
}
}
if (settings.verbose.value && forScaladoc && !sym.isAnonymousClass) {
println("========== scaladoc of "+sym+" =============================")
println(toJavaDoc(expandedDocComment(sym)))
for (member <- sym.info.members) {
println(member+":"+sym.thisType.memberInfo(member)+"\n"+
toJavaDoc(expandedDocComment(member, sym)))
for ((useCase, comment, pos) <- useCases(member, sym)) {
println("usecase "+useCase+":"+useCase.info)
println(toJavaDoc(comment))
}
}
}
super.transform(tree)
case ModuleDef(_, _, _) =>
checkCompanionNameClashes(sym)
super.transform(tree)
case Template(parents, self, body) =>
val ownAccDefs = new ListBuffer[Tree]
accDefs(currentOwner) = ownAccDefs
// ugly hack... normally, the following line should not be
// necessary, the 'super' method taking care of that. but because
// that one is iterating through parents (and we dont want that here)
// we need to inline it.
curTree = tree
val body1 = atOwner(currentOwner)(transformTrees(body))
accDefs -= currentOwner
ownAccDefs ++= body1
treeCopy.Template(tree, parents, self, ownAccDefs.toList)
case TypeApply(sel @ Select(This(_), name), args) =>
mayNeedProtectedAccessor(sel, args, false)
case sel @ Select(qual @ This(_), name) =>
// warn if they are selecting a private[this] member which
// also exists in a superclass, because they may be surprised
// to find out that a constructor parameter will shadow a
// field. See SI-4762.
if (settings.lint.value) {
if (sym.isPrivateLocal && sym.paramss.isEmpty) {
qual.symbol.ancestors foreach { parent =>
parent.info.decls filterNot (x => x.isPrivate || x.hasLocalFlag) foreach { m2 =>
if (sym.name == m2.name && m2.isGetter && m2.accessed.isMutable) {
unit.warning(sel.pos,
sym.accessString + " " + sym.fullLocationString + " shadows mutable " + m2.name
+ " inherited from " + m2.owner + ". Changes to " + m2.name + " will not be visible within "
+ sym.owner + " - you may want to give them distinct names."
)
}
}
}
}
}
// direct calls to aliases of param accessors to the superclass in order to avoid
// duplicating fields.
if (sym.isParamAccessor && sym.alias != NoSymbol) {
val result = localTyper.typed {
Select(
Super(qual, tpnme.EMPTY/*qual.symbol.info.parents.head.symbol.name*/) setPos qual.pos,
sym.alias) setPos tree.pos
}
debuglog("alias replacement: " + tree + " ==> " + result);//debug
localTyper.typed(gen.maybeMkAsInstanceOf(transformSuperSelect(result), sym.tpe, sym.alias.tpe, true))
}
else mayNeedProtectedAccessor(sel, List(EmptyTree), false)
case Select(Super(_, mix), name) =>
if (sym.isValue && !sym.isMethod || sym.hasAccessorFlag) {
unit.error(tree.pos, "super may be not be used on "+ sym.accessedOrSelf)
}
else if (isDisallowed(sym)) {
unit.error(tree.pos, "super not allowed here: use this." + name.decode + " instead")
}
transformSuperSelect(tree)
case TypeApply(sel @ Select(qual, name), args) =>
mayNeedProtectedAccessor(sel, args, true)
case sel @ Select(qual, name) =>
mayNeedProtectedAccessor(sel, List(EmptyTree), true)
case Assign(lhs @ Select(qual, name), rhs) =>
if (lhs.symbol.isVariable &&
lhs.symbol.isJavaDefined &&
needsProtectedAccessor(lhs.symbol, tree.pos)) {
debuglog("Adding protected setter for " + tree)
val setter = makeSetter(lhs);
debuglog("Replaced " + tree + " with " + setter);
transform(localTyper.typed(Apply(setter, List(qual, rhs))))
} else
super.transform(tree)
case Apply(fn, args) =>
assert(fn.tpe != null, tree)
treeCopy.Apply(tree, transform(fn), transformArgs(fn.tpe.params, args))
case Function(vparams, body) =>
withInvalidOwner {
treeCopy.Function(tree, vparams, transform(body))
}
case _ =>
super.transform(tree)
}
catch {
case ex : AssertionError =>
if (sym != null && sym != NoSymbol)
Console.println("TRANSFORM: " + tree.symbol.sourceFile)
Console.println("TREE: " + tree)
throw ex
}
}
override def atOwner[A](owner: Symbol)(trans: => A): A = {
if (owner.isClass) validCurrentOwner = true
super.atOwner(owner)(trans)
}
private def withInvalidOwner[A](trans: => A): A = {
val prevValidCurrentOwner = validCurrentOwner
validCurrentOwner = false
val result = trans
validCurrentOwner = prevValidCurrentOwner
result
}
/** Add a protected accessor, if needed, and return a tree that calls
* the accessor and returns the same member. The result is already
* typed.
*/
private def makeAccessor(tree: Select, targs: List[Tree]): Tree = {
val Select(qual, name) = tree
val sym = tree.symbol
val clazz = hostForAccessorOf(sym, currentOwner.enclClass)
assert(clazz != NoSymbol, sym)
debuglog("Decided for host class: " + clazz)
val accName = nme.protName(sym.originalName)
val hasArgs = sym.tpe.paramSectionCount > 0
val memberType = refChecks.toScalaRepeatedParam(sym.tpe) // fix for #2413
// if the result type depends on the this type of an enclosing class, the accessor
// has to take an object of exactly this type, otherwise it's more general
val objType = if (isThisType(memberType.finalResultType)) clazz.thisType else clazz.typeOfThis
val accType = (protAcc: Symbol) => memberType match {
case PolyType(tparams, restpe) =>
// luc: question to author: should the tparams symbols not be cloned and get a new owner (protAcc)?
PolyType(tparams, MethodType(List(protAcc.newSyntheticValueParam(objType)),
restpe.cloneInfo(protAcc).asSeenFrom(qual.tpe, sym.owner)))
case _ =>
MethodType(List(protAcc.newSyntheticValueParam(objType)),
memberType.cloneInfo(protAcc).asSeenFrom(qual.tpe, sym.owner))
}
val protAcc = clazz.info.decl(accName).suchThat(s => s == NoSymbol || s.tpe =:= accType(s)) orElse {
val newAcc = clazz.newMethod(nme.protName(sym.originalName), tree.pos)
newAcc setInfoAndEnter accType(newAcc)
val code = DefDef(newAcc, {
val (receiver :: _) :: tail = newAcc.paramss
val base: Tree = Select(Ident(receiver), sym)
val allParamTypes = mapParamss(sym)(_.tpe)
val args = map2(tail, allParamTypes)((params, tpes) => map2(params, tpes)(makeArg(_, receiver, _)))
args.foldLeft(base)(Apply(_, _))
})
debuglog("" + code)
storeAccessorDefinition(clazz, code)
newAcc
}
val selection = Select(This(clazz), protAcc)
def mkApply(fn: Tree) = Apply(fn, qual :: Nil)
val res = atPos(tree.pos) {
targs.head match {
case EmptyTree => mkApply(selection)
case _ => mkApply(TypeApply(selection, targs))
}
}
debuglog("Replaced " + tree + " with " + res)
if (hasArgs) localTyper.typedOperator(res) else localTyper.typed(res)
}
/** Adapt the given argument in call to protected member.
* Adaptation may add a cast to a path-dependent type, for instance
*
* def prot$m(obj: Outer)(x: Inner) = obj.m(x.asInstanceOf[obj.Inner]).
*
* such a cast might be necessary when m expects an Outer.this.Inner (the
* outer of 'obj' and 'x' have to be the same). This restriction can't be
* expressed in the type system (but is implicit when defining method m).
*
* Also, it calls using repeated parameters are ascribed with ': _*'
*/
private def makeArg(v: Symbol, obj: Symbol, pt: Type): Tree = {
// owner class
val clazz = pt match {
case TypeRef(pre, _, _) => thisTypeOfPath(pre)
case _ => NoSymbol
}
val result = gen.paramToArg(v)
if (clazz != NoSymbol && (obj.tpe.typeSymbol isSubClass clazz)) // path-dependent type
gen.mkAsInstanceOf(result, pt.asSeenFrom(singleType(NoPrefix, obj), clazz))
else
result
}
/** Add an accessor for field, if needed, and return a selection tree for it .
* The result is not typed.
*/
private def makeSetter(tree: Select): Tree = {
val field = tree.symbol
val clazz = hostForAccessorOf(field, currentOwner.enclClass)
assert(clazz != NoSymbol, field)
debuglog("Decided for host class: " + clazz)
val accName = nme.protSetterName(field.originalName)
val protectedAccessor = clazz.info decl accName orElse {
val protAcc = clazz.newMethod(accName, field.pos)
val paramTypes = List(clazz.typeOfThis, field.tpe)
val params = protAcc newSyntheticValueParams paramTypes
val accessorType = MethodType(params, UnitClass.tpe)
protAcc setInfoAndEnter accessorType
val obj :: value :: Nil = params
storeAccessorDefinition(clazz, DefDef(protAcc, Assign(Select(Ident(obj), field.name), Ident(value))))
protAcc
}
atPos(tree.pos)(Select(This(clazz), protectedAccessor))
}
/** Does `sym` need an accessor when accessed from `currentOwner`?
* A special case arises for classes with explicit self-types. If the
* self type is a Java class, and a protected accessor is needed, we issue
* an error. If the self type is a Scala class, we don't add an accessor.
* An accessor is not needed if the access boundary is larger than the
* enclosing package, since that translates to 'public' on the host sys.
* (as Java has no real package nesting).
*
* If the access happens inside a 'trait', access is more problematic since
* the implementation code is moved to an '$class' class which does not
* inherit anything. Since we can't (yet) add accessors for 'required'
* classes, this has to be signaled as error.
*/
private def needsProtectedAccessor(sym: Symbol, pos: Position): Boolean = {
val clazz = currentOwner.enclClass
def accessibleThroughSubclassing =
validCurrentOwner && clazz.thisSym.isSubClass(sym.owner) && !clazz.isTrait
def packageAccessBoundry(sym: Symbol) = {
val b = sym.accessBoundary(sym.owner)
if (b.isPackageClass) b
else b.enclosingPackageClass
}
val isCandidate = (
sym.isProtected
&& sym.isJavaDefined
&& !sym.isDefinedInPackage
&& !accessibleThroughSubclassing
&& (sym.owner.enclosingPackageClass != currentOwner.enclosingPackageClass)
&& (sym.owner.enclosingPackageClass == packageAccessBoundry(sym))
)
val host = hostForAccessorOf(sym, clazz)
def isSelfType = !(host.tpe <:< host.typeOfThis) && {
if (host.typeOfThis.typeSymbol.isJavaDefined)
restrictionError(pos, unit,
"%s accesses protected %s from self type %s.".format(clazz, sym, host.typeOfThis)
)
true
}
def isJavaProtected = host.isTrait && sym.isJavaDefined && {
restrictionError(pos, unit,
"""|%s accesses protected %s inside a concrete trait method.
|Add an accessor in a class extending %s as a workaround.""".stripMargin.format(
clazz, sym, sym.enclClass)
)
true
}
isCandidate && !host.isPackageClass && !isSelfType && !isJavaProtected
}
/** Return the innermost enclosing class C of referencingClass for which either
* of the following holds:
* - C is a subclass of sym.owner or
* - C is declared in the same package as sym's owner
*/
private def hostForAccessorOf(sym: Symbol, referencingClass: Symbol): Symbol = {
if (referencingClass.isSubClass(sym.owner.enclClass)
|| referencingClass.thisSym.isSubClass(sym.owner.enclClass)
|| referencingClass.enclosingPackageClass == sym.owner.enclosingPackageClass) {
assert(referencingClass.isClass)
referencingClass
} else if(referencingClass.owner.enclClass != NoSymbol)
hostForAccessorOf(sym, referencingClass.owner.enclClass)
else referencingClass
}
/** For a path-dependent type, return the this type. */
private def thisTypeOfPath(path: Type): Symbol = path match {
case ThisType(outerSym) => outerSym
case SingleType(rest, _) => thisTypeOfPath(rest)
case _ => NoSymbol
}
/** Is 'tpe' the type of a member of an enclosing class? */
private def isThisType(tpe: Type): Boolean = tpe match {
case ThisType(sym) => sym.isClass && !sym.isPackageClass
case TypeRef(pre, _, _) => isThisType(pre)
case SingleType(pre, _) => isThisType(pre)
case RefinedType(parents, _) => parents exists isThisType
case AnnotatedType(_, tp, _) => isThisType(tp)
case _ => false
}
}
}
|