Thu, 29 Jul 2010 15:56:25 +0100
6938454: Unable to determine generic type in program that compiles under Java 6
Summary: a redundant dubtyping check causes spurious inference failure
Reviewed-by: jjg
1 /*
2 * Copyright (c) 1999, 2008, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
26 package com.sun.tools.javac.comp;
28 import java.util.*;
29 import javax.tools.JavaFileObject;
30 import javax.tools.JavaFileManager;
32 import com.sun.tools.javac.code.*;
33 import com.sun.tools.javac.jvm.*;
34 import com.sun.tools.javac.tree.*;
35 import com.sun.tools.javac.util.*;
36 import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
37 import com.sun.tools.javac.util.List;
39 import com.sun.tools.javac.code.Type.*;
40 import com.sun.tools.javac.code.Symbol.*;
41 import com.sun.tools.javac.tree.JCTree.*;
43 import static com.sun.tools.javac.code.Flags.*;
44 import static com.sun.tools.javac.code.Kinds.*;
46 /** This class enters symbols for all encountered definitions into
47 * the symbol table. The pass consists of two phases, organized as
48 * follows:
49 *
50 * <p>In the first phase, all class symbols are intered into their
51 * enclosing scope, descending recursively down the tree for classes
52 * which are members of other classes. The class symbols are given a
53 * MemberEnter object as completer.
54 *
55 * <p>In the second phase classes are completed using
56 * MemberEnter.complete(). Completion might occur on demand, but
57 * any classes that are not completed that way will be eventually
58 * completed by processing the `uncompleted' queue. Completion
59 * entails (1) determination of a class's parameters, supertype and
60 * interfaces, as well as (2) entering all symbols defined in the
61 * class into its scope, with the exception of class symbols which
62 * have been entered in phase 1. (2) depends on (1) having been
63 * completed for a class and all its superclasses and enclosing
64 * classes. That's why, after doing (1), we put classes in a
65 * `halfcompleted' queue. Only when we have performed (1) for a class
66 * and all it's superclasses and enclosing classes, we proceed to
67 * (2).
68 *
69 * <p>Whereas the first phase is organized as a sweep through all
70 * compiled syntax trees, the second phase is demand. Members of a
71 * class are entered when the contents of a class are first
72 * accessed. This is accomplished by installing completer objects in
73 * class symbols for compiled classes which invoke the member-enter
74 * phase for the corresponding class tree.
75 *
76 * <p>Classes migrate from one phase to the next via queues:
77 *
78 * <pre>
79 * class enter -> (Enter.uncompleted) --> member enter (1)
80 * -> (MemberEnter.halfcompleted) --> member enter (2)
81 * -> (Todo) --> attribute
82 * (only for toplevel classes)
83 * </pre>
84 *
85 * <p><b>This is NOT part of any supported API.
86 * If you write code that depends on this, you do so at your own risk.
87 * This code and its internal interfaces are subject to change or
88 * deletion without notice.</b>
89 */
90 public class Enter extends JCTree.Visitor {
91 protected static final Context.Key<Enter> enterKey =
92 new Context.Key<Enter>();
94 Log log;
95 Symtab syms;
96 Check chk;
97 TreeMaker make;
98 ClassReader reader;
99 Annotate annotate;
100 MemberEnter memberEnter;
101 Types types;
102 Lint lint;
103 Names names;
104 JavaFileManager fileManager;
106 private final Todo todo;
108 public static Enter instance(Context context) {
109 Enter instance = context.get(enterKey);
110 if (instance == null)
111 instance = new Enter(context);
112 return instance;
113 }
115 protected Enter(Context context) {
116 context.put(enterKey, this);
118 log = Log.instance(context);
119 reader = ClassReader.instance(context);
120 make = TreeMaker.instance(context);
121 syms = Symtab.instance(context);
122 chk = Check.instance(context);
123 memberEnter = MemberEnter.instance(context);
124 types = Types.instance(context);
125 annotate = Annotate.instance(context);
126 lint = Lint.instance(context);
127 names = Names.instance(context);
129 predefClassDef = make.ClassDef(
130 make.Modifiers(PUBLIC),
131 syms.predefClass.name, null, null, null, null);
132 predefClassDef.sym = syms.predefClass;
133 todo = Todo.instance(context);
134 fileManager = context.get(JavaFileManager.class);
135 }
137 /** A hashtable mapping classes and packages to the environments current
138 * at the points of their definitions.
139 */
140 Map<TypeSymbol,Env<AttrContext>> typeEnvs =
141 new HashMap<TypeSymbol,Env<AttrContext>>();
143 /** Accessor for typeEnvs
144 */
145 public Env<AttrContext> getEnv(TypeSymbol sym) {
146 return typeEnvs.get(sym);
147 }
149 public Env<AttrContext> getClassEnv(TypeSymbol sym) {
150 Env<AttrContext> localEnv = getEnv(sym);
151 Env<AttrContext> lintEnv = localEnv;
152 while (lintEnv.info.lint == null)
153 lintEnv = lintEnv.next;
154 localEnv.info.lint = lintEnv.info.lint.augment(sym.attributes_field, sym.flags());
155 return localEnv;
156 }
158 /** The queue of all classes that might still need to be completed;
159 * saved and initialized by main().
160 */
161 ListBuffer<ClassSymbol> uncompleted;
163 /** A dummy class to serve as enclClass for toplevel environments.
164 */
165 private JCClassDecl predefClassDef;
167 /* ************************************************************************
168 * environment construction
169 *************************************************************************/
172 /** Create a fresh environment for class bodies.
173 * This will create a fresh scope for local symbols of a class, referred
174 * to by the environments info.scope field.
175 * This scope will contain
176 * - symbols for this and super
177 * - symbols for any type parameters
178 * In addition, it serves as an anchor for scopes of methods and initializers
179 * which are nested in this scope via Scope.dup().
180 * This scope should not be confused with the members scope of a class.
181 *
182 * @param tree The class definition.
183 * @param env The environment current outside of the class definition.
184 */
185 public Env<AttrContext> classEnv(JCClassDecl tree, Env<AttrContext> env) {
186 Env<AttrContext> localEnv =
187 env.dup(tree, env.info.dup(new Scope(tree.sym)));
188 localEnv.enclClass = tree;
189 localEnv.outer = env;
190 localEnv.info.isSelfCall = false;
191 localEnv.info.lint = null; // leave this to be filled in by Attr,
192 // when annotations have been processed
193 return localEnv;
194 }
196 /** Create a fresh environment for toplevels.
197 * @param tree The toplevel tree.
198 */
199 Env<AttrContext> topLevelEnv(JCCompilationUnit tree) {
200 Env<AttrContext> localEnv = new Env<AttrContext>(tree, new AttrContext());
201 localEnv.toplevel = tree;
202 localEnv.enclClass = predefClassDef;
203 tree.namedImportScope = new Scope.ImportScope(tree.packge);
204 tree.starImportScope = new Scope.ImportScope(tree.packge);
205 localEnv.info.scope = tree.namedImportScope;
206 localEnv.info.lint = lint;
207 return localEnv;
208 }
210 public Env<AttrContext> getTopLevelEnv(JCCompilationUnit tree) {
211 Env<AttrContext> localEnv = new Env<AttrContext>(tree, new AttrContext());
212 localEnv.toplevel = tree;
213 localEnv.enclClass = predefClassDef;
214 localEnv.info.scope = tree.namedImportScope;
215 localEnv.info.lint = lint;
216 return localEnv;
217 }
219 /** The scope in which a member definition in environment env is to be entered
220 * This is usually the environment's scope, except for class environments,
221 * where the local scope is for type variables, and the this and super symbol
222 * only, and members go into the class member scope.
223 */
224 Scope enterScope(Env<AttrContext> env) {
225 return (env.tree.getTag() == JCTree.CLASSDEF)
226 ? ((JCClassDecl) env.tree).sym.members_field
227 : env.info.scope;
228 }
230 /* ************************************************************************
231 * Visitor methods for phase 1: class enter
232 *************************************************************************/
234 /** Visitor argument: the current environment.
235 */
236 protected Env<AttrContext> env;
238 /** Visitor result: the computed type.
239 */
240 Type result;
242 /** Visitor method: enter all classes in given tree, catching any
243 * completion failure exceptions. Return the tree's type.
244 *
245 * @param tree The tree to be visited.
246 * @param env The environment visitor argument.
247 */
248 Type classEnter(JCTree tree, Env<AttrContext> env) {
249 Env<AttrContext> prevEnv = this.env;
250 try {
251 this.env = env;
252 tree.accept(this);
253 return result;
254 } catch (CompletionFailure ex) {
255 return chk.completionError(tree.pos(), ex);
256 } finally {
257 this.env = prevEnv;
258 }
259 }
261 /** Visitor method: enter classes of a list of trees, returning a list of types.
262 */
263 <T extends JCTree> List<Type> classEnter(List<T> trees, Env<AttrContext> env) {
264 ListBuffer<Type> ts = new ListBuffer<Type>();
265 for (List<T> l = trees; l.nonEmpty(); l = l.tail) {
266 Type t = classEnter(l.head, env);
267 if (t != null)
268 ts.append(t);
269 }
270 return ts.toList();
271 }
273 @Override
274 public void visitTopLevel(JCCompilationUnit tree) {
275 JavaFileObject prev = log.useSource(tree.sourcefile);
276 boolean addEnv = false;
277 boolean isPkgInfo = tree.sourcefile.isNameCompatible("package-info",
278 JavaFileObject.Kind.SOURCE);
279 if (tree.pid != null) {
280 tree.packge = reader.enterPackage(TreeInfo.fullName(tree.pid));
281 if (tree.packageAnnotations.nonEmpty()) {
282 if (isPkgInfo) {
283 addEnv = true;
284 } else {
285 log.error(tree.packageAnnotations.head.pos(),
286 "pkg.annotations.sb.in.package-info.java");
287 }
288 }
289 } else {
290 tree.packge = syms.unnamedPackage;
291 }
292 tree.packge.complete(); // Find all classes in package.
293 Env<AttrContext> topEnv = topLevelEnv(tree);
295 // Save environment of package-info.java file.
296 if (isPkgInfo) {
297 Env<AttrContext> env0 = typeEnvs.get(tree.packge);
298 if (env0 == null) {
299 typeEnvs.put(tree.packge, topEnv);
300 } else {
301 JCCompilationUnit tree0 = env0.toplevel;
302 if (!fileManager.isSameFile(tree.sourcefile, tree0.sourcefile)) {
303 log.warning(tree.pid != null ? tree.pid.pos()
304 : null,
305 "pkg-info.already.seen",
306 tree.packge);
307 if (addEnv || (tree0.packageAnnotations.isEmpty() &&
308 tree.docComments != null &&
309 tree.docComments.get(tree) != null)) {
310 typeEnvs.put(tree.packge, topEnv);
311 }
312 }
313 }
315 for (Symbol q = tree.packge; q != null && q.kind == PCK; q = q.owner)
316 q.flags_field |= EXISTS;
318 Name name = names.package_info;
319 ClassSymbol c = reader.enterClass(name, tree.packge);
320 c.flatname = names.fromString(tree.packge + "." + name);
321 c.sourcefile = tree.sourcefile;
322 c.completer = null;
323 c.members_field = new Scope(c);
324 tree.packge.package_info = c;
325 }
326 classEnter(tree.defs, topEnv);
327 if (addEnv) {
328 todo.append(topEnv);
329 }
330 log.useSource(prev);
331 result = null;
332 }
334 @Override
335 public void visitClassDef(JCClassDecl tree) {
336 Symbol owner = env.info.scope.owner;
337 Scope enclScope = enterScope(env);
338 ClassSymbol c;
339 if (owner.kind == PCK) {
340 // We are seeing a toplevel class.
341 PackageSymbol packge = (PackageSymbol)owner;
342 for (Symbol q = packge; q != null && q.kind == PCK; q = q.owner)
343 q.flags_field |= EXISTS;
344 c = reader.enterClass(tree.name, packge);
345 packge.members().enterIfAbsent(c);
346 if ((tree.mods.flags & PUBLIC) != 0 && !classNameMatchesFileName(c, env)) {
347 log.error(tree.pos(),
348 "class.public.should.be.in.file", tree.name);
349 }
350 } else {
351 if (!tree.name.isEmpty() &&
352 !chk.checkUniqueClassName(tree.pos(), tree.name, enclScope)) {
353 result = null;
354 return;
355 }
356 if (owner.kind == TYP) {
357 // We are seeing a member class.
358 c = reader.enterClass(tree.name, (TypeSymbol)owner);
359 if ((owner.flags_field & INTERFACE) != 0) {
360 tree.mods.flags |= PUBLIC | STATIC;
361 }
362 } else {
363 // We are seeing a local class.
364 c = reader.defineClass(tree.name, owner);
365 c.flatname = chk.localClassName(c);
366 if (!c.name.isEmpty())
367 chk.checkTransparentClass(tree.pos(), c, env.info.scope);
368 }
369 }
370 tree.sym = c;
372 // Enter class into `compiled' table and enclosing scope.
373 if (chk.compiled.get(c.flatname) != null) {
374 duplicateClass(tree.pos(), c);
375 result = types.createErrorType(tree.name, (TypeSymbol)owner, Type.noType);
376 tree.sym = (ClassSymbol)result.tsym;
377 return;
378 }
379 chk.compiled.put(c.flatname, c);
380 enclScope.enter(c);
382 // Set up an environment for class block and store in `typeEnvs'
383 // table, to be retrieved later in memberEnter and attribution.
384 Env<AttrContext> localEnv = classEnv(tree, env);
385 typeEnvs.put(c, localEnv);
387 // Fill out class fields.
388 c.completer = memberEnter;
389 c.flags_field = chk.checkFlags(tree.pos(), tree.mods.flags, c, tree);
390 c.sourcefile = env.toplevel.sourcefile;
391 c.members_field = new Scope(c);
393 ClassType ct = (ClassType)c.type;
394 if (owner.kind != PCK && (c.flags_field & STATIC) == 0) {
395 // We are seeing a local or inner class.
396 // Set outer_field of this class to closest enclosing class
397 // which contains this class in a non-static context
398 // (its "enclosing instance class"), provided such a class exists.
399 Symbol owner1 = owner;
400 while ((owner1.kind & (VAR | MTH)) != 0 &&
401 (owner1.flags_field & STATIC) == 0) {
402 owner1 = owner1.owner;
403 }
404 if (owner1.kind == TYP) {
405 ct.setEnclosingType(owner1.type);
406 }
407 }
409 // Enter type parameters.
410 ct.typarams_field = classEnter(tree.typarams, localEnv);
412 // Add non-local class to uncompleted, to make sure it will be
413 // completed later.
414 if (!c.isLocal() && uncompleted != null) uncompleted.append(c);
415 // System.err.println("entering " + c.fullname + " in " + c.owner);//DEBUG
417 // Recursively enter all member classes.
418 classEnter(tree.defs, localEnv);
420 result = c.type;
421 }
422 //where
423 /** Does class have the same name as the file it appears in?
424 */
425 private static boolean classNameMatchesFileName(ClassSymbol c,
426 Env<AttrContext> env) {
427 return env.toplevel.sourcefile.isNameCompatible(c.name.toString(),
428 JavaFileObject.Kind.SOURCE);
429 }
431 /** Complain about a duplicate class. */
432 protected void duplicateClass(DiagnosticPosition pos, ClassSymbol c) {
433 log.error(pos, "duplicate.class", c.fullname);
434 }
436 /** Class enter visitor method for type parameters.
437 * Enter a symbol for type parameter in local scope, after checking that it
438 * is unique.
439 */
440 @Override
441 public void visitTypeParameter(JCTypeParameter tree) {
442 TypeVar a = (tree.type != null)
443 ? (TypeVar)tree.type
444 : new TypeVar(tree.name, env.info.scope.owner, syms.botType);
445 tree.type = a;
446 if (chk.checkUnique(tree.pos(), a.tsym, env.info.scope)) {
447 env.info.scope.enter(a.tsym);
448 }
449 result = a;
450 }
452 /** Default class enter visitor method: do nothing.
453 */
454 @Override
455 public void visitTree(JCTree tree) {
456 result = null;
457 }
459 /** Main method: enter all classes in a list of toplevel trees.
460 * @param trees The list of trees to be processed.
461 */
462 public void main(List<JCCompilationUnit> trees) {
463 complete(trees, null);
464 }
466 /** Main method: enter one class from a list of toplevel trees and
467 * place the rest on uncompleted for later processing.
468 * @param trees The list of trees to be processed.
469 * @param c The class symbol to be processed.
470 */
471 public void complete(List<JCCompilationUnit> trees, ClassSymbol c) {
472 annotate.enterStart();
473 ListBuffer<ClassSymbol> prevUncompleted = uncompleted;
474 if (memberEnter.completionEnabled) uncompleted = new ListBuffer<ClassSymbol>();
476 try {
477 // enter all classes, and construct uncompleted list
478 classEnter(trees, null);
480 // complete all uncompleted classes in memberEnter
481 if (memberEnter.completionEnabled) {
482 while (uncompleted.nonEmpty()) {
483 ClassSymbol clazz = uncompleted.next();
484 if (c == null || c == clazz || prevUncompleted == null)
485 clazz.complete();
486 else
487 // defer
488 prevUncompleted.append(clazz);
489 }
491 // if there remain any unimported toplevels (these must have
492 // no classes at all), process their import statements as well.
493 for (JCCompilationUnit tree : trees) {
494 if (tree.starImportScope.elems == null) {
495 JavaFileObject prev = log.useSource(tree.sourcefile);
496 Env<AttrContext> topEnv = topLevelEnv(tree);
497 memberEnter.memberEnter(tree, topEnv);
498 log.useSource(prev);
499 }
500 }
501 }
502 } finally {
503 uncompleted = prevUncompleted;
504 annotate.enterDone();
505 }
506 }
507 }