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src/share/classes/com/sun/tools/javac/comp/Infer.java@05814303a056
src/share/classes/com/sun/tools/javac/comp/Infer.java
Mon, 24 Oct 2011 13:00:30 +0100
- author
- mcimadamore
- date
- Mon, 24 Oct 2011 13:00:30 +0100
- changeset 1114
- 05814303a056
- parent 1087
- 3a2200681d69
- child 1127
- ca49d50318dc
- permissions
- -rw-r--r--
7098660: Write better overload resolution/inference tests
Summary: Add overload/inference debug diagnostics - added test harness using annotations to check outcome of overload resolution/inference
Reviewed-by: jjg
1 /*
2 * Copyright (c) 1999, 2011, 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 com.sun.tools.javac.tree.JCTree;
29 import com.sun.tools.javac.tree.JCTree.JCTypeCast;
30 import com.sun.tools.javac.tree.TreeInfo;
31 import com.sun.tools.javac.util.*;
32 import com.sun.tools.javac.util.List;
33 import com.sun.tools.javac.code.*;
34 import com.sun.tools.javac.code.Type.*;
35 import com.sun.tools.javac.code.Type.ForAll.ConstraintKind;
36 import com.sun.tools.javac.code.Symbol.*;
37 import com.sun.tools.javac.comp.Resolve.VerboseResolutionMode;
38 import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
40 import static com.sun.tools.javac.code.TypeTags.*;
42 /** Helper class for type parameter inference, used by the attribution phase.
43 *
44 * <p><b>This is NOT part of any supported API.
45 * If you write code that depends on this, you do so at your own risk.
46 * This code and its internal interfaces are subject to change or
47 * deletion without notice.</b>
48 */
49 public class Infer {
50 protected static final Context.Key<Infer> inferKey =
51 new Context.Key<Infer>();
53 /** A value for prototypes that admit any type, including polymorphic ones. */
54 public static final Type anyPoly = new Type(NONE, null);
56 Symtab syms;
57 Types types;
58 Check chk;
59 Resolve rs;
60 Log log;
61 JCDiagnostic.Factory diags;
63 public static Infer instance(Context context) {
64 Infer instance = context.get(inferKey);
65 if (instance == null)
66 instance = new Infer(context);
67 return instance;
68 }
70 protected Infer(Context context) {
71 context.put(inferKey, this);
72 syms = Symtab.instance(context);
73 types = Types.instance(context);
74 rs = Resolve.instance(context);
75 log = Log.instance(context);
76 chk = Check.instance(context);
77 diags = JCDiagnostic.Factory.instance(context);
78 ambiguousNoInstanceException =
79 new NoInstanceException(true, diags);
80 unambiguousNoInstanceException =
81 new NoInstanceException(false, diags);
82 invalidInstanceException =
83 new InvalidInstanceException(diags);
85 }
87 public static class InferenceException extends Resolve.InapplicableMethodException {
88 private static final long serialVersionUID = 0;
90 InferenceException(JCDiagnostic.Factory diags) {
91 super(diags);
92 }
93 }
95 public static class NoInstanceException extends InferenceException {
96 private static final long serialVersionUID = 1;
98 boolean isAmbiguous; // exist several incomparable best instances?
100 NoInstanceException(boolean isAmbiguous, JCDiagnostic.Factory diags) {
101 super(diags);
102 this.isAmbiguous = isAmbiguous;
103 }
104 }
106 public static class InvalidInstanceException extends InferenceException {
107 private static final long serialVersionUID = 2;
109 InvalidInstanceException(JCDiagnostic.Factory diags) {
110 super(diags);
111 }
112 }
114 private final NoInstanceException ambiguousNoInstanceException;
115 private final NoInstanceException unambiguousNoInstanceException;
116 private final InvalidInstanceException invalidInstanceException;
118 /***************************************************************************
119 * Auxiliary type values and classes
120 ***************************************************************************/
122 /** A mapping that turns type variables into undetermined type variables.
123 */
124 Mapping fromTypeVarFun = new Mapping("fromTypeVarFun") {
125 public Type apply(Type t) {
126 if (t.tag == TYPEVAR) return new UndetVar(t);
127 else return t.map(this);
128 }
129 };
131 /** A mapping that returns its type argument with every UndetVar replaced
132 * by its `inst' field. Throws a NoInstanceException
133 * if this not possible because an `inst' field is null.
134 * Note: mutually referring undertvars will be left uninstantiated
135 * (that is, they will be replaced by the underlying type-variable).
136 */
138 Mapping getInstFun = new Mapping("getInstFun") {
139 public Type apply(Type t) {
140 switch (t.tag) {
141 case UNKNOWN:
142 throw ambiguousNoInstanceException
143 .setMessage("undetermined.type");
144 case UNDETVAR:
145 UndetVar that = (UndetVar) t;
146 if (that.inst == null)
147 throw ambiguousNoInstanceException
148 .setMessage("type.variable.has.undetermined.type",
149 that.qtype);
150 return isConstraintCyclic(that) ?
151 that.qtype :
152 apply(that.inst);
153 default:
154 return t.map(this);
155 }
156 }
158 private boolean isConstraintCyclic(UndetVar uv) {
159 Types.UnaryVisitor<Boolean> constraintScanner =
160 new Types.UnaryVisitor<Boolean>() {
162 List<Type> seen = List.nil();
164 Boolean visit(List<Type> ts) {
165 for (Type t : ts) {
166 if (visit(t)) return true;
167 }
168 return false;
169 }
171 public Boolean visitType(Type t, Void ignored) {
172 return false;
173 }
175 @Override
176 public Boolean visitClassType(ClassType t, Void ignored) {
177 if (t.isCompound()) {
178 return visit(types.supertype(t)) ||
179 visit(types.interfaces(t));
180 } else {
181 return visit(t.getTypeArguments());
182 }
183 }
184 @Override
185 public Boolean visitWildcardType(WildcardType t, Void ignored) {
186 return visit(t.type);
187 }
189 @Override
190 public Boolean visitUndetVar(UndetVar t, Void ignored) {
191 if (seen.contains(t)) {
192 return true;
193 } else {
194 seen = seen.prepend(t);
195 return visit(t.inst);
196 }
197 }
198 };
199 return constraintScanner.visit(uv);
200 }
201 };
203 /***************************************************************************
204 * Mini/Maximization of UndetVars
205 ***************************************************************************/
207 /** Instantiate undetermined type variable to its minimal upper bound.
208 * Throw a NoInstanceException if this not possible.
209 */
210 void maximizeInst(UndetVar that, Warner warn) throws NoInstanceException {
211 List<Type> hibounds = Type.filter(that.hibounds, errorFilter);
212 if (that.inst == null) {
213 if (hibounds.isEmpty())
214 that.inst = syms.objectType;
215 else if (hibounds.tail.isEmpty())
216 that.inst = hibounds.head;
217 else
218 that.inst = types.glb(hibounds);
219 }
220 if (that.inst == null ||
221 that.inst.isErroneous())
222 throw ambiguousNoInstanceException
223 .setMessage("no.unique.maximal.instance.exists",
224 that.qtype, hibounds);
225 }
226 //where
227 private boolean isSubClass(Type t, final List<Type> ts) {
228 t = t.baseType();
229 if (t.tag == TYPEVAR) {
230 List<Type> bounds = types.getBounds((TypeVar)t);
231 for (Type s : ts) {
232 if (!types.isSameType(t, s.baseType())) {
233 for (Type bound : bounds) {
234 if (!isSubClass(bound, List.of(s.baseType())))
235 return false;
236 }
237 }
238 }
239 } else {
240 for (Type s : ts) {
241 if (!t.tsym.isSubClass(s.baseType().tsym, types))
242 return false;
243 }
244 }
245 return true;
246 }
248 private Filter<Type> errorFilter = new Filter<Type>() {
249 @Override
250 public boolean accepts(Type t) {
251 return !t.isErroneous();
252 }
253 };
255 /** Instantiate undetermined type variable to the lub of all its lower bounds.
256 * Throw a NoInstanceException if this not possible.
257 */
258 void minimizeInst(UndetVar that, Warner warn) throws NoInstanceException {
259 List<Type> lobounds = Type.filter(that.lobounds, errorFilter);
260 if (that.inst == null) {
261 if (lobounds.isEmpty())
262 that.inst = syms.botType;
263 else if (lobounds.tail.isEmpty())
264 that.inst = lobounds.head.isPrimitive() ? syms.errType : lobounds.head;
265 else {
266 that.inst = types.lub(lobounds);
267 }
268 if (that.inst == null || that.inst.tag == ERROR)
269 throw ambiguousNoInstanceException
270 .setMessage("no.unique.minimal.instance.exists",
271 that.qtype, lobounds);
272 // VGJ: sort of inlined maximizeInst() below. Adding
273 // bounds can cause lobounds that are above hibounds.
274 List<Type> hibounds = Type.filter(that.hibounds, errorFilter);
275 Type hb = null;
276 if (hibounds.isEmpty())
277 hb = syms.objectType;
278 else if (hibounds.tail.isEmpty())
279 hb = hibounds.head;
280 else
281 hb = types.glb(hibounds);
282 if (hb == null ||
283 hb.isErroneous())
284 throw ambiguousNoInstanceException
285 .setMessage("incompatible.upper.bounds",
286 that.qtype, hibounds);
287 }
288 }
290 /***************************************************************************
291 * Exported Methods
292 ***************************************************************************/
294 /** Try to instantiate expression type `that' to given type `to'.
295 * If a maximal instantiation exists which makes this type
296 * a subtype of type `to', return the instantiated type.
297 * If no instantiation exists, or if several incomparable
298 * best instantiations exist throw a NoInstanceException.
299 */
300 public Type instantiateExpr(ForAll that,
301 Type to,
302 Warner warn) throws InferenceException {
303 List<Type> undetvars = Type.map(that.tvars, fromTypeVarFun);
304 for (List<Type> l = undetvars; l.nonEmpty(); l = l.tail) {
305 UndetVar uv = (UndetVar) l.head;
306 TypeVar tv = (TypeVar)uv.qtype;
307 ListBuffer<Type> hibounds = new ListBuffer<Type>();
308 for (Type t : that.getConstraints(tv, ConstraintKind.EXTENDS)) {
309 hibounds.append(types.subst(t, that.tvars, undetvars));
310 }
312 List<Type> inst = that.getConstraints(tv, ConstraintKind.EQUAL);
313 if (inst.nonEmpty() && inst.head.tag != BOT) {
314 uv.inst = inst.head;
315 }
316 uv.hibounds = hibounds.toList();
317 }
318 Type qtype1 = types.subst(that.qtype, that.tvars, undetvars);
319 if (!types.isSubtype(qtype1,
320 qtype1.tag == UNDETVAR ? types.boxedTypeOrType(to) : to)) {
321 throw unambiguousNoInstanceException
322 .setMessage("infer.no.conforming.instance.exists",
323 that.tvars, that.qtype, to);
324 }
325 for (List<Type> l = undetvars; l.nonEmpty(); l = l.tail)
326 maximizeInst((UndetVar) l.head, warn);
327 // System.out.println(" = " + qtype1.map(getInstFun));//DEBUG
329 // check bounds
330 List<Type> targs = Type.map(undetvars, getInstFun);
331 if (Type.containsAny(targs, that.tvars)) {
332 //replace uninferred type-vars
333 targs = types.subst(targs,
334 that.tvars,
335 instaniateAsUninferredVars(undetvars, that.tvars));
336 }
337 return chk.checkType(warn.pos(), that.inst(targs, types), to);
338 }
339 //where
340 private List<Type> instaniateAsUninferredVars(List<Type> undetvars, List<Type> tvars) {
341 ListBuffer<Type> new_targs = ListBuffer.lb();
342 //step 1 - create syntethic captured vars
343 for (Type t : undetvars) {
344 UndetVar uv = (UndetVar)t;
345 Type newArg = new CapturedType(t.tsym.name, t.tsym, uv.inst, syms.botType, null);
346 new_targs = new_targs.append(newArg);
347 }
348 //step 2 - replace synthetic vars in their bounds
349 for (Type t : new_targs.toList()) {
350 CapturedType ct = (CapturedType)t;
351 ct.bound = types.subst(ct.bound, tvars, new_targs.toList());
352 WildcardType wt = new WildcardType(ct.bound, BoundKind.EXTENDS, syms.boundClass);
353 ct.wildcard = wt;
354 }
355 return new_targs.toList();
356 }
358 /** Instantiate method type `mt' by finding instantiations of
359 * `tvars' so that method can be applied to `argtypes'.
360 */
361 public Type instantiateMethod(final Env<AttrContext> env,
362 List<Type> tvars,
363 MethodType mt,
364 final Symbol msym,
365 final List<Type> argtypes,
366 final boolean allowBoxing,
367 final boolean useVarargs,
368 final Warner warn) throws InferenceException {
369 //-System.err.println("instantiateMethod(" + tvars + ", " + mt + ", " + argtypes + ")"); //DEBUG
370 List<Type> undetvars = Type.map(tvars, fromTypeVarFun);
371 List<Type> formals = mt.argtypes;
372 //need to capture exactly once - otherwise subsequent
373 //applicability checks might fail
374 final List<Type> capturedArgs = types.capture(argtypes);
375 List<Type> actuals = capturedArgs;
376 List<Type> actualsNoCapture = argtypes;
377 // instantiate all polymorphic argument types and
378 // set up lower bounds constraints for undetvars
379 Type varargsFormal = useVarargs ? formals.last() : null;
380 if (varargsFormal == null &&
381 actuals.size() != formals.size()) {
382 throw unambiguousNoInstanceException
383 .setMessage("infer.arg.length.mismatch");
384 }
385 while (actuals.nonEmpty() && formals.head != varargsFormal) {
386 Type formal = formals.head;
387 Type actual = actuals.head.baseType();
388 Type actualNoCapture = actualsNoCapture.head.baseType();
389 if (actual.tag == FORALL)
390 actual = instantiateArg((ForAll)actual, formal, tvars, warn);
391 Type undetFormal = types.subst(formal, tvars, undetvars);
392 boolean works = allowBoxing
393 ? types.isConvertible(actual, undetFormal, warn)
394 : types.isSubtypeUnchecked(actual, undetFormal, warn);
395 if (!works) {
396 throw unambiguousNoInstanceException
397 .setMessage("infer.no.conforming.assignment.exists",
398 tvars, actualNoCapture, formal);
399 }
400 formals = formals.tail;
401 actuals = actuals.tail;
402 actualsNoCapture = actualsNoCapture.tail;
403 }
405 if (formals.head != varargsFormal) // not enough args
406 throw unambiguousNoInstanceException.setMessage("infer.arg.length.mismatch");
408 // for varargs arguments as well
409 if (useVarargs) {
410 Type elemType = types.elemtype(varargsFormal);
411 Type elemUndet = types.subst(elemType, tvars, undetvars);
412 while (actuals.nonEmpty()) {
413 Type actual = actuals.head.baseType();
414 Type actualNoCapture = actualsNoCapture.head.baseType();
415 if (actual.tag == FORALL)
416 actual = instantiateArg((ForAll)actual, elemType, tvars, warn);
417 boolean works = types.isConvertible(actual, elemUndet, warn);
418 if (!works) {
419 throw unambiguousNoInstanceException
420 .setMessage("infer.no.conforming.assignment.exists",
421 tvars, actualNoCapture, elemType);
422 }
423 actuals = actuals.tail;
424 actualsNoCapture = actualsNoCapture.tail;
425 }
426 }
428 // minimize as yet undetermined type variables
429 for (Type t : undetvars)
430 minimizeInst((UndetVar) t, warn);
432 /** Type variables instantiated to bottom */
433 ListBuffer<Type> restvars = new ListBuffer<Type>();
435 /** Undet vars instantiated to bottom */
436 final ListBuffer<Type> restundet = new ListBuffer<Type>();
438 /** Instantiated types or TypeVars if under-constrained */
439 ListBuffer<Type> insttypes = new ListBuffer<Type>();
441 /** Instantiated types or UndetVars if under-constrained */
442 ListBuffer<Type> undettypes = new ListBuffer<Type>();
444 for (Type t : undetvars) {
445 UndetVar uv = (UndetVar)t;
446 if (uv.inst.tag == BOT) {
447 restvars.append(uv.qtype);
448 restundet.append(uv);
449 insttypes.append(uv.qtype);
450 undettypes.append(uv);
451 uv.inst = null;
452 } else {
453 insttypes.append(uv.inst);
454 undettypes.append(uv.inst);
455 }
456 }
457 checkWithinBounds(tvars, undettypes.toList(), warn);
459 mt = (MethodType)types.subst(mt, tvars, insttypes.toList());
461 if (!restvars.isEmpty()) {
462 // if there are uninstantiated variables,
463 // quantify result type with them
464 final List<Type> inferredTypes = insttypes.toList();
465 final List<Type> all_tvars = tvars; //this is the wrong tvars
466 return new UninferredMethodType(env.tree.pos(), msym, mt, restvars.toList()) {
467 @Override
468 List<Type> getConstraints(TypeVar tv, ConstraintKind ck) {
469 for (Type t : restundet.toList()) {
470 UndetVar uv = (UndetVar)t;
471 if (uv.qtype == tv) {
472 switch (ck) {
473 case EXTENDS: return uv.hibounds.appendList(types.subst(types.getBounds(tv), all_tvars, inferredTypes));
474 case SUPER: return uv.lobounds;
475 case EQUAL: return uv.inst != null ? List.of(uv.inst) : List.<Type>nil();
476 }
477 }
478 }
479 return List.nil();
480 }
481 @Override
482 void check(List<Type> inferred, Types types) throws NoInstanceException {
483 // check that actuals conform to inferred formals
484 checkArgumentsAcceptable(env, capturedArgs, getParameterTypes(), allowBoxing, useVarargs, warn);
485 // check that inferred bounds conform to their bounds
486 checkWithinBounds(all_tvars,
487 types.subst(inferredTypes, tvars, inferred), warn);
488 if (useVarargs) {
489 chk.checkVararg(env.tree.pos(), getParameterTypes(), msym);
490 }
491 }};
492 }
493 else {
494 // check that actuals conform to inferred formals
495 checkArgumentsAcceptable(env, capturedArgs, mt.getParameterTypes(), allowBoxing, useVarargs, warn);
496 // return instantiated version of method type
497 return mt;
498 }
499 }
500 //where
502 /**
503 * A delegated type representing a partially uninferred method type.
504 * The return type of a partially uninferred method type is a ForAll
505 * type - when the return type is instantiated (see Infer.instantiateExpr)
506 * the underlying method type is also updated.
507 */
508 abstract class UninferredMethodType extends DelegatedType {
510 final List<Type> tvars;
511 final Symbol msym;
512 final DiagnosticPosition pos;
514 public UninferredMethodType(DiagnosticPosition pos, Symbol msym, MethodType mtype, List<Type> tvars) {
515 super(METHOD, new MethodType(mtype.argtypes, null, mtype.thrown, mtype.tsym));
516 this.tvars = tvars;
517 this.msym = msym;
518 this.pos = pos;
519 asMethodType().restype = new UninferredReturnType(tvars, mtype.restype);
520 }
522 @Override
523 public MethodType asMethodType() {
524 return qtype.asMethodType();
525 }
527 @Override
528 public Type map(Mapping f) {
529 return qtype.map(f);
530 }
532 void instantiateReturnType(Type restype, List<Type> inferred, Types types) throws NoInstanceException {
533 //update method type with newly inferred type-arguments
534 qtype = new MethodType(types.subst(getParameterTypes(), tvars, inferred),
535 restype,
536 types.subst(UninferredMethodType.this.getThrownTypes(), tvars, inferred),
537 UninferredMethodType.this.qtype.tsym);
538 check(inferred, types);
539 }
541 abstract void check(List<Type> inferred, Types types) throws NoInstanceException;
543 abstract List<Type> getConstraints(TypeVar tv, ConstraintKind ck);
545 class UninferredReturnType extends ForAll {
546 public UninferredReturnType(List<Type> tvars, Type restype) {
547 super(tvars, restype);
548 }
549 @Override
550 public Type inst(List<Type> actuals, Types types) {
551 Type newRestype = super.inst(actuals, types);
552 instantiateReturnType(newRestype, actuals, types);
553 if (rs.verboseResolutionMode.contains(VerboseResolutionMode.DEFERRED_INST)) {
554 log.note(pos, "deferred.method.inst", msym, UninferredMethodType.this.qtype, newRestype);
555 }
556 return newRestype;
557 }
558 @Override
559 public List<Type> getConstraints(TypeVar tv, ConstraintKind ck) {
560 return UninferredMethodType.this.getConstraints(tv, ck);
561 }
562 }
563 }
565 private void checkArgumentsAcceptable(Env<AttrContext> env, List<Type> actuals, List<Type> formals,
566 boolean allowBoxing, boolean useVarargs, Warner warn) {
567 try {
568 rs.checkRawArgumentsAcceptable(env, actuals, formals,
569 allowBoxing, useVarargs, warn);
570 }
571 catch (Resolve.InapplicableMethodException ex) {
572 // inferred method is not applicable
573 throw invalidInstanceException.setMessage(ex.getDiagnostic());
574 }
575 }
577 /** Try to instantiate argument type `that' to given type `to'.
578 * If this fails, try to insantiate `that' to `to' where
579 * every occurrence of a type variable in `tvars' is replaced
580 * by an unknown type.
581 */
582 private Type instantiateArg(ForAll that,
583 Type to,
584 List<Type> tvars,
585 Warner warn) throws InferenceException {
586 List<Type> targs;
587 try {
588 return instantiateExpr(that, to, warn);
589 } catch (NoInstanceException ex) {
590 Type to1 = to;
591 for (List<Type> l = tvars; l.nonEmpty(); l = l.tail)
592 to1 = types.subst(to1, List.of(l.head), List.of(syms.unknownType));
593 return instantiateExpr(that, to1, warn);
594 }
595 }
597 /** check that type parameters are within their bounds.
598 */
599 void checkWithinBounds(List<Type> tvars,
600 List<Type> arguments,
601 Warner warn)
602 throws InvalidInstanceException {
603 for (List<Type> tvs = tvars, args = arguments;
604 tvs.nonEmpty();
605 tvs = tvs.tail, args = args.tail) {
606 if (args.head instanceof UndetVar ||
607 tvars.head.getUpperBound().isErroneous()) continue;
608 List<Type> bounds = types.subst(types.getBounds((TypeVar)tvs.head), tvars, arguments);
609 if (!types.isSubtypeUnchecked(args.head, bounds, warn))
610 throw invalidInstanceException
611 .setMessage("inferred.do.not.conform.to.bounds",
612 args.head, bounds);
613 }
614 }
616 /**
617 * Compute a synthetic method type corresponding to the requested polymorphic
618 * method signature. The target return type is computed from the immediately
619 * enclosing scope surrounding the polymorphic-signature call.
620 */
621 Type instantiatePolymorphicSignatureInstance(Env<AttrContext> env, Type site,
622 Name name,
623 MethodSymbol spMethod, // sig. poly. method or null if none
624 List<Type> argtypes) {
625 final Type restype;
627 //The return type for a polymorphic signature call is computed from
628 //the enclosing tree E, as follows: if E is a cast, then use the
629 //target type of the cast expression as a return type; if E is an
630 //expression statement, the return type is 'void' - otherwise the
631 //return type is simply 'Object'. A correctness check ensures that
632 //env.next refers to the lexically enclosing environment in which
633 //the polymorphic signature call environment is nested.
635 switch (env.next.tree.getTag()) {
636 case JCTree.TYPECAST:
637 JCTypeCast castTree = (JCTypeCast)env.next.tree;
638 restype = (TreeInfo.skipParens(castTree.expr) == env.tree) ?
639 castTree.clazz.type :
640 syms.objectType;
641 break;
642 case JCTree.EXEC:
643 JCTree.JCExpressionStatement execTree =
644 (JCTree.JCExpressionStatement)env.next.tree;
645 restype = (TreeInfo.skipParens(execTree.expr) == env.tree) ?
646 syms.voidType :
647 syms.objectType;
648 break;
649 default:
650 restype = syms.objectType;
651 }
653 List<Type> paramtypes = Type.map(argtypes, implicitArgType);
654 List<Type> exType = spMethod != null ?
655 spMethod.getThrownTypes() :
656 List.of(syms.throwableType); // make it throw all exceptions
658 MethodType mtype = new MethodType(paramtypes,
659 restype,
660 exType,
661 syms.methodClass);
662 return mtype;
663 }
664 //where
665 Mapping implicitArgType = new Mapping ("implicitArgType") {
666 public Type apply(Type t) {
667 t = types.erasure(t);
668 if (t.tag == BOT)
669 // nulls type as the marker type Null (which has no instances)
670 // infer as java.lang.Void for now
671 t = types.boxedClass(syms.voidType).type;
672 return t;
673 }
674 };
675 }
