1.1 --- a/src/share/classes/com/sun/tools/javac/comp/Check.java Fri Aug 30 17:36:47 2013 -0700
1.2 +++ b/src/share/classes/com/sun/tools/javac/comp/Check.java Mon Sep 02 22:38:36 2013 +0100
1.3 @@ -2368,7 +2368,10 @@
1.4 //for each method m1 that is overridden (directly or indirectly)
1.5 //by method 'sym' in 'site'...
1.6 for (Symbol m1 : types.membersClosure(site, false).getElementsByName(sym.name, cf)) {
1.7 - if (!sym.overrides(m1, site.tsym, types, false)) continue;
1.8 + if (!sym.overrides(m1, site.tsym, types, false)) {
1.9 + checkPotentiallyAmbiguousOverloads(pos, site, sym, (MethodSymbol)m1);
1.10 + continue;
1.11 + }
1.12 //...check each method m2 that is a member of 'site'
1.13 for (Symbol m2 : types.membersClosure(site, false).getElementsByName(sym.name, cf)) {
1.14 if (m2 == m1) continue;
1.15 @@ -2406,14 +2409,17 @@
1.16 for (Symbol s : types.membersClosure(site, true).getElementsByName(sym.name, cf)) {
1.17 //if (i) the signature of 'sym' is not a subsignature of m1 (seen as
1.18 //a member of 'site') and (ii) 'sym' has the same erasure as m1, issue an error
1.19 - if (!types.isSubSignature(sym.type, types.memberType(site, s), allowStrictMethodClashCheck) &&
1.20 - types.hasSameArgs(s.erasure(types), sym.erasure(types))) {
1.21 - log.error(pos,
1.22 - "name.clash.same.erasure.no.hide",
1.23 - sym, sym.location(),
1.24 - s, s.location());
1.25 - return;
1.26 - }
1.27 + if (!types.isSubSignature(sym.type, types.memberType(site, s), allowStrictMethodClashCheck)) {
1.28 + if (types.hasSameArgs(s.erasure(types), sym.erasure(types))) {
1.29 + log.error(pos,
1.30 + "name.clash.same.erasure.no.hide",
1.31 + sym, sym.location(),
1.32 + s, s.location());
1.33 + return;
1.34 + } else {
1.35 + checkPotentiallyAmbiguousOverloads(pos, site, sym, (MethodSymbol)s);
1.36 + }
1.37 + }
1.38 }
1.39 }
1.40
1.41 @@ -2496,6 +2502,62 @@
1.42 }
1.43 }
1.44
1.45 + /**
1.46 + * Report warnings for potentially ambiguous method declarations. Two declarations
1.47 + * are potentially ambiguous if they feature two unrelated functional interface
1.48 + * in same argument position (in which case, a call site passing an implicit
1.49 + * lambda would be ambiguous).
1.50 + */
1.51 + void checkPotentiallyAmbiguousOverloads(DiagnosticPosition pos, Type site,
1.52 + MethodSymbol msym1, MethodSymbol msym2) {
1.53 + if (msym1 != msym2 &&
1.54 + allowDefaultMethods &&
1.55 + lint.isEnabled(LintCategory.OVERLOADS) &&
1.56 + (msym1.flags() & POTENTIALLY_AMBIGUOUS) == 0 &&
1.57 + (msym2.flags() & POTENTIALLY_AMBIGUOUS) == 0) {
1.58 + Type mt1 = types.memberType(site, msym1);
1.59 + Type mt2 = types.memberType(site, msym2);
1.60 + //if both generic methods, adjust type variables
1.61 + if (mt1.hasTag(FORALL) && mt2.hasTag(FORALL) &&
1.62 + types.hasSameBounds((ForAll)mt1, (ForAll)mt2)) {
1.63 + mt2 = types.subst(mt2, ((ForAll)mt2).tvars, ((ForAll)mt1).tvars);
1.64 + }
1.65 + //expand varargs methods if needed
1.66 + int maxLength = Math.max(mt1.getParameterTypes().length(), mt2.getParameterTypes().length());
1.67 + List<Type> args1 = rs.adjustArgs(mt1.getParameterTypes(), msym1, maxLength, true);
1.68 + List<Type> args2 = rs.adjustArgs(mt2.getParameterTypes(), msym2, maxLength, true);
1.69 + //if arities don't match, exit
1.70 + if (args1.length() != args2.length()) return;
1.71 + boolean potentiallyAmbiguous = false;
1.72 + while (args1.nonEmpty() && args2.nonEmpty()) {
1.73 + Type s = args1.head;
1.74 + Type t = args2.head;
1.75 + if (!types.isSubtype(t, s) && !types.isSubtype(s, t)) {
1.76 + if (types.isFunctionalInterface(s) && types.isFunctionalInterface(t) &&
1.77 + types.findDescriptorType(s).getParameterTypes().length() > 0 &&
1.78 + types.findDescriptorType(s).getParameterTypes().length() ==
1.79 + types.findDescriptorType(t).getParameterTypes().length()) {
1.80 + potentiallyAmbiguous = true;
1.81 + } else {
1.82 + break;
1.83 + }
1.84 + }
1.85 + args1 = args1.tail;
1.86 + args2 = args2.tail;
1.87 + }
1.88 + if (potentiallyAmbiguous) {
1.89 + //we found two incompatible functional interfaces with same arity
1.90 + //this means a call site passing an implicit lambda would be ambigiuous
1.91 + msym1.flags_field |= POTENTIALLY_AMBIGUOUS;
1.92 + msym2.flags_field |= POTENTIALLY_AMBIGUOUS;
1.93 + log.warning(LintCategory.OVERLOADS, pos, "potentially.ambiguous.overload",
1.94 + msym1, msym1.location(),
1.95 + msym2, msym2.location());
1.96 + return;
1.97 + }
1.98 + }
1.99 + }
1.100 +
1.101 /** Report a conflict between a user symbol and a synthetic symbol.
1.102 */
1.103 private void syntheticError(DiagnosticPosition pos, Symbol sym) {
