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author | Martin Odersky <odersky@gmail.com> | 2016-07-15 13:06:22 +0200 |
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committer | Martin Odersky <odersky@gmail.com> | 2016-07-15 13:08:59 +0200 |
commit | b93ffa5cc46533cb8a74d19fbc46e0287cedecdd (patch) | |
tree | 0d8466c7b7c85c25be252535af84e62e86e4ba58 | |
parent | 4bec4fa6d6c1844abab4e4e64ea7763e17ca30bf (diff) | |
download | dotty-b93ffa5cc46533cb8a74d19fbc46e0287cedecdd.tar.gz dotty-b93ffa5cc46533cb8a74d19fbc46e0287cedecdd.tar.bz2 dotty-b93ffa5cc46533cb8a74d19fbc46e0287cedecdd.zip |
Fix #1386: Reduce double def errors
Use additional disambiguation criteria before raising a double def error.
See for context: #1240.
Review by @darkdimius
-rw-r--r-- | src/dotty/tools/dotc/core/Denotations.scala | 30 |
1 files changed, 24 insertions, 6 deletions
diff --git a/src/dotty/tools/dotc/core/Denotations.scala b/src/dotty/tools/dotc/core/Denotations.scala index 5ce8cbcd8..e23e66b95 100644 --- a/src/dotty/tools/dotc/core/Denotations.scala +++ b/src/dotty/tools/dotc/core/Denotations.scala @@ -292,24 +292,41 @@ object Denotations { val sym1 = denot1.symbol val sym2 = denot2.symbol - if (isDoubleDef(sym1, sym2)) doubleDefError(denot1, denot2, pre) - val sym2Accessible = sym2.isAccessibleFrom(pre) + /** Does `sym1` come before `sym2` in the linearization of `pre`? */ def precedes(sym1: Symbol, sym2: Symbol) = { def precedesIn(bcs: List[ClassSymbol]): Boolean = bcs match { case bc :: bcs1 => (sym1 eq bc) || !(sym2 eq bc) && precedesIn(bcs1) case Nil => true } - sym1.derivesFrom(sym2) || - !sym2.derivesFrom(sym1) && precedesIn(pre.baseClasses) + (sym1 ne sym2) && + (sym1.derivesFrom(sym2) || + !sym2.derivesFrom(sym1) && precedesIn(pre.baseClasses)) } - /** Preference according to partial pre-order (isConcrete, precedes) */ + /** Establish a partial order "preference" order between symbols. + * Give preference to `sym1` over `sym2` if one of the following + * conditions holds, in decreasing order of weight: + * 1. sym1 is concrete and sym2 is abstract + * 2. The owner of sym1 comes before the owner of sym2 in the linearization + * of the type of the prefix `pre`. + * 3. The access boundary of sym2 is properly contained in the access + * boundary of sym1. For protected access, we count the enclosing + * package as access boundary. + * 4. sym1 a method but sym2 is not. + * The aim of these criteria is to give some disambiguation on access which + * - does not depend on textual order or other arbitrary choices + * - minimizes raising of doubleDef errors + */ def preferSym(sym1: Symbol, sym2: Symbol) = sym1.eq(sym2) || sym1.isAsConcrete(sym2) && - (!sym2.isAsConcrete(sym1) || precedes(sym1.owner, sym2.owner)) + (!sym2.isAsConcrete(sym1) || + precedes(sym1.owner, sym2.owner) || + sym2.accessBoundary(sym2.enclosingPackageClass) + .isProperlyContainedIn(sym1.accessBoundary(sym1.enclosingPackageClass)) || + sym1.is(Method) && !sym2.is(Method)) /** Sym preference provided types also override */ def prefer(sym1: Symbol, sym2: Symbol, info1: Type, info2: Type) = @@ -321,6 +338,7 @@ object Denotations { if (sym1Accessible && prefer(sym1, sym2, info1, info2)) denot1 else if (sym1Accessible && sym2.exists && !sym2Accessible) denot1 else if (sym2Accessible && sym1.exists && !sym1Accessible) denot2 + else if (isDoubleDef(sym1, sym2)) doubleDefError(denot1, denot2, pre) else { val sym = if (!sym1.exists) sym2 |