8000 SI-3772 Fix detection of term-owned companions · scala/scala@f1a4d59 · GitHub
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SI-3772 Fix detection of term-owned companions
Companion detection consults the scopes of enclosing Contexts during typechecking to avoid the cycles that would ensue if we had to look at into the info of enclosing class symbols. For example, this used to typecheck: object CC { val outer = 42 } if ("".isEmpty) { case class CC(c: Int) CC.outer } This logic was not suitably hardened to find companions in exactly the same nesting level. After fixing this problem, a similar problem in `Namer::inCurrentScope` could be solved to be more selective about synthesizing a companion object. In particular, if a manually defined companion trails after the case class, don't create an addiotional synthetic comanpanion object.
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8 files changed

+85
-25
lines changed

8 files changed

+85
-25
lines changed

‎src/compiler/scala/tools/nsc/typechecker/Namers.scala

Lines changed: 13 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -220,7 +220,12 @@ trait Namers extends MethodSynthesis {
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private def inCurrentScope(m: Symbol): Boolean = {
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if (owner.isClass) owner == m.owner
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else m.owner.isClass && context.scope == m.owner.info.decls
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else {
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context.scope.lookupSymbolEntry(m) match {
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case null => false
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case entry => entry.owner eq context.scope
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}
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}
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}
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/** Enter symbol int 8000 o context's scope and return symbol itself */
@@ -1923,10 +1928,13 @@ trait Namers extends MethodSynthesis {
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// use the lower-level scan through the current Context as a fall back.
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if (!currentRun.compiles(owner)) owner.initialize
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original.companionSymbol orElse {
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ctx.lookup(original.name.companionName, owner).suchThat(sym =>
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(original.isTerm || sym.hasModuleFlag) &&
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(sym isCoDefinedWith original)
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)
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var c = ctx
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var companion: Symbol = NoSymbol
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while (c != NoContext && companion == NoSymbol) {
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companion = c.scope.lookupCompanion(original)
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c = c.outer
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}
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companion
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}
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}
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‎src/reflect/scala/reflect/internal/Scopes.scala

Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -282,6 +282,30 @@ trait Scopes extends api.Scopes { self: SymbolTable =>
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}
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}
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final def lookupSymbolEntry(sym: Symbol): ScopeEntry = {
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var e = lookupEntry(sym.name)
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while (e ne null) {
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if (e.sym == sym) return e
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e = lookupNextEntry(e)
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}
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null
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}
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final def lookupCompanion(original: Symbol): Symbol = {
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lookupSymbolEntry(original) match {
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case null =>
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case entry if entry.sym == original =>
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entry.owner.lookupAllEntries(original.name.companionName)
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.filter(_.owner eq entry.owner)
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.filter(x => original.isTerm || x.sym.hasModuleFlag).toList match {
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case only :: Nil => return only.sym
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case _ =>
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}
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case _ =>
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}
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NoSymbol
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}
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/** lookup a symbol entry matching given name.
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* @note from Martin: I believe this is a hotspot or will be one
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* in future versions of the type system. I have reverted the previous

‎test/files/neg/t3772.check

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,7 @@
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t3772.scala:7: error: value inner is not a member of object CC
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CC.inner
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^
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t3772.scala:14: error: value outer is not a member of object CC
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CC.outer
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^
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two errors found

‎test/files/neg/t3772.scala

Lines changed: 17 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,17 @@
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class Test {
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def m = {
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case class CC(c: Int)
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if ("".isEmpty) {
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object CC { def inner = 42}
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}
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CC.inner
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}
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def n = {
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object CC { val outer = 42 }
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if ("".isEmpty) {
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case class CC(c: Int)
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CC(0).c
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CC.outer
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}
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}
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}

‎test/files/neg/t8002-nested-scope.check

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,4 @@
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t8002-nested-scope.scala:8: error: method x in class C cannot be accessed in C
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new C().x
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^
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one error found

‎test/files/neg/t8002-nested-scope.scala

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,12 @@
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class C {
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def foo = {
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class C { private def x = 0 }
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{
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val a = 0
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object C {
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new C().x
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}
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}
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}
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}

‎test/files/pos/t3772.scala

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
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class Test {
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def m = {
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case class C(c: Int)
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object C { def xxx = true}
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C(42).c
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C.xxx
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}
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}

‎test/files/pos/t8002-nested-scope.scala

Lines changed: 0 additions & 20 deletions
This file was deleted.

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