partial fix for see #3772.

{{{
  scala> def g { case class C(); object C; }
  <console>:5: error: C is already defined as (compiler-generated) case class companion object C
         def g { case class C(); object C; }
                                        ^
}}}

review by odersky

4 files changed, 34 insertions, 21 deletions

diff --git a/src/compiler/scala/tools/nsc/symtab/Symbols.scala b/src/compiler/scala/tools/nsc/symtab/Symbols.scala
index 609dcdc829..8d02a120d3 100644
--- a/src/compiler/scala/tools/nsc/symtab/Symbols.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Symbols.scala
@@ -1253,6 +1253,8 @@ trait Symbols extends reflect.generic.Symbols { self: SymbolTable =>
 
     /** The class with the same name in the same package as this module or
      *  case class factory.
+     *  Note: does not work for classes owned by methods, see
+     *  Namers.companionClassOf
      */
     final def companionClass: Symbol = {
       if (this != NoSymbol)
@@ -1269,6 +1271,8 @@ trait Symbols extends reflect.generic.Symbols { self: SymbolTable =>
 
     /** The module or case class factory with the same name in the same
      *  package as this class.
+     *  Note: does not work for modules owned by methods, see
+     *  Namers.companionModuleOf
      */
     final def companionModule: Symbol =
       if (this.isClass && !this.isAnonymousClass && !this.isRefinementClass)
@@ -1277,6 +1281,8 @@ trait Symbols extends reflect.generic.Symbols { self: SymbolTable =>
 
     /** For a module its linked class, for a class its linked module or case
      *  factory otherwise.
+     *  Note: does not work for modules owned by methods, see
+     *  Namers.companionModuleOf / Namers.companionClassOf
      */
     final def companionSymbol: Symbol =
       if (isTerm) companionClass
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index cd5de7cb7b..235f067c95 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -288,8 +288,10 @@ trait Namers { self: Analyzer =>
      *  @return the companion object symbol.
      */
      def ensureCompanionObject(tree: ClassDef, creator: => Tree): Symbol = {
-       val m: Symbol = context.scope.lookup(tree.name.toTermName).filter(! _.isSourceMethod)
-       if (m.isModule && inCurrentScope(m) && currentRun.compiles(m)) m
+       val m = companionModuleOf(tree.symbol, context)
+       // @luc: not sure why "currentRun.compiles(m)" is needed, things breaks
+       // otherwise. documentation welcome.
+       if (m != NoSymbol && currentRun.compiles(m)) m
        else enterSyntheticSym(creator)
      }
 
@@ -1364,6 +1366,25 @@ trait Namers { self: Analyzer =>
       } else member.accessed
     } else member
 
+  /**
+   * Finds the companion module of a class symbol. Calling .companionModule
+   * does not work for classes defined inside methods.
+   */
+  def companionModuleOf(clazz: Symbol, context: Context) = {
+    var res = clazz.companionModule
+    if (res == NoSymbol)
+      res = context.lookup(clazz.name.toTermName, clazz.owner).suchThat(sym =>
+        sym.hasFlag(MODULE) && sym.isCoDefinedWith(clazz))
+    res
+  }
+
+  def companionClassOf(module: Symbol, context: Context) = {
+    var res = module.companionClass
+    if (res == NoSymbol)
+      res = context.lookup(module.name.toTypeName, module.owner).suchThat(_.isCoDefinedWith(module))
+    res
+  }
+
   /** An explanatory note to be added to error messages
    *  when there's a problem with abstract var defs */
   def varNotice(sym: Symbol): String =
diff --git a/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala b/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
index 35bb661377..e649e55c08 100644
--- a/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
@@ -506,25 +506,6 @@ trait NamesDefaults { self: Analyzer =>
   }
 
   /**
-   * Finds the companion module of a class symbol. Calling .companionModule
-   * does not work for classes defined inside methods.
-   */
-  def companionModuleOf(clazz: Symbol, context: Context) = {
-    var res = clazz.companionModule
-    if (res == NoSymbol)
-      res = context.lookup(clazz.name.toTermName, clazz.owner).suchThat(sym =>
-        sym.hasFlag(MODULE) && sym.isCoDefinedWith(clazz))
-    res
-  }
-
-  def companionClassOf(module: Symbol, context: Context) = {
-    var res = module.companionClass
-    if (res == NoSymbol)
-      res = context.lookup(module.name.toTypeName, module.owner).suchThat(_.isCoDefinedWith(module))
-    res
-  }
-
-  /**
    * Returns
    *  - the position of the parameter named `name`
    *  - optionally, if `name` is @deprecatedName, the new name
diff --git a/test/files/pos/caseClassInMethod.scala b/test/files/pos/caseClassInMethod.scala
new file mode 100644
index 0000000000..958e5dd473
--- /dev/null
+++ b/test/files/pos/caseClassInMethod.scala
@@ -0,0 +1,5 @@
+object t {
+  def f = { object C; case class C(); 1 }
+  // pending: def g = { case class D(x: Int); object D; 2 }
+  def h = { case class E(y: Int = 10); 3 }
+}