SI-6439 Avoid spurious REPL warnings about companionship

`val m` isn't a companion of `trait m`, check the pair of
eponymous symbols are a ((class|trait), object) pair before
emitting the warning.

In order to correctly check this one a type alias is involved,
`definedSymbols` must avoid normalizing through type aliases.
AFAICT this is an improvement to the other clients of that Map,
one such power mode progression is demonstrated at the end
of the test case.

3 files changed, 90 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/interpreter/IMain.scala b/src/compiler/scala/tools/nsc/interpreter/IMain.scala
index b46d28dec3..a55f0af116 100644
--- a/src/compiler/scala/tools/nsc/interpreter/IMain.scala
+++ b/src/compiler/scala/tools/nsc/interpreter/IMain.scala
@@ -386,6 +386,7 @@ class IMain(initialSettings: Settings, protected val out: JPrintWriter) extends
       oldReq <- definedNameMap get name.companionName
       newSym <- req.definedSymbols get name
       oldSym <- oldReq.definedSymbols get name.companionName
+      if Seq(oldSym, newSym).permutations exists { case Seq(s1, s2) => s1.isClass && s2.isModule }
     } {
       afterTyper(replwarn(s"warning: previously defined $oldSym is not a companion to $newSym."))
       replwarn("Companions must be defined together; you may wish to use :paste mode for this.")
@@ -970,7 +971,7 @@ class IMain(initialSettings: Settings, protected val out: JPrintWriter) extends
     // }
     lazy val definedSymbols = (
       termNames.map(x => x -> applyToResultMember(x, x => x)) ++
-      typeNames.map(x => x -> compilerTypeOf(x).typeSymbol)
+      typeNames.map(x => x -> compilerTypeOf(x).typeSymbolDirect)
     ).toMap[Name, Symbol] withDefaultValue NoSymbol
 
     lazy val typesOfDefinedTerms = mapFrom[Name, Name, Type](termNames)(x => applyToResultMember(x, _.tpe))
diff --git a/test/files/run/t6439.check b/test/files/run/t6439.check
new file mode 100644
index 0000000000..178ea739f5
--- /dev/null
+++ b/test/files/run/t6439.check
@@ -0,0 +1,66 @@
+Type in expressions to have them evaluated.
+Type :help for more information.
+
+scala> 
+
+scala> class A
+defined class A
+
+scala> object A // warn
+defined module A
+warning: previously defined class A is not a companion to object A.
+Companions must be defined together; you may wish to use :paste mode for this.
+
+scala> trait B
+defined trait B
+
+scala> object B // warn
+defined module B
+warning: previously defined trait B is not a companion to object B.
+Companions must be defined together; you may wish to use :paste mode for this.
+
+scala> object C
+defined module C
+
+scala> object Bippy
+defined module Bippy
+
+scala> class C // warn
+defined class C
+warning: previously defined object C is not a companion to class C.
+Companions must be defined together; you may wish to use :paste mode for this.
+
+scala> class D
+defined class D
+
+scala> def D = 0 // no warn
+D: Int
+
+scala> val D = 0 // no warn
+D: Int = 0
+
+scala> object E
+defined module E
+
+scala> var E = 0 // no warn
+E: Int = 0
+
+scala> object F
+defined module F
+
+scala> type F = Int // no warn
+defined type alias F
+
+scala> :power
+** Power User mode enabled - BEEP WHIR GYVE **
+** :phase has been set to 'typer'.          **
+** scala.tools.nsc._ has been imported      **
+** global._, definitions._ also imported    **
+** Try  :help, :vals, power.<tab>           **
+
+scala> intp("F") // this now works as a result of changing .typeSymbol to .typeSymbolDirect in IMain#Request#definedSymbols
+res0: $r.intp.global.Symbol = type F
+
+scala> 
+
+scala> 
diff --git a/test/files/run/t6439.scala b/test/files/run/t6439.scala
new file mode 100644
index 0000000000..70a2dbafaf
--- /dev/null
+++ b/test/files/run/t6439.scala
@@ -0,0 +1,22 @@
+import scala.tools.partest.ReplTest
+
+object Test extends ReplTest {
+  def code = """
+class A
+object A // warn
+trait B
+object B // warn
+object C
+object Bippy
+class C // warn
+class D
+def D = 0 // no warn
+val D = 0 // no warn
+object E
+var E = 0 // no warn
+object F
+type F = Int // no warn
+:power
+intp("F") // this now works as a result of changing .typeSymbol to .typeSymbolDirect in IMain#Request#definedSymbols
+             """
+}