SI-7264 Initialize owner when searching for companion.

From ClassSymbol:

    protected final def companionModule0: Symbol =
      flatOwnerInfo.decl(name.toTermName).suchThat(sym => sym.isModuleNotMethod && (sym isCoDefinedWith this))

    protected final def flatOwnerInfo: Type = {
      if (needsFlatClasses)
        info
      owner.rawInfo
    }

Note the call to `rawInfo`; in the enclosed test case, that gives
us back an uninitialized type for the module class of `Foo`, and
consequently we don't find the companion for `Foo.Values`.

This commit forces the initialization of the owning symbol if it
was compiled in a prior run.

In addition, it adds a special case to `Run#compiles` for early
initialized symbols, which start out in life with the wrong owner.
As best as I can see, that complexity stems from allowing early
initialized members *without* return types to be used as value arguments
to the super call, which in turn is needed to infer parent type arguments.
The situation is described a little further in existing comments of
`typedPrimaryConstrBody`.

This bug is essentially another case of SI-6976. See the comments in pull
request of that patch (https://github.com/scala/scala/pull/1910) for
commit archaeology that shows why we're reluctant to force the owner
info more broadly than is done in this commit.

1 files changed, 6 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index 4683fca192..0305aab844 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -1686,8 +1686,13 @@ trait Namers extends MethodSynthesis {
    *  call this method?
    */
   def companionSymbolOf(original: Symbol, ctx: Context): Symbol = {
+    val owner = original.owner
+    // SI-7264 Force the info of owners from previous compilation runs.
+    //         Doing this generally would trigger cycles; that's what we also
+    //         use the lower-level scan through the current Context as a fall back.
+    if (!currentRun.compiles(owner)) owner.initialize
     original.companionSymbol orElse {
-      ctx.lookup(original.name.companionName, original.owner).suchThat(sym =>
+      ctx.lookup(original.name.companionName, owner).suchThat(sym =>
         (original.isTerm || sym.hasModuleFlag) &&
         (sym isCoDefinedWith original)
       )