Towards understanding `TypeRef`'s `transformInfo`/`baseType`

By reducing excessive factoring, we can save an extraneous call
to `asSeenFrom`, and hopefully in a following commit figure out
a bigger problem with `baseType` that is causing wrong subtyping results.

This commit is a pure refactoring, save for the dropped ASF call,
which is explained below.

To motivate the following change to `relativeInfo`:

```
  private[Types] def relativeInfo = /*trace(s"relativeInfo(${safeToString}})")*/{
    if (relativeInfoPeriod != currentPeriod) {
-     val memberInfo = pre.memberInfo(sym)
-     relativeInfoCache = transformInfo(memberInfo)
+     relativeInfoCache = memberInfoInstantiated
```

Let's consolidate the two removed line in this new method:

```
def memberInfoInstantiated = transformInfo(pre.memberInfo(sym))
```

To understand what `transformInfo` does, take these helpers spread over
various `*TypeRef` traits, and consolidate them:
```
- def asSeenFromOwner(tp: Type) = tp.asSeenFrom(pre, sym.owner)

// regular type refs:
- def transformInfo(tp: Type): Type = appliedType(asSeenFromOwner(tp), args)
// for no-args type refs:
- override def transformInfo(tp: Type): Type = appliedType(asSeenFromOwner(tp), dummyArgs)
```

By removing the dynamic dispatch, we get the following method
(given `require(args0 ne Nil, this)` in `ArgsTypeRef`,
and `args eq Nil` by construction in `NoArgsTypeRef` ):

```
def transformInfo(tp: Type) =
  appliedType(tp.asSeenFrom(pre, sym.owner), if (args.isEmpty) dummyArgs else args)
```

Inlining `memberInfo`, which is defined as:

```
  def memberInfo(sym: Symbol): Type = {
      require(sym ne NoSymbol, this)
      sym.info.asSeenFrom(this, sym.owner)
    }
```

gives us:

```
def memberInfoInstantiated = transformInfo(sym.info.asSeenFrom(pre, sym.owner))
```

Inlining `transformInfo` as reworked above:

```
def memberInfoInstantiated =
  appliedType(sym.info.asSeenFrom(pre, sym.owner).asSeenFrom(pre, sym.owner),
              if (args.isEmpty) dummyArgs else args)
```

Whoops! One `asSeenFrom` should do...

```
+ final protected def memberInfoInstantiated: Type =
+   appliedType(sym.info.asSeenFrom(pre, sym.owner), if (args.isEmpty) dummyArgs else args)
```

0 files changed, 0 insertions, 0 deletions