reflection no longer uses enteringPhase and friends

Mentioned methods mutate the global `atPhaseStack` variable, which can
easily lead to imbalances and, ultimately, to the empty stack error.

Luckily for us, there's only one dummy phase, SomePhase, which is used
by runtime reflection, so there is absolutely zero need to invoke atPhase
in non-compiler reflexive universes.

The cleanest solution would be to override `atPhase` for runtime reflection,
but it's @inline final, so I didn't want to pay performance penalties for
something that's used three times in runtime reflection (during unpickling, in
reflection-specific completers and in `Symbol.typeParams/unsafeTypeParams`).

Therefore I added overrideable analogues of `atPhase` and `atPhaseNotLaterThan`
which are called from the aforementioned code shared between the compiler and
runtime reflection. I also had to duplicate the code of `Symbol.XXXtypeParams`
(only in SynchronizedSymbols, not in normal Symbols) again due to those
methods being very performance-sensitive.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/reflect/scala/reflect/internal/Symbols.scala b/src/reflect/scala/reflect/internal/Symbols.scala
index 123e213f50..868913c82f 100644
--- a/src/reflect/scala/reflect/internal/Symbols.scala
+++ b/src/reflect/scala/reflect/internal/Symbols.scala
@@ -1565,6 +1565,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      *  assumption: if a type starts out as monomorphic, it will not acquire
      *  type parameters later.
      */
+    // NOTE: overridden in SynchronizedSymbols with the code copy/pasted
+    // don't forget to modify the code over there if you modify this method
     def unsafeTypeParams: List[Symbol] =
       if (isMonomorphicType) Nil
       else enteringPhase(unsafeTypeParamPhase)(rawInfo.typeParams)
@@ -1573,6 +1575,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
      *  assumption: if a type starts out as monomorphic, it will not acquire
      *  type parameters later.
      */
+    // NOTE: overridden in SynchronizedSymbols with the code copy/pasted
+    // don't forget to modify the code over there if you modify this method
     def typeParams: List[Symbol] =
       if (isMonomorphicType) Nil
       else {