Reuse the same compiler instance for all tests in a JUnit class

Note that JUnit creates a new instance of the test class for running
each test method. So the compiler instance is added to the companion.
However, the JVM would quickly run out of memory when running multiple
tests, as the compilers cannot be GCd. So we make it a `var`, and set
it to null when a class is done. For that we use JUnit's `@AfterClass`
which is required to be on a static method. Therefore we add a Java
class with such a static method that we can extend from Scala.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/reflect/scala/reflect/internal/SymbolTable.scala b/src/reflect/scala/reflect/internal/SymbolTable.scala
index 01e4cdf367..ef63078f90 100644
--- a/src/reflect/scala/reflect/internal/SymbolTable.scala
+++ b/src/reflect/scala/reflect/internal/SymbolTable.scala
@@ -355,6 +355,14 @@ abstract class SymbolTable extends macros.Universe
       cache
     }
 
+    /**
+     * Removes a cache from the per-run caches. This is useful for testing: it allows running the
+     * compiler and then inspect the state of a cache.
+     */
+    def unrecordCache[T <: Clearable](cache: T): Unit = {
+      caches = caches.filterNot(_.get eq cache)
+    }
+
     def clearAll() = {
       debuglog("Clearing " + caches.size + " caches.")
       caches foreach (ref => Option(ref.get).foreach(_.clear))