Test for -release:8 consistency between host JDK

Author: arixmkii

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -182,6 +182,7 @@ class CompilationTests {
       compileFile("tests/neg-custom-args/i7314.scala", defaultOptions.and("-Xfatal-warnings", "-source", "future")),
       compileFile("tests/neg-custom-args/feature-shadowing.scala", defaultOptions.and("-Xfatal-warnings", "-feature")),
       compileDir("tests/neg-custom-args/hidden-type-errors", defaultOptions.and("-explain")),
+      compileFile("tests/neg-custom-args/jdk-9-app.scala", defaultOptions.and("-release:8")),
     ).checkExpectedErrors()
   }
 

tests/neg-custom-args/jdk-9-app.check

@@ -0,0 +1,6 @@
+-- [E006] Not Found Error: tests/neg-custom-args/jdk-9-app.scala:4:10 --------------------------------------------------
+4 |  println(ProcessHandle.current().pid()) // error: not found
+  |          ^^^^^^^^^^^^^
+  |          Not found: ProcessHandle
+
+longer explanation available when compiling with `-explain`

tests/neg-custom-args/jdk-9-app.scala

@@ -0,0 +1,5 @@
+import java.lang.ProcessHandle
+
+object Jdk9App extends App {
+  println(ProcessHandle.current().pid()) // error: not found
+}