Refactor tests and fix isGlobal

Author: odersky

compiler/src/dotty/tools/dotc/typer/CheckCaptures.scala

@@ -124,6 +124,7 @@ class CheckCaptures extends RefineTypes:
               val isGlobal = ref match
                 case ref: TypeRef => ref.isRootCapability
                 case ref: TermRef => ref.prefix != NoPrefix && ref.symbol.hasAnnotation(defn.AbilityAnnot)
+                case _ => false
               val what = if ref.isRootCapability then "universal" else "global"
               if isGlobal then
                 val notAllowed = i" is not allowed to capture the $what capability $ref"

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

@@ -33,13 +33,13 @@ class CompilationTests {
       compileFilesInDir("tests/pos-special/sourcepath/outer", defaultOptions.and("-sourcepath", "tests/pos-special/sourcepath")),
       compileFile("tests/pos-special/sourcepath/outer/nested/Test4.scala", defaultOptions.and("-sourcepath", "tests/pos-special/sourcepath")),
       compileFilesInDir("tests/pos-special/fatal-warnings", defaultOptions.and("-Xfatal-warnings", "-deprecation", "-feature")),
-      compileFilesInDir("tests/pos-special/captures", defaultOptions.and("-Ycc")),
       compileFile("tests/pos-special/avoid-warn-deprecation.scala", defaultOptions.and("-Xfatal-warnings", "-feature")),
       compileFilesInDir("tests/pos-special/spec-t5545", defaultOptions),
       compileFilesInDir("tests/pos-special/strawman-collections", allowDeepSubtypes),
       compileFilesInDir("tests/pos-special/isInstanceOf", allowDeepSubtypes.and("-Xfatal-warnings")),
       compileFilesInDir("tests/new", defaultOptions),
       compileFilesInDir("tests/pos-scala2", scala2CompatMode),
+      compileFilesInDir("tests/pos-custom-args/captures", defaultOptions.and("-Ycc")),
       compileFilesInDir("tests/pos-custom-args/erased", defaultOptions.and("-language:experimental.erasedDefinitions")),
       compileFilesInDir("tests/pos", defaultOptions.and("-Ysafe-init")),
       compileFilesInDir("tests/pos-deep-subtype", allowDeepSubtypes),

tests/neg-custom-args/captures/io.scala

@@ -0,0 +1,21 @@
+sealed trait IO:
+  def puts(msg: Any): Unit = println(msg)
+
+def test1 =
+  val IO : IO retains * = new IO {}
+  def foo = IO.puts("hello")
+  val x : () => Unit = () => foo  // error: Found: (() => Unit) retains IO; Required: () => Unit
+
+def test2 =
+  val IO : IO retains * = new IO {}
+  def puts(msg: Any, io: IO retains *) = println(msg)
+  def foo() = puts("hello", IO)
+  val x : () => Unit = () => foo()  // error: Found: (() => Unit) retains IO; Required: () => Unit
+
+type Capability[T] = T retains *
+
+def test3 =
+  val IO : Capability[IO] = new IO {}
+  def puts(msg: Any, io: Capability[IO]) = println(msg)
+  def foo() = puts("hello", IO)
+  val x : () => Unit = () => foo()  // error: Found: (() => Unit) retains IO; Required: () => Unit