add tail call test

makefile

@@ -585,6 +585,11 @@ ifeq ($(continuations),true)
 		extra.DynamicWind
 endif
 
+ifeq ($(tails),true)
+	tail-tests = \
+		extra.Tails
+endif
+
 class-name = $(patsubst $(1)/%.class,%,$(2))
 class-names = $(foreach x,$(2),$(call class-name,$(1),$(x)))
 
@@ -617,7 +622,7 @@ test: build
 	$(library-path) /bin/sh $(test)/test.sh 2>/dev/null \
 		$(test-executable) $(mode) "$(test-flags)" \
 		$(call class-names,$(test-build),$(test-classes)) \
-		$(continuation-tests)
+		$(continuation-tests) $(tail-tests)
 
 .PHONY: tarball
 tarball:

test/extra/Tails.java

@@ -0,0 +1,49 @@
+package extra;
+
+public class Tails {
+  private static final int Limit = 1000000;
+
+  private static void expect(boolean v) {
+    if (! v) throw new RuntimeException();
+  }
+
+  private static int staticMethod(Interface i, int n) {
+    if (n < Limit) {
+      return i.interfaceMethod(n + 1);
+    } else {
+      return leafMethod(n);
+    }
+  }
+
+  private static int leafMethod(int n) {
+    expect(new Throwable().getStackTrace().length == 2);
+
+    return n;
+  }
+
+  public static void main(String[] args) {
+    expect(staticMethod(new Foo(), 0) == Limit);
+  }
+
+  private interface Interface {
+    public int interfaceMethod(int n);
+  }
+
+  private static class Foo implements Interface {
+    public int interfaceMethod(int n) {
+      if (n < Limit) {
+        return virtualMethod(n + 1, 1, 2, 3, 4, 5);
+      } else {
+        return leafMethod(n);
+      }
+    }
+
+    public int virtualMethod(int n, int a, int b, int c, int d, int e) {
+      if (n < Limit) {
+        return staticMethod(this, n + 1);
+      } else {
+        return leafMethod(n);
+      }
+    }
+  }
+}