Fix error handling in dart2js async-await

tests/language/async_throw_in_catch_test.dart

+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:async";
+import "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
+
+class Tracer {
+  final String expected;
+  final String name;
+  int counter = 0;
+
+  Tracer(this.expected, [this.name]);
+
+  void trace(msg) {
+    if (name != null) {
+      print("Tracing $name: $msg");
+    }
+    Expect.equals(expected[counter], msg);
+    counter++;
+  }
+
+  void done() {
+    Expect.equals(expected.length, counter, "Received too few traces");
+  }
+}
+
+foo1(Tracer tracer) async {

[floitsch, 2015/02/17 12:40:58]

You could consider removing the "async" in the /// forceAwait case too.
(shouldn't change anything, though).

[sigurdm, 2015/02/17 14:19:49]

I want to check that the async rewrite works properly, even though it leaves
some parts untranslated

+  try {
+    tracer.trace("a");
+    // This await  forces dart2js to rewrite the try into a state machine

[floitsch, 2015/02/17 12:40:58]

nit nit. 2 spaces after "await".

[sigurdm, 2015/02/17 14:19:49]

Done.

+    // instead of relying on the existing structure.
+    await new Future.value(3); /// forceAwait: ok
+    tracer.trace("b");
+    throw "Error";
+  } catch (error) {
+    tracer.trace("c");
+    Expect.equals("Error", error);
+    throw "Error2";
+    tracer.trace("d");
+  } finally {
+    tracer.trace("e");
+  }
+  tracer.trace("f");
+}
+
+foo2(Tracer tracer) async {
+  try {
+    tracer.trace("a");
+    await new Future.value(3); /// forceAwait: continued
+    tracer.trace("b");
+    throw "Error";
+    tracer.trace("c");
+  } catch (error) {
+    tracer.trace("d");
+    Expect.equals("Error", error);
+    await new Future.error("Error2");
+  } finally {
+    tracer.trace("e");
+  }
+  tracer.trace("f");
+}
+
+foo3(Tracer tracer) async {
+  try {
+    tracer.trace("a");
+    await new Future.value(3); /// forceAwait: continued
+    tracer.trace("b");
+    throw "Error";
+    tracer.trace("c");
+  } catch (error) {
+    Expect.equals("Error", error);
+    tracer.trace("d");
+    return;
+  } finally {
+    tracer.trace("e");
+  }
+  tracer.trace("f");
+}
+
+foo4(Tracer tracer) async {
+  try {
+    try {
+      await new Future.value(3);

[floitsch, 2015/02/17 12:40:58]

/// forceAwait: continue ?

[sigurdm, 2015/02/17 14:19:49]

Done.

+      tracer.trace("a");
+      throw "Error";
+    } catch(error) {
+      tracer.trace("b");
+      Expect.equals("Error", error);
+      throw "Error2";
+    }
+  } catch(error) {
+    Expect.equals("Error2", error);
+    tracer.trace("c");
+  }
+  tracer.trace("d");
+
+}
+
+foo5(Tracer tracer) async {
+  try {
+    tracer.trace("a");
+    try {
+      await new Future.value(3); /// forceAwait: continued
+      tracer.trace("b");
+      throw "Error";
+    } catch(error) {
+      tracer.trace("c");
+      Expect.equals("Error", error);
+      throw "Error2";
+    }
+  } finally {
+    tracer.trace("d");
+  }
+  tracer.trace("e");
+
+}
+
+foo6(Tracer tracer) async {
+  try {
+    try {
+      await new Future.value(3); /// forceAwait: continued
+      tracer.trace("a");
+      throw "Error";
+    } catch(error) {
+      tracer.trace("b");
+      Expect.equals("Error", error);
+      throw "Error2";
+    } finally {
+      tracer.trace("c");
+      throw "Error3";

[floitsch, 2015/02/17 12:40:58]

Please add a few tests, where the "finally" does a "return". (I see throws, but
no returns).
('continue' would be nice too, but there are at least some 'break'-in-finally
tests)

[sigurdm, 2015/02/17 14:19:49]

Done.

+    }
+  } catch(error) {
+    tracer.trace("d");
+    Expect.equals("Error3", error);
+  }
+  tracer.trace("e");
+}
+
+foo7(Tracer tracer) async {
+  try {
+    try {
+      await new Future.value(3); /// forceAwait: continued
+      tracer.trace("a");
+      throw "Error";
+    } catch(error) {
+      Expect.equals("Error", error);
+      tracer.trace("b");
+      throw "Error2";
+    } finally {
+      tracer.trace("c");
+      throw "Error3";
+    }
+  } finally {
+    tracer.trace("d");
+  }
+  tracer.trace("e");
+}
+
+foo8(Tracer tracer) async {
+  try {
+    try {
+      await new Future.value(3); /// forceAwait: continued
+      tracer.trace("a");
+      throw "Error";
+    } catch(error) {
+      Expect.equals("Error", error);
+      tracer.trace("b");
+      return;
+    } finally {
+      tracer.trace("c");
+      throw "Error3";
+    }
+  } finally {
+    tracer.trace("d");
+  }
+  tracer.trace("e");
+}
+
+foo9(Tracer tracer) async {
+  try {
+    while(true) {
+      try {
+        await new Future.value(3); /// forceAwait: continued
+        tracer.trace("a");
+        throw "Error";
+      } catch(error) {
+        Expect.equals("Error", error);
+        tracer.trace("b");
+        return;
+      } finally {
+        tracer.trace("c");
+        break;
+      }
+      tracer.trace("d");
+    }
+  } finally {
+    tracer.trace("e");
+  }
+  tracer.trace("f");
+}
+
+foo10(Tracer tracer) async {

[floitsch, 2015/02/17 12:40:58]

does the same as foo9.

[sigurdm, 2015/02/17 14:19:49]

Removed

+  try {
+    while(true) {
+      try {
+        await new Future.value(3); /// forceAwait: continued
+        tracer.trace("a");
+        throw "Error";
+      } catch(error) {
+        Expect.equals("Error", error);
+        tracer.trace("b");
+        return;
+      } finally {
+        tracer.trace("c");
+        break;
+      }
+      tracer.trace("d");
+    }
+  } finally {
+    tracer.trace("e");
+  }
+  tracer.trace("f");
+}
+
+foo11(Tracer tracer) async {
+  try {
+    bool firstTime = true;
+    while(true) {
+      tracer.trace("a");
+      if (firstTime) {
+        try {
+          await new Future.value(3); /// forceAwait: continued
+          tracer.trace("b");
+          throw "Error";
+        } catch(error) {
+          Expect.equals("Error", error);
+          tracer.trace("c");
+          firstTime = false;
+          continue;
+        } finally {
+          tracer.trace("d");
+        }
+      } else {
+        tracer.trace("e");
+        return;
+      }
+    }
+  } finally {
+    tracer.trace("f");
+  }
+  tracer.trace("g");
+}
+
+foo12(Tracer tracer) async {
+  try {
+    bool firstTime = true;
+    while(true) {
+      tracer.trace("a");
+      if (firstTime) {
+        try {
+          await new Future.value(3); /// forceAwait: continued
+          tracer.trace("b");
+          throw "Error";
+        } catch(error) {
+          Expect.equals("Error", error);
+          tracer.trace("c");
+          firstTime = false;
+          continue;
+        } finally {
+          tracer.trace("d");
+          break;
+        }
+      } else {
+        tracer.trace("e");
+        return;
+      }
+    }
+  } finally {
+    tracer.trace("f");
+  }
+  tracer.trace("g");
+}
+
+foo13(Tracer tracer) async {
+  try {
+    try {
+      tracer.trace("a");
+      return;
+    } catch (error) {
+      tracer.trace("b");
+    } finally {
+      tracer.trace("c");
+      try {
+        try {
+          await new Future.value(3);  /// forceAwait: continued
+          tracer.trace("d");
+          throw "Error";
+        } finally {
+          tracer.trace("e");
+        }
+      } finally {
+        tracer.trace("f");
+      }
+    }
+  } finally {
+    tracer.trace("g");
+  }
+  tracer.trace("h");
+}
+
+foo14(Tracer tracer) async {
+  try {
+    try {
+      tracer.trace("a");
+      throw "Error";
+    } catch (error) {
+      tracer.trace("b");
+      try {
+        await new Future.value(3);  /// forceAwait: continued
+        throw "Error2";
+      } catch(error) {
+        tracer.trace("c");
+      } finally {
+        tracer.trace("d");
+      }
+      tracer.trace("e");
+      throw "Error3";
+    } finally {
+      tracer.trace("f");
+    }
+  } finally {
+    tracer.trace("g");
+  }
+  tracer.trace("h");
+}
+
+test() async {
+  Tracer tracer = new Tracer("abce");
+  try {

[floitsch, 2015/02/17 12:40:58]

You could avoid a lot of the boilerplate:

runTest(String expected, String expectedError, fun) async {
  Tracer tracer = new Tracer(expected);
  try {
    await fun(tracer);
  } catch(e) {
    Expect.equals(expectedError, e);
    tracer.add("X");
  }
  tracer.done();
}

[sigurdm, 2015/02/17 14:19:49]

Done.

+    await foo1(tracer);
+  } catch (e) {
+    Expect.equals("Error2", e);

[floitsch, 2015/02/17 12:40:58]

You should trace the catching.

[sigurdm, 2015/02/17 14:19:49]

Done.

+  }
+  tracer.done();
+ 
+  tracer = new Tracer("abde");
+  try {
+    await foo2(tracer);
+  } catch (e) {
+    Expect.equals("Error2", e);
+  }
+  tracer.done();
+ 
+  tracer = new Tracer("abde");
+  await foo3(tracer);
+  tracer.done();
+ 
+  tracer = new Tracer("abcd");
+  var x = foo4(tracer);
+  await x;
+  print("foo4 done");
+  tracer.done();
+ 
+  tracer = new Tracer("abcd");
+  try {
+    await foo5(tracer);
+  } catch (e) {
+    Expect.equals("Error2", e);
+  }
+  tracer.done();
+ 
+  tracer = new Tracer("abcde");
+  await foo6(tracer);
+  tracer.done();
+ 
+  tracer = new Tracer("abcd");
+  try {
+    await foo7(tracer);
+  } catch (e) {
+    Expect.equals("Error3", e);
+  }
+  tracer.done();
+ 
+  tracer = new Tracer("abcd");
+  try {
+    await foo8(tracer);
+  } catch (e) {
+    Expect.equals("Error3", e);
+  }
+  tracer.done();
+ 
+  tracer = new Tracer("abcef");
+  await foo9(tracer);
+  tracer.done();
+ 
+  tracer = new Tracer("abcef");
+  await foo10(tracer);
+  tracer.done();
+ 
+  tracer = new Tracer("abcdaef");
+  await foo11(tracer);
+  tracer.done();
+ 
+  tracer = new Tracer("abcdfg");
+  await foo12(tracer);
+  tracer.done();
+ 
+  tracer = new Tracer("acdefg");
+  try {
+    await foo13(tracer);
+  } catch (e) {
+    Expect.equals("Error", e);
+  }
+  tracer.done();
+ 
+  tracer = new Tracer("abcdefg", "foo14");
+  try {
+    await foo14(tracer);
+  } catch (e) {
+    Expect.equals("Error3", e);
+  }
+  tracer.done();
+}
+
+void main() {
+  asyncTest(test);
+}