[vm] Make async transform resilient in context of invalid type and never type of iterables

The CFE can invoke transformations despite having compile-time errors.
The async transform was crashing the compiler if it hits for-in
iterables that have an invalid type or never type.

In case of an invalid type, the program has a compile-time error and
won't be able to run propertly. So we'll replace the entire for-in with
an invalid expression statement if the iterable is an invalid
expression.

In case of a never type, the program should compile fine, which this CL
also fixes.

This makes the newly added tests no longer result in DartkCrash but
rather in a compile-time error (invalid expression) or runtime-error
(never type).

Closes dart-lang/sdk#45014

Change-Id: Ic50f68400b67b57dd4a2c0a125b08f0f3e0d8dd6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/188463
Commit-Queue: Johnni Winther <[email protected]>
Reviewed-by: Johnni Winther <[email protected]>

Author: johnniwinther

pkg/front_end/testcases/general/async_method_with_invalid_type.dart

@@ -1,8 +1,12 @@
 // Copyright (c) 2020, 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.md file.
+
 // @dart=2.9
+
 foo() async {
   Bar x;
   for (dynamic y in x.z) {}
-}
+}
+
+main() {}

pkg/front_end/testcases/general/async_method_with_invalid_type.dart.textual_outline.expect

@@ -1,2 +1,3 @@
 // @dart = 2.9
 foo() async {}
+main() {}

pkg/front_end/testcases/general/async_method_with_invalid_type.dart.textual_outline_modelled.expect

@@ -1,2 +1,3 @@
 // @dart = 2.9
 foo() async {}
+main() {}

pkg/front_end/testcases/general/async_method_with_invalid_type.dart.weak.expect

@@ -2,7 +2,7 @@ library;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/async_method_with_invalid_type.dart:6:3: Error: 'Bar' isn't a type.
+// pkg/front_end/testcases/general/async_method_with_invalid_type.dart:8:3: Error: 'Bar' isn't a type.
 //   Bar x;
 //   ^^^
 //
@@ -13,3 +13,4 @@ static method foo() → dynamic async {
   for (dynamic y in x.z) {
   }
 }
+static method main() → dynamic {}

pkg/front_end/testcases/general/async_method_with_invalid_type.dart.weak.outline.expect

@@ -3,3 +3,5 @@ import self as self;
 
 static method foo() → dynamic async 
   ;
+static method main() → dynamic
+  ;

pkg/front_end/testcases/general/async_method_with_invalid_type.dart.weak.transformed.expect

@@ -0,0 +1,46 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/async_method_with_invalid_type.dart:8:3: Error: 'Bar' isn't a type.
+//   Bar x;
+//   ^^^
+//
+import self as self;
+import "dart:async" as asy;
+import "dart:core" as core;
+
+static method foo() → dynamic /* originally async */ {
+  final asy::_Future<dynamic>* :async_future = new asy::_Future::•<dynamic>();
+  core::bool* :is_sync = false;
+  FutureOr<dynamic>* :return_value;
+  (dynamic) →* dynamic :async_op_then;
+  (core::Object*, core::StackTrace*) →* dynamic :async_op_error;
+  core::int* :await_jump_var = 0;
+  dynamic :await_ctx_var;
+  function :async_op([dynamic :result, dynamic :exception, dynamic :stack_trace]) → dynamic yielding 
+    try {
+      #L1:
+      {
+        invalid-type x;
+        {
+          core::Iterator<invalid-type>* :sync-for-iterator = x.z.{core::Iterable::iterator};
+          for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
+            dynamic y = :sync-for-iterator.{core::Iterator::current};
+            {}
+          }
+        }
+      }
+      asy::_completeOnAsyncReturn(:async_future, :return_value, :is_sync);
+      return;
+    }
+    on dynamic catch(dynamic exception, core::StackTrace* stack_trace) {
+      asy::_completeOnAsyncError(:async_future, exception, stack_trace, :is_sync);
+    }
+  :async_op_then = asy::_asyncThenWrapperHelper(:async_op);
+  :async_op_error = asy::_asyncErrorWrapperHelper(:async_op);
+  :async_op.call();
+  :is_sync = true;
+  return :async_future;
+}
+static method main() → dynamic {}

pkg/front_end/testcases/general/invalid_cast.dart

@@ -1,7 +1,9 @@
 // Copyright (c) 2017, 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.
+
 // @dart=2.9
+
 class C {
   C();
   factory C.fact() => null;

pkg/front_end/testcases/general/invalid_cast.dart.weak.expect

@@ -2,60 +2,60 @@ library;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/invalid_cast.dart:20:25: Error: The list literal type 'List<Object>' isn't of expected type 'List<int>'.
+// pkg/front_end/testcases/general/invalid_cast.dart:22:25: Error: The list literal type 'List<Object>' isn't of expected type 'List<int>'.
 //  - 'List' is from 'dart:core'.
 //  - 'Object' is from 'dart:core'.
 // Change the type of the list literal or the context in which it is used.
 //   List<int> a = <Object>[];
 //                         ^
 //
-// pkg/front_end/testcases/general/invalid_cast.dart:21:40: Error: The map literal type 'Map<Object, String>' isn't of expected type 'Map<int, String>'.
+// pkg/front_end/testcases/general/invalid_cast.dart:23:40: Error: The map literal type 'Map<Object, String>' isn't of expected type 'Map<int, String>'.
 //  - 'Map' is from 'dart:core'.
 //  - 'Object' is from 'dart:core'.
 // Change the type of the map literal or the context in which it is used.
 //   Map<int, String> b = <Object, String>{};
 //                                        ^
 //
-// pkg/front_end/testcases/general/invalid_cast.dart:22:37: Error: The map literal type 'Map<int, Object>' isn't of expected type 'Map<int, String>'.
+// pkg/front_end/testcases/general/invalid_cast.dart:24:37: Error: The map literal type 'Map<int, Object>' isn't of expected type 'Map<int, String>'.
 //  - 'Map' is from 'dart:core'.
 //  - 'Object' is from 'dart:core'.
 // Change the type of the map literal or the context in which it is used.
 //   Map<int, String> c = <int, Object>{};
 //                                     ^
 //
-// pkg/front_end/testcases/general/invalid_cast.dart:23:28: Error: The function expression type 'int Function(int)' isn't of expected type 'int Function(Object)'.
+// pkg/front_end/testcases/general/invalid_cast.dart:25:28: Error: The function expression type 'int Function(int)' isn't of expected type 'int Function(Object)'.
 //  - 'Object' is from 'dart:core'.
 // Change the type of the function expression or the context in which it is used.
 //   int Function(Object) d = (int i) => i;
 //                            ^
 //
-// pkg/front_end/testcases/general/invalid_cast.dart:26:13: Error: The constructor returns type 'C' that isn't of expected type 'D'.
+// pkg/front_end/testcases/general/invalid_cast.dart:28:13: Error: The constructor returns type 'C' that isn't of expected type 'D'.
 //  - 'C' is from 'pkg/front_end/testcases/general/invalid_cast.dart'.
 //  - 'D' is from 'pkg/front_end/testcases/general/invalid_cast.dart'.
 // Change the type of the object being constructed or the context in which it is used.
 //   D g = new C.nonFact();
 //             ^
 //
-// pkg/front_end/testcases/general/invalid_cast.dart:27:13: Error: The constructor returns type 'C' that isn't of expected type 'D'.
+// pkg/front_end/testcases/general/invalid_cast.dart:29:13: Error: The constructor returns type 'C' that isn't of expected type 'D'.
 //  - 'C' is from 'pkg/front_end/testcases/general/invalid_cast.dart'.
 //  - 'D' is from 'pkg/front_end/testcases/general/invalid_cast.dart'.
 // Change the type of the object being constructed or the context in which it is used.
 //   D h = new C.nonFact2();
 //             ^
 //
-// pkg/front_end/testcases/general/invalid_cast.dart:28:31: Error: The static method has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
+// pkg/front_end/testcases/general/invalid_cast.dart:30:31: Error: The static method has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
 //  - 'Object' is from 'dart:core'.
 // Change the type of the method or the context in which it is used.
 //   void Function(Object) i = C.staticFunction;
 //                               ^
 //
-// pkg/front_end/testcases/general/invalid_cast.dart:29:29: Error: The top level function has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
+// pkg/front_end/testcases/general/invalid_cast.dart:31:29: Error: The top level function has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
 //  - 'Object' is from 'dart:core'.
 // Change the type of the function or the context in which it is used.
 //   void Function(Object) j = topLevelFunction;
 //                             ^
 //
-// pkg/front_end/testcases/general/invalid_cast.dart:30:29: Error: The local function has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
+// pkg/front_end/testcases/general/invalid_cast.dart:32:29: Error: The local function has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
 //  - 'Object' is from 'dart:core'.
 // Change the type of the function or the context in which it is used.
 //   void Function(Object) k = localFunction;
@@ -99,54 +99,54 @@ class D extends self::C {
 static method topLevelFunction(core::int* i) → void {}
 static method bad() → dynamic {
   function localFunction(core::int* i) → void {}
-  core::List<core::int*>* a = let final Never* #t1 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:20:25: Error: The list literal type 'List<Object>' isn't of expected type 'List<int>'.
+  core::List<core::int*>* a = let final Never* #t1 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:22:25: Error: The list literal type 'List<Object>' isn't of expected type 'List<int>'.
  - 'List' is from 'dart:core'.
  - 'Object' is from 'dart:core'.
 Change the type of the list literal or the context in which it is used.
   List<int> a = <Object>[];
                         ^" in <core::Object*>[];
-  core::Map<core::int*, core::String*>* b = let final Never* #t2 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:21:40: Error: The map literal type 'Map<Object, String>' isn't of expected type 'Map<int, String>'.
+  core::Map<core::int*, core::String*>* b = let final Never* #t2 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:23:40: Error: The map literal type 'Map<Object, String>' isn't of expected type 'Map<int, String>'.
  - 'Map' is from 'dart:core'.
  - 'Object' is from 'dart:core'.
 Change the type of the map literal or the context in which it is used.
   Map<int, String> b = <Object, String>{};
                                        ^" in <core::Object*, core::String*>{};
-  core::Map<core::int*, core::String*>* c = let final Never* #t3 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:22:37: Error: The map literal type 'Map<int, Object>' isn't of expected type 'Map<int, String>'.
+  core::Map<core::int*, core::String*>* c = let final Never* #t3 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:24:37: Error: The map literal type 'Map<int, Object>' isn't of expected type 'Map<int, String>'.
  - 'Map' is from 'dart:core'.
  - 'Object' is from 'dart:core'.
 Change the type of the map literal or the context in which it is used.
   Map<int, String> c = <int, Object>{};
                                     ^" in <core::int*, core::Object*>{};
-  (core::Object*) →* core::int* d = let final Never* #t4 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:23:28: Error: The function expression type 'int Function(int)' isn't of expected type 'int Function(Object)'.
+  (core::Object*) →* core::int* d = let final Never* #t4 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:25:28: Error: The function expression type 'int Function(int)' isn't of expected type 'int Function(Object)'.
  - 'Object' is from 'dart:core'.
 Change the type of the function expression or the context in which it is used.
   int Function(Object) d = (int i) => i;
                            ^" in (core::int* i) → core::int* => i;
   self::D* e = self::C::fact() as{TypeError} self::D*;
   self::D* f = new self::D::•() as{TypeError} self::D*;
-  self::D* g = let final Never* #t5 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:26:13: Error: The constructor returns type 'C' that isn't of expected type 'D'.
+  self::D* g = let final Never* #t5 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:28:13: Error: The constructor returns type 'C' that isn't of expected type 'D'.
  - 'C' is from 'pkg/front_end/testcases/general/invalid_cast.dart'.
  - 'D' is from 'pkg/front_end/testcases/general/invalid_cast.dart'.
 Change the type of the object being constructed or the context in which it is used.
   D g = new C.nonFact();
             ^" in new self::C::nonFact();
-  self::D* h = let final Never* #t6 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:27:13: Error: The constructor returns type 'C' that isn't of expected type 'D'.
+  self::D* h = let final Never* #t6 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:29:13: Error: The constructor returns type 'C' that isn't of expected type 'D'.
  - 'C' is from 'pkg/front_end/testcases/general/invalid_cast.dart'.
  - 'D' is from 'pkg/front_end/testcases/general/invalid_cast.dart'.
 Change the type of the object being constructed or the context in which it is used.
   D h = new C.nonFact2();
             ^" in new self::C::nonFact2();
-  (core::Object*) →* void i = let final Never* #t7 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:28:31: Error: The static method has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
+  (core::Object*) →* void i = let final Never* #t7 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:30:31: Error: The static method has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
  - 'Object' is from 'dart:core'.
 Change the type of the method or the context in which it is used.
   void Function(Object) i = C.staticFunction;
                               ^" in #C1;
-  (core::Object*) →* void j = let final Never* #t8 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:29:29: Error: The top level function has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
+  (core::Object*) →* void j = let final Never* #t8 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:31:29: Error: The top level function has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
  - 'Object' is from 'dart:core'.
 Change the type of the function or the context in which it is used.
   void Function(Object) j = topLevelFunction;
                             ^" in #C2;
-  (core::Object*) →* void k = let final Never* #t9 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:30:29: Error: The local function has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
+  (core::Object*) →* void k = let final Never* #t9 = invalid-expression "pkg/front_end/testcases/general/invalid_cast.dart:32:29: Error: The local function has type 'void Function(int)' that isn't of expected type 'void Function(Object)'.
  - 'Object' is from 'dart:core'.
 Change the type of the function or the context in which it is used.
   void Function(Object) k = localFunction;