Make compile-time errors catchable

If an error happens during the compilation of a function body, an Error is thrown which can be intercepted, and ensures that finally blocks are executed before the isolate is terminated. The language spec is vague about compilation errors. A doc describing the intentions behind this CL is at https://docs.google.com/document/d/1_MWOgwJadLCQSBps0zD6Rj5dG4iP1UBuiDvTMH-WMzI/edit# Example: 1 void bad() { 2 return 5 3 } 4 5 void main(args) { 6 bad(); 7 } Before this CL: $ dart ~/tmp/e.dart 'file:///Users/hausner/tmp/e.dart': error: line 2 pos 11: semicolon expected return 5 ^ $ After this change: $ dart ~/tmp/e.dart Unhandled exception: 'file:///Users/hausner/tmp/e.dart': error: line 2 pos 11: semicolon expected return 5 ^ #0 main (file:///Users/hausner/tmp/e.dart:6:3) #1 _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:259) #2 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:148) $ Notice that the stack trace points to the call site of bad(), not the text location of the syntax error. That's not a bug. The location of the syntax error is given in the error message. BUG= #23684 [email protected], [email protected] Review URL: https://codereview.chromium.org/2044753002 .
dart-lang · Sep 16, 2016 · 3e0d13b · 3e0d13b
1 parent b9a5c77
commit 3e0d13b
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Showing 13 changed files with 62 additions and 5 deletions.
diff --git a/runtime/lib/errors_patch.dart b/runtime/lib/errors_patch.dart
@@ -358,3 +358,10 @@ class _InternalError {
     return msg_buf.toString();
   }
 }
+
+
+class _CompileTimeError extends Error {
+  final String _errorMsg;
+  _CompileTimeError(this._errorMsg);
+  String toString() => _errorMsg;
+}
diff --git a/runtime/vm/clustered_snapshot.cc b/runtime/vm/clustered_snapshot.cc
@@ -113,6 +113,7 @@ class ClassSerializationCluster : public SerializationCluster {
       s->WriteRef(*p);
     }
     intptr_t class_id = cls->ptr()->id_;
+    ASSERT(class_id != kIllegalCid);
     s->WriteCid(class_id);
     s->Write<int32_t>(cls->ptr()->instance_size_in_words_);
     s->Write<int32_t>(cls->ptr()->next_field_offset_in_words_);

diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
@@ -165,6 +165,10 @@ DEFINE_RUNTIME_ENTRY(CompileFunction, 1) {
   const Error& error =
       Error::Handle(Compiler::CompileFunction(thread, function));
   if (!error.IsNull()) {
+    if (error.IsLanguageError()) {
+      Exceptions::ThrowCompileTimeError(LanguageError::Cast(error));
+      UNREACHABLE();
+    }
     Exceptions::PropagateError(error);
   }
 }

diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
@@ -184,6 +184,15 @@ static RawInstance* GetMapInstance(Zone* zone, const Object& obj) {
 }
 
 
+static bool IsCompiletimeErrorObject(Zone* zone, const Object& obj) {
+  Isolate* I = Thread::Current()->isolate();
+  const Class& error_class =
+      Class::Handle(zone, I->object_store()->compiletime_error_class());
+  ASSERT(!error_class.IsNull());
+  return (obj.GetClassId() == error_class.id());
+}
+
+
 static bool GetNativeStringArgument(NativeArguments* arguments,
                                     int arg_index,
                                     Dart_Handle* str,
@@ -761,6 +770,13 @@ DART_EXPORT bool Dart_IsUnhandledExceptionError(Dart_Handle object) {
 
 
 DART_EXPORT bool Dart_IsCompilationError(Dart_Handle object) {
+  if (Dart_IsUnhandledExceptionError(object)) {
+    DARTSCOPE(Thread::Current());
+    const UnhandledException& error =
+        UnhandledException::Cast(Object::Handle(Z, Api::UnwrapHandle(object)));
+    const Instance& exc = Instance::Handle(Z, error.exception());
+    return IsCompiletimeErrorObject(Z, exc);
+  }
   return Api::ClassId(object) == kLanguageErrorCid;
 }
 

diff --git a/runtime/vm/dart_api_impl_test.cc b/runtime/vm/dart_api_impl_test.cc
@@ -570,7 +570,6 @@ TEST_CASE(Dart_PropagateError) {
 
   result = Dart_Invoke(lib, NewString("Func1"), 0, NULL);
   EXPECT(Dart_IsError(result));
-  EXPECT(!Dart_ErrorHasException(result));
   EXPECT_SUBSTRING("semicolon expected", Dart_GetError(result));
 
   result = Dart_Invoke(lib, NewString("Func2"), 0, NULL);
@@ -584,7 +583,6 @@ TEST_CASE(Dart_PropagateError) {
 
   result = Dart_Invoke(lib, NewString("Func1"), 0, NULL);
   EXPECT(Dart_IsError(result));
-  EXPECT(!Dart_ErrorHasException(result));
   EXPECT_SUBSTRING("semicolon expected", Dart_GetError(result));
 
   result = Dart_Invoke(lib, NewString("Func2"), 0, NULL);
@@ -598,7 +596,6 @@ TEST_CASE(Dart_PropagateError) {
 
   result = Dart_Invoke(lib, NewString("Func1"), 0, NULL);
   EXPECT(Dart_IsError(result));
-  EXPECT(!Dart_ErrorHasException(result));
   EXPECT_SUBSTRING("semicolon expected", Dart_GetError(result));
 
   result = Dart_Invoke(lib, NewString("Func2"), 0, NULL);

diff --git a/runtime/vm/exceptions.cc b/runtime/vm/exceptions.cc
@@ -651,6 +651,13 @@ void Exceptions::ThrowRangeError(const char* argument_name,
 }
 
 
+void Exceptions::ThrowCompileTimeError(const LanguageError& error) {
+  const Array& args = Array::Handle(Array::New(1));
+  args.SetAt(0, String::Handle(error.FormatMessage()));
+  Exceptions::ThrowByType(Exceptions::kCompileTimeError, args);
+}
+
+
 RawObject* Exceptions::Create(ExceptionType type, const Array& arguments) {
   Library& library = Library::Handle();
   const String* class_name = NULL;
@@ -724,6 +731,11 @@ RawObject* Exceptions::Create(ExceptionType type, const Array& arguments) {
     case kCyclicInitializationError:
       library = Library::CoreLibrary();
       class_name = &Symbols::CyclicInitializationError();
+      break;
+    case kCompileTimeError:
+      library = Library::CoreLibrary();
+      class_name = &Symbols::_CompileTimeError();
+      break;
   }
 
   return DartLibraryCalls::InstanceCreate(library,

diff --git a/runtime/vm/exceptions.h b/runtime/vm/exceptions.h
@@ -15,6 +15,7 @@ class AbstractType;
 class Array;
 class DartFrameIterator;
 class Error;
+class LanguageError;
 class Instance;
 class Integer;
 class RawInstance;
@@ -60,6 +61,7 @@ class Exceptions : AllStatic {
     kFallThrough,
     kAbstractClassInstantiation,
     kCyclicInitializationError,
+    kCompileTimeError,
   };
 
   static void ThrowByType(ExceptionType type, const Array& arguments);
@@ -72,6 +74,7 @@ class Exceptions : AllStatic {
                               const Integer& argument_value,
                               intptr_t expected_from,
                               intptr_t expected_to);
+  static void ThrowCompileTimeError(const LanguageError& error);
 
   // Returns a RawInstance if the exception is successfully created,
   // otherwise returns a RawError.

diff --git a/runtime/vm/object.h b/runtime/vm/object.h
@@ -5349,6 +5349,8 @@ class LanguageError : public Error {
 
   virtual const char* ToErrorCString() const;
 
+  TokenPosition token_pos() const { return raw_ptr()->token_pos_; }
+
  private:
   RawError* previous_error() const {
     return raw_ptr()->previous_error_;
@@ -5358,7 +5360,6 @@ class LanguageError : public Error {
   RawScript* script() const { return raw_ptr()->script_; }
   void set_script(const Script& value) const;
 
-  TokenPosition token_pos() const { return raw_ptr()->token_pos_; }
   void set_token_pos(TokenPosition value) const;
 
   bool report_after_token() const { return raw_ptr()->report_after_token_; }

diff --git a/runtime/vm/object_store.cc b/runtime/vm/object_store.cc
@@ -35,6 +35,7 @@ ObjectStore::ObjectStore()
     int32x4_type_(Type::null()),
     float64x2_type_(Type::null()),
     string_type_(Type::null()),
+    compiletime_error_class_(Class::null()),
     future_class_(Class::null()),
     completer_class_(Class::null()),
     stream_iterator_class_(Class::null()),
@@ -243,6 +244,11 @@ void ObjectStore::InitKnownObjects() {
   cls = internal_lib.LookupClass(Symbols::Symbol());
   set_symbol_class(cls);
 
+  const Library& core_lib = Library::Handle(core_library());
+  cls = core_lib.LookupClassAllowPrivate(Symbols::_CompileTimeError());
+  ASSERT(!cls.IsNull());
+  set_compiletime_error_class(cls);
+
   // Cache the core private functions used for fast instance of checks.
   simple_instance_of_function_ =
       PrivateObjectLookup(Symbols::_simpleInstanceOf());

diff --git a/runtime/vm/object_store.h b/runtime/vm/object_store.h
@@ -116,6 +116,13 @@ class ObjectStore {
     string_type_ = value.raw();
   }
 
+  RawClass* compiletime_error_class() const {
+    return compiletime_error_class_;
+  }
+  void set_compiletime_error_class(const Class& value) {
+    compiletime_error_class_ = value.raw();
+  }
+
   RawClass* future_class() const { return future_class_; }
   void set_future_class(const Class& value) {
     future_class_ = value.raw();
@@ -532,6 +539,7 @@ class ObjectStore {
   V(RawType*, int32x4_type_)                                                   \
   V(RawType*, float64x2_type_)                                                 \
   V(RawType*, string_type_)                                                    \
+  V(RawClass*, compiletime_error_class_)                                       \
   V(RawClass*, future_class_)                                                  \
   V(RawClass*, completer_class_)                                               \
   V(RawClass*, stream_iterator_class_)                                         \

diff --git a/runtime/vm/precompiler.cc b/runtime/vm/precompiler.cc
@@ -389,6 +389,7 @@ void Precompiler::DoCompileAll(
       I->object_store()->set_completer_class(null_class);
       I->object_store()->set_stream_iterator_class(null_class);
       I->object_store()->set_symbol_class(null_class);
+      I->object_store()->set_compiletime_error_class(null_class);
     }
     DropClasses();
     DropLibraries();

diff --git a/runtime/vm/raw_object.h b/runtime/vm/raw_object.h
@@ -1603,7 +1603,7 @@ class RawLanguageError : public RawError {
   }
   TokenPosition token_pos_;  // Source position in script_.
   bool report_after_token_;  // Report message at or after the token.
-  int8_t kind_;  // Of type LanguageError::Kind.
+  int8_t kind_;  // Of type Report::Kind.
 };
 
 

diff --git a/runtime/vm/symbols.h b/runtime/vm/symbols.h
@@ -69,6 +69,7 @@ class ObjectPointerVisitor;
   V(AbstractClassInstantiationError, "AbstractClassInstantiationError")        \
   V(NoSuchMethodError, "NoSuchMethodError")                                    \
   V(CyclicInitializationError, "CyclicInitializationError")                    \
+  V(_CompileTimeError, "_CompileTimeError")                                    \
   V(ThrowNew, "_throwNew")                                                     \
   V(ThrowNewIfNotLoaded, "_throwNewIfNotLoaded")                               \
   V(CheckAssertion, "_checkAssertion")                                         \