sdk/lib/_internal/compiler/implementation/warnings.dart

// Copyright (c) 2011, 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.

part of dart2js;

const DONT_KNOW_HOW_TO_FIX = "";

/**
 * The messages in this file should meet the following guide lines:
 *
 * 1. The message should start with exactly one of "Error", "Internal error",
 * "Warning", "Info", or "Hint" followed by a colon. It is crucial to users to
 * be able to locate errors in the midst of warnings.
 * TODO(ahe): Remove these prefixes from the error message.
 *
 * 2. After the colon, one space and a complete sentence starting with an
 * uppercase letter, and ending with a period.
 *
 * 3. Reserved words and embedded identifiers should be in single quotes, so
 * prefer double quotes for the complete message. For example, "Error: The
 * class '#{className}' can't use 'super'." Notice that the word 'class' in the
 * preceding message is not quoted as it refers to the concept 'class', not the
 * reserved word. On the other hand, 'super' refers to the reserved word. Do
 * not quote 'null' and numeric literals.
 *
 * 4. Do not try to compose messages, as it can make translating them hard.
 *
 * 5. Try to keep the error messages short, but informative.
 *
 * 6. Use simple words and terminology, assume the reader of the message
 * doesn't have an advanced degree in math, and that English is not the
 * reader's native language. Do not assume any formal computer science
 * training. For example, do not use Latin abbreviations (prefer "that is" over
 * "i.e.", and "for example" over "e.g."). Also avoid phrases such as "if and
 * only if" and "iff", that level of precision is unnecessary.
 *
 * 7. Prefer contractions when they are in common use, for example, prefer
 * "can't" over "cannot". Using "cannot", "must not", "shall not", etc. is
 * off-putting to people new to programming.
 *
 * 8. Use common terminology, preferably from the Dart Language
 * Specification. This increases the user's chance of finding a good
 * explanation on the web.
 *
 * 9. Do not try to be cute or funny. It is extremely frustrating to work on a
 * product that crashes with a "tongue-in-cheek" message, especially if you did
 * not want to use this product to begin with with.
 *
 * 10. Do not lie, that is, do not write error messages containing phrases like
 * "can't happen".  If the user ever saw this message, it would be a
 * lie. Prefer messages like: "Internal error: This function should not be
 * called when 'x' is null.".
 *
 * 11. Prefer to not use imperative tone. That is, the message should not sound
 * accusing or like it is ordering the user around. The computer should
 * describe the problem, not criticize for violating the specification.
 *
 * Other things to keep in mind:
 *
 * An INFO message should always be preceded by a non-INFO message, and the
 * INFO messages are additional details about the preceding non-INFO
 * message. For example, consider duplicated elements. First report a WARNING
 * or ERROR about the duplicated element, and then report an INFO about the
 * location of the existing element.
 *
 * Generally, we want to provide messages that consists of three sentences:
 * 1. what is wrong, 2. why is it wrong, 3. how do I fix it. However, we
 * combine the first two in [template] and the last in [howToFix].
 */
class MessageKind {
  /// Should describe what is wrong and why.
  final String template;

  /// Should describe how to fix the problem. Elided when using --terse option.
  final String howToFix;

  /// Examples will be checked by
  /// tests/compiler/dart2js/message_kind_test.dart.
  final List<String> examples;

  const MessageKind(this.template, {this.howToFix, this.examples});

  /// Do not use this. It is here for legacy and debugging. It violates item 4
  /// above.
  static const MessageKind GENERIC = const MessageKind('#{text}');

  static const DualKind NOT_ASSIGNABLE = const DualKind(
      error: const MessageKind(
          'Error: "#{fromType}" is not assignable to "#{toType}".'),
      warning: const MessageKind(
          'Warning: "#{fromType}" is not assignable to "#{toType}".'));

  static const MessageKind VOID_EXPRESSION = const MessageKind(
      'Warning: Expression does not yield a value.');

  static const MessageKind VOID_VARIABLE = const MessageKind(
      'Warning: Variable cannot be of type void.');

  static const MessageKind RETURN_VALUE_IN_VOID = const MessageKind(
      'Warning: Cannot return value from void function.');

  static const MessageKind RETURN_NOTHING = const MessageKind(
      'Warning: Value of type "#{returnType}" expected.');

  static const MessageKind MISSING_ARGUMENT = const MessageKind(
      'Warning: Missing argument of type "#{argumentType}".');

  static const MessageKind ADDITIONAL_ARGUMENT = const MessageKind(
      'Warning: Additional argument.');

  static const MessageKind NAMED_ARGUMENT_NOT_FOUND = const MessageKind(
      'Warning: No named argument "#{argumentName}" found on method.');

  static const DualKind MEMBER_NOT_FOUND = const DualKind(
      error: const MessageKind(
          'Error: No member named "#{memberName}" in class "#{className}".'),
      warning: const MessageKind(
          'Warning: No member named "#{memberName}" in class "#{className}".'));

  static const MessageKind METHOD_NOT_FOUND = const MessageKind(
      'Warning: No method named "#{memberName}" in class "#{className}".');

  static const MessageKind OPERATOR_NOT_FOUND = const MessageKind(
      'Warning: No operator "#{memberName}" in class "#{className}".');

  static const MessageKind PROPERTY_NOT_FOUND = const MessageKind(
      'Warning: No property named "#{memberName}" in class "#{className}".');

  static const MessageKind NOT_CALLABLE = const MessageKind(
      'Warning: "#{elementName}" is not callable.');

  static const DualKind MEMBER_NOT_STATIC = const DualKind(
      error: const MessageKind(
          'Error: "#{className}.#{memberName}" is not static.'),
      warning: const MessageKind(
          'Warning: "#{className}.#{memberName}" is not static.'));

  static const MessageKind NO_INSTANCE_AVAILABLE = const MessageKind(
      'Error: "#{name}" is only available in instance methods.');

  static const MessageKind PRIVATE_ACCESS = const MessageKind(
      'Warning: "#{name}" is declared private within library '
      '"#{libraryName}".');

  static const MessageKind THIS_IS_THE_METHOD = const MessageKind(
      'Info: This is the method declaration.');

  static const MessageKind UNREACHABLE_CODE = const MessageKind(
      'Warning: Unreachable code.');

  static const MessageKind MISSING_RETURN = const MessageKind(
      'Warning: Missing return.');

  static const MessageKind MAYBE_MISSING_RETURN = const MessageKind(
      'Warning: Not all paths lead to a return or throw statement.');

  static const DualKind CANNOT_RESOLVE = const DualKind(
      error: const MessageKind('Error: Cannot resolve "#{name}".'),
      warning: const MessageKind('Warning: Cannot resolve "#{name}".'));

  static const MessageKind CANNOT_RESOLVE_CONSTRUCTOR = const MessageKind(
      'Error: Cannot resolve constructor "#{constructorName}".');

  static const MessageKind CANNOT_RESOLVE_CONSTRUCTOR_FOR_IMPLICIT =
      const MessageKind(
          'Error: cannot resolve constructor "#{constructorName}" for implicit'
          'super call.');

  static const MessageKind INVALID_UNNAMED_CONSTRUCTOR_NAME = const MessageKind(
      'Error: Unnamed constructor name must be "#{name}".');

  static const MessageKind INVALID_CONSTRUCTOR_NAME = const MessageKind(
      'Error: Constructor name must start with "#{name}".');

  static const DualKind CANNOT_RESOLVE_TYPE = const DualKind(
      error: const MessageKind('Error: Cannot resolve type "#{typeName}".'),
      warning: const MessageKind(
          'Warning: Cannot resolve type "#{typeName}".'));

  static const MessageKind DUPLICATE_DEFINITION = const MessageKind(
      'Error: Duplicate definition of "#{name}".');

  static const MessageKind EXISTING_DEFINITION = const MessageKind(
      'Info: Existing definition of "#{name}".');

  static const DualKind DUPLICATE_IMPORT = const DualKind(
      error: const MessageKind('Error: Duplicate import of "#{name}".'),
      warning: const MessageKind('Warning: Duplicate import of "#{name}".'));

  static const MessageKind DUPLICATE_EXPORT = const MessageKind(
      'Error: Duplicate export of "#{name}".');

  static const DualKind NOT_A_TYPE = const DualKind(
      error: const MessageKind('Error: "#{node}" is not a type.'),
      warning: const MessageKind('Warning: "#{node}" is not a type.'));

  static const MessageKind NOT_A_PREFIX = const MessageKind(
      'Error: "#{node}" is not a prefix.');

  static const DualKind CANNOT_FIND_CONSTRUCTOR = const DualKind(
      error: const MessageKind(
          'Error: Cannot find constructor "#{constructorName}".'),
      warning: const MessageKind(
          'Warning: Cannot find constructor "#{constructorName}".'));

  static const MessageKind CYCLIC_CLASS_HIERARCHY = const MessageKind(
      'Error: "#{className}" creates a cycle in the class hierarchy.');

  static const MessageKind INVALID_RECEIVER_IN_INITIALIZER = const MessageKind(
      'Error: Field initializer expected.');

  static const MessageKind NO_SUPER_IN_STATIC = const MessageKind(
      'Error: "super" is only available in instance methods.');

  static const MessageKind DUPLICATE_INITIALIZER = const MessageKind(
      'Error: Field "#{fieldName}" is initialized more than once.');

  static const MessageKind ALREADY_INITIALIZED = const MessageKind(
      'Info: "#{fieldName}" was already initialized here.');

  static const MessageKind INIT_STATIC_FIELD = const MessageKind(
      'Error: Cannot initialize static field "#{fieldName}".');

  static const MessageKind NOT_A_FIELD = const MessageKind(
      'Error: "#{fieldName}" is not a field.');

  static const MessageKind CONSTRUCTOR_CALL_EXPECTED = const MessageKind(
      'Error: only call to "this" or "super" constructor allowed.');

  static const MessageKind INVALID_FOR_IN = const MessageKind(
      'Error: Invalid for-in variable declaration.');

  static const MessageKind INVALID_INITIALIZER = const MessageKind(
      'Error: Invalid initializer.');

  static const MessageKind FUNCTION_WITH_INITIALIZER = const MessageKind(
      'Error: Only constructors can have initializers.');

  static const MessageKind REDIRECTING_CONSTRUCTOR_CYCLE = const MessageKind(
      'Error: Cyclic constructor redirection.');

  static const MessageKind REDIRECTING_CONSTRUCTOR_HAS_BODY = const MessageKind(
      'Error: Redirecting constructor cannot have a body.');

  static const MessageKind REDIRECTING_CONSTRUCTOR_HAS_INITIALIZER =
      const MessageKind(
          'Error: Redirecting constructor cannot have other initializers.');

  static const MessageKind SUPER_INITIALIZER_IN_OBJECT = const MessageKind(
      'Error: "Object" cannot have a super initializer.');

  static const MessageKind DUPLICATE_SUPER_INITIALIZER = const MessageKind(
      'Error: Cannot have more than one super initializer.');

  static const DualKind INVALID_ARGUMENTS = const DualKind(
      error: const MessageKind(
          'Error: Arguments do not match the expected parameters of '
          '"#{methodName}".'),
      warning: const MessageKind(
          'Warning: Arguments do not match the expected parameters of '
          '"#{methodName}".'));

  static const MessageKind NO_MATCHING_CONSTRUCTOR = const MessageKind(
      'Error: "super" call arguments and constructor parameters do not match.');

  static const MessageKind NO_MATCHING_CONSTRUCTOR_FOR_IMPLICIT =
      const MessageKind(
          'Error: Implicit "super" call arguments and constructor parameters '
          'do not match.');

  static const MessageKind CONST_CALLS_NON_CONST = const MessageKind(
      'Error: "const" constructor cannot call a non-const constructor.');

  static const MessageKind INITIALIZING_FORMAL_NOT_ALLOWED = const MessageKind(
      'Error: Initializing formal parameter only allowed in generative '
      'constructor.');

  static const MessageKind INVALID_PARAMETER = const MessageKind(
      'Error: Cannot resolve parameter.');

  static const MessageKind NOT_INSTANCE_FIELD = const MessageKind(
      'Error: "#{fieldName}" is not an instance field.');

  static const MessageKind NO_CATCH_NOR_FINALLY = const MessageKind(
      'Error: Expected "catch" or "finally".');

  static const MessageKind EMPTY_CATCH_DECLARATION = const MessageKind(
      'Error: Expected an identifier in catch declaration.');

  static const MessageKind EXTRA_CATCH_DECLARATION = const MessageKind(
      'Error: Extra parameter in catch declaration.');

  static const MessageKind PARAMETER_WITH_TYPE_IN_CATCH = const MessageKind(
      'Error: Cannot use type annotations in catch.');

  static const MessageKind PARAMETER_WITH_MODIFIER_IN_CATCH = const MessageKind(
      'Error: Cannot use modifiers in catch.');

  static const MessageKind OPTIONAL_PARAMETER_IN_CATCH = const MessageKind(
      'Error: Cannot use optional parameters in catch.');

  static const MessageKind THROW_WITHOUT_EXPRESSION = const MessageKind(
      'Error: Cannot use re-throw outside of catch block '
      '(expression expected after "throw").');

  static const MessageKind UNBOUND_LABEL = const MessageKind(
      'Error: Cannot resolve label "#{labelName}".');

  static const MessageKind NO_BREAK_TARGET = const MessageKind(
      'Error: "break" statement not inside switch or loop.');

  static const MessageKind NO_CONTINUE_TARGET = const MessageKind(
      'Error: "continue" statement not inside loop.');

  static const MessageKind EXISTING_LABEL = const MessageKind(
      'Info: Original declaration of duplicate label "#{labelName}".');

  static const DualKind DUPLICATE_LABEL = const DualKind(
      error: const MessageKind(
          'Error: Duplicate declaration of label "#{labelName}".'),
      warning: const MessageKind(
          'Warning: Duplicate declaration of label "#{labelName}".'));

  static const MessageKind UNUSED_LABEL = const MessageKind(
      'Warning: Unused label "#{labelName}".');

  static const MessageKind INVALID_CONTINUE = const MessageKind(
      'Error: Target of continue is not a loop or switch case.');

  static const MessageKind INVALID_BREAK = const MessageKind(
      'Error: Target of break is not a statement.');

  static const MessageKind DUPLICATE_TYPE_VARIABLE_NAME = const MessageKind(
      'Error: Type variable "#{typeVariableName}" already declared.');

  static const DualKind TYPE_VARIABLE_WITHIN_STATIC_MEMBER = const DualKind(
      error: const MessageKind(
          'Error: Cannot refer to type variable "#{typeVariableName}" '
          'within a static member.'),
      warning: const MessageKind(
          'Warning: Cannot refer to type variable "#{typeVariableName}" '
          'within a static member.'));

  static const MessageKind TYPE_VARIABLE_IN_CONSTANT = const MessageKind(
      'Error: Cannot refer to type variable in constant.');

  static const MessageKind INVALID_USE_OF_SUPER = const MessageKind(
      'Error: "super" not allowed here.');

  static const MessageKind INVALID_CASE_DEFAULT = const MessageKind(
      'Error: "default" only allowed on last case of a switch.');

  static const MessageKind SWITCH_CASE_TYPES_NOT_EQUAL = const MessageKind(
      'Error: "case" expressions do not all have type "#{type}".');

  static const MessageKind SWITCH_CASE_TYPES_NOT_EQUAL_CASE = const MessageKind(
      'Info: "case" expression of type "#{type}".');

  static const MessageKind SWITCH_CASE_VALUE_OVERRIDES_EQUALS =
      const MessageKind(
          'Error: "case" expression value overrides "operator==".');

  static const MessageKind INVALID_ARGUMENT_AFTER_NAMED = const MessageKind(
      'Error: Unnamed argument after named argument.');

  static const MessageKind NOT_A_COMPILE_TIME_CONSTANT = const MessageKind(
      'Error: Not a compile-time constant.');

  static const MessageKind CYCLIC_COMPILE_TIME_CONSTANTS = const MessageKind(
      'Error: Cycle in the compile-time constant computation.');

  static const MessageKind CONSTRUCTOR_IS_NOT_CONST = const MessageKind(
      'Error: Constructor is not a "const" constructor.');

  static const MessageKind KEY_NOT_A_STRING_LITERAL = const MessageKind(
      'Error: Map-literal key not a string literal.');

  static const DualKind NO_SUCH_LIBRARY_MEMBER = const DualKind(
      error: const MessageKind(
          'Error: "#{libraryName}" has no member named "#{memberName}".'),
      warning: const MessageKind(
          'Warning: "#{libraryName}" has no member named "#{memberName}".'));

  static const MessageKind CANNOT_INSTANTIATE_TYPEDEF = const MessageKind(
      'Error: Cannot instantiate typedef "#{typedefName}".');

  static const MessageKind CANNOT_INSTANTIATE_TYPE_VARIABLE = const MessageKind(
      'Error: Cannot instantiate type variable "#{typeVariableName}".');

  static const MessageKind CYCLIC_TYPE_VARIABLE = const MessageKind(
      'Warning: Type variable "#{typeVariableName}" is a supertype of itself.');

  static const MessageKind CLASS_NAME_EXPECTED = const MessageKind(
      'Error: Class name expected.');

  static const MessageKind CANNOT_EXTEND = const MessageKind(
      'Error: "#{type}" cannot be extended.');

  static const MessageKind CANNOT_IMPLEMENT = const MessageKind(
      'Error: "#{type}" cannot be implemented.');

  static const MessageKind DUPLICATE_EXTENDS_IMPLEMENTS = const MessageKind(
      'Error: "#{type}" can not be both extended and implemented.');

  static const MessageKind DUPLICATE_IMPLEMENTS = const MessageKind(
      'Error: "#{type}" must not occur more than once '
      'in the implements clause.');

  static const MessageKind ILLEGAL_SUPER_SEND = const MessageKind(
      'Error: "#{name}" cannot be called on super.');

  static const DualKind NO_SUCH_SUPER_MEMBER = const DualKind(
      error: const MessageKind(
          'Error: Cannot resolve "#{memberName}" in a superclass of '
          '"#{className}".'),
      warning: const MessageKind(
          'Warning: Cannot resolve "#{memberName}" in a superclass of '
          '"#{className}".'));

  static const DualKind ADDITIONAL_TYPE_ARGUMENT = const DualKind(
      error: const MessageKind('Error: Additional type argument.'),
      warning: const MessageKind('Warning: Additional type argument.'));

  static const DualKind MISSING_TYPE_ARGUMENT = const DualKind(
      error: const MessageKind('Error: Missing type argument.'),
      warning: const MessageKind('Warning: Missing type argument.'));

  // TODO(johnniwinther): Use ADDITIONAL_TYPE_ARGUMENT or MISSING_TYPE_ARGUMENT
  // instead.
  static const MessageKind TYPE_ARGUMENT_COUNT_MISMATCH = const MessageKind(
      'Error: Incorrect number of type arguments on "#{type}".');

  static const MessageKind GETTER_MISMATCH = const MessageKind(
      'Error: Setter disagrees on: "#{modifiers}".');

  static const MessageKind SETTER_MISMATCH = const MessageKind(
      'Error: Getter disagrees on: "#{modifiers}".');

  static const MessageKind ILLEGAL_SETTER_FORMALS = const MessageKind(
      'Error: A setter must have exactly one argument.');

  static const MessageKind NO_STATIC_OVERRIDE = const MessageKind(
      'Error: Static member cannot override instance member "#{memberName}" of '
      '"#{className}".');

  static const MessageKind NO_STATIC_OVERRIDE_CONT = const MessageKind(
      'Info: This is the instance member that cannot be overridden '
      'by a static member.');

  static const MessageKind CANNOT_OVERRIDE_FIELD_WITH_METHOD =
      const MessageKind(
          'Error: Method cannot override field "#{memberName}" of '
          '"#{className}".');

  static const MessageKind CANNOT_OVERRIDE_FIELD_WITH_METHOD_CONT =
      const MessageKind(
          'Info: This is the field that cannot be overridden by a method.');

  static const MessageKind CANNOT_OVERRIDE_METHOD_WITH_FIELD =
      const MessageKind(
          'Error: Field cannot override method "#{memberName}" of '
          '"#{className}".');

  static const MessageKind CANNOT_OVERRIDE_METHOD_WITH_FIELD_CONT =
      const MessageKind(
          'Info: This is the method that cannot be overridden by a field.');

  static const MessageKind BAD_ARITY_OVERRIDE = const MessageKind(
      'Error: Cannot override method "#{memberName}" in "#{className}"; '
      'the parameters do not match.');

  static const MessageKind BAD_ARITY_OVERRIDE_CONT = const MessageKind(
      'Info: This is the method whose parameters do not match.');

  static const MessageKind MISSING_FORMALS = const MessageKind(
      'Error: Formal parameters are missing.');

  static const MessageKind EXTRA_FORMALS = const MessageKind(
      'Error: Formal parameters are not allowed here.');

  static const MessageKind UNARY_OPERATOR_BAD_ARITY = const MessageKind(
      'Error: Operator "#{operatorName}" must have no parameters.');

  static const MessageKind MINUS_OPERATOR_BAD_ARITY = const MessageKind(
      'Error: Operator "-" must have 0 or 1 parameters.');

  static const MessageKind BINARY_OPERATOR_BAD_ARITY = const MessageKind(
      'Error: Operator "#{operatorName}" must have exactly 1 parameter.');

  static const MessageKind TERNARY_OPERATOR_BAD_ARITY = const MessageKind(
      'Error: Operator "#{operatorName}" must have exactly 2 parameters.');

  static const MessageKind OPERATOR_OPTIONAL_PARAMETERS = const MessageKind(
      'Error: Operator "#{operatorName}" cannot have optional parameters.');

  static const MessageKind OPERATOR_NAMED_PARAMETERS = const MessageKind(
      'Error: Operator "#{operatorName}" cannot have named parameters.');

  static const MessageKind CONSTRUCTOR_WITH_RETURN_TYPE = const MessageKind(
      'Error: Cannot have return type for constructor.');

  static const MessageKind ILLEGAL_FINAL_METHOD_MODIFIER = const MessageKind(
      'Error: Cannot have final modifier on method.');

  static const MessageKind ILLEGAL_CONSTRUCTOR_MODIFIERS = const MessageKind(
      'Error: Illegal constructor modifiers: "#{modifiers}".');

  static const MessageKind ILLEGAL_MIXIN_APPLICATION_MODIFIERS =
      const MessageKind(
          'Error: Illegal mixin application modifiers: "#{modifiers}".');

  static const MessageKind ILLEGAL_MIXIN_SUPERCLASS = const MessageKind(
      'Error: Class used as mixin must have Object as superclass.');

  static const MessageKind ILLEGAL_MIXIN_OBJECT = const MessageKind(
      'Error: Cannot use Object as mixin.');

  static const MessageKind ILLEGAL_MIXIN_CONSTRUCTOR = const MessageKind(
      'Error: Class used as mixin cannot have non-factory constructor.');

  static const MessageKind ILLEGAL_MIXIN_CYCLE = const MessageKind(
      'Error: Class used as mixin introduces mixin cycle: '
      '"#{mixinName1}" <-> "#{mixinName2}".');

  static const MessageKind ILLEGAL_MIXIN_WITH_SUPER = const MessageKind(
      'Error: Cannot use class "#{className}" as a mixin because it uses '
      '"super".');

  static const MessageKind ILLEGAL_MIXIN_SUPER_USE = const MessageKind(
      'Info: Use of "super" in class used as mixin.');

  static const MessageKind PARAMETER_NAME_EXPECTED = const MessageKind(
      'Error: parameter name expected.');

  static const DualKind CANNOT_RESOLVE_GETTER = const DualKind(
      error: const MessageKind('Error: Cannot resolve getter.'),
      warning: const MessageKind('Warning: Cannot resolve getter.'));

  static const DualKind CANNOT_RESOLVE_SETTER = const DualKind(
      error: const MessageKind('Error: Cannot resolve setter.'),
      warning: const MessageKind('Warning: Cannot resolve setter.'));

  static const MessageKind VOID_NOT_ALLOWED = const MessageKind(
      "Error: Type 'void' can't be used here because it isn't a return type.",
      howToFix: "Try removing 'void' keyword or replace it with 'var', 'final',"
          " or a type.",
      examples: const [
          "void x; main() {}",
          "foo(void x) {} main() { foo(null); }",
      ]);

  static const MessageKind BEFORE_TOP_LEVEL = const MessageKind(
      'Error: Part header must come before top-level definitions.');

  static const MessageKind LIBRARY_NAME_MISMATCH = const MessageKind(
      'Warning: Expected part of library name "#{libraryName}".');

  static const MessageKind MISSING_PART_OF_TAG = const MessageKind(
      'Error: This file has no part-of tag, but it is being used as a part.');

  static const MessageKind DUPLICATED_PART_OF = const MessageKind(
      'Error: Duplicated part-of directive.');

  static const MessageKind ILLEGAL_DIRECTIVE = const MessageKind(
      'Error: Directive not allowed here.');

  static const MessageKind DUPLICATED_LIBRARY_NAME = const MessageKind(
      'Warning: Duplicated library name "#{libraryName}".');

  // This is used as an exception.
  static const MessageKind INVALID_SOURCE_FILE_LOCATION = const MessageKind('''
Invalid offset (#{offset}) in source map.
File: #{fileName}
Length: #{length}''');

  static const MessageKind TOP_LEVEL_VARIABLE_DECLARED_STATIC =
      const MessageKind(
          'Error: Top-level variable cannot be declared static.');

  static const MessageKind WRONG_NUMBER_OF_ARGUMENTS_FOR_ASSERT =
      const MessageKind(
          'Error: Wrong number of arguments to assert. Should be 1, but given '
          '#{argumentCount}.');

  static const MessageKind ASSERT_IS_GIVEN_NAMED_ARGUMENTS = const MessageKind(
      'Error: "assert" takes no named arguments, but given #{argumentCount}.');

  static const MessageKind FACTORY_REDIRECTION_IN_NON_FACTORY =
      const MessageKind(
          'Error: Factory redirection only allowed in factories.');

  static const MessageKind MISSING_FACTORY_KEYWORD = const MessageKind(
      'Hint: Did you forget a factory keyword here?');

  static const MessageKind DEFERRED_LIBRARY_NAME_MISMATCH =
      const MessageKind(
          'Error: Library name mismatch "#{expectedName}" != "#{actualName}".');

  static const MessageKind ILLEGAL_STATIC = const MessageKind(
      'Error: Modifier static is only allowed on functions declared in '
      'a class.');

  static const MessageKind STATIC_FUNCTION_BLOAT = const MessageKind(
      'Hint: Using "#{class}.#{name}" may result in larger output.');

  static const MessageKind NON_CONST_BLOAT = const MessageKind('''
Hint: Using "new #{name}" may result in larger output.
Use "const #{name}" if possible.''');

  static const MessageKind STRING_EXPECTED = const MessageKind(
      'Error: Expected a "String", but got an instance of "#{type}".');

  static const MessageKind PRIVATE_IDENTIFIER = const MessageKind(
      'Error: "#{value}" is not a valid Symbol name because it starts with '
      '"_".');

  static const MessageKind INVALID_SYMBOL = const MessageKind('''
Error: "#{value}" is not a valid Symbol name because is not:
 * an empty String,
 * a user defined operator,
 * a qualified non-private identifier optionally followed by "=", or
 * a qualified non-private identifier followed by "." and a user-defined '''
'operator.');

  static const MessageKind AMBIGUOUS_REEXPORT = const MessageKind(
      'Info: "#{element}" is (re)exported by multiple libraries.');

  static const MessageKind AMBIGUOUS_LOCATION = const MessageKind(
      'Info: "#{element}" is defined here.');

  static const MessageKind IMPORTED_HERE = const MessageKind(
      'Info: "#{element}" is imported here.');

  static const MessageKind OVERRIDE_EQUALS_NOT_HASH_CODE = const MessageKind(
      'Hint: The class "#{class}" overrides "operator==", '
      'but not "get hashCode".');

  static const MessageKind PACKAGE_ROOT_NOT_SET = const MessageKind(
      'Error: Cannot resolve "#{uri}". Package root has not been set.');

  static const MessageKind INTERNAL_LIBRARY_FROM = const MessageKind(
      'Error: Internal library "#{resolvedUri}" is not accessible from '
      '"#{importingUri}".');

  static const MessageKind INTERNAL_LIBRARY = const MessageKind(
      'Error: Internal library "#{resolvedUri}" is not accessible.');

  static const MessageKind LIBRARY_NOT_FOUND = const MessageKind(
      'Error: Library not found "#{resolvedUri}".');

  static const MessageKind UNSUPPORTED_EQ_EQ_EQ = const MessageKind(
      'Error: "===" is not an operator. '
      'Did you mean "#{lhs} == #{rhs}" or "identical(#{lhs}, #{rhs})"?');

  static const MessageKind UNSUPPORTED_BANG_EQ_EQ = const MessageKind(
      'Error: "!==" is not an operator. '
      'Did you mean "#{lhs} != #{rhs}" or "!identical(#{lhs}, #{rhs})"?');

  static const MessageKind UNSUPPORTED_THROW_WITHOUT_EXP = const MessageKind(
      'Error: No expression after "throw". '
      'Did you mean "rethrow"?');

  static const MessageKind MIRRORS_EXPECTED_STRING = const MessageKind(
      "Hint: Can't use '#{name}' here because it's an instance of '#{type}' "
      "and a 'String' value is expected.",
      howToFix: "Did you forget to add quotes?",
      examples: const [
          """
// 'Foo' is a type literal, not a string.
@MirrorsUsed(symbols: const [Foo])
import 'dart:mirrors';

class Foo {}

main() {}
"""]);

  static const MessageKind MIRRORS_EXPECTED_STRING_OR_TYPE = const MessageKind(
      "Hint: Can't use '#{name}' here because it's an instance of '#{type}' "
      "and a 'String' or 'Type' value is expected.",
      howToFix: "Did you forget to add quotes?",
      examples: const [
          """
// 'main' is a method, not a class.
@MirrorsUsed(targets: const [main])
import 'dart:mirrors';

main() {}
"""]);

  static const MessageKind MIRRORS_EXPECTED_STRING_OR_LIST = const MessageKind(
      "Hint: Can't use '#{name}' here because it's an instance of '#{type}' "
      "and a 'String' or 'List' value is expected.",
      howToFix: "Did you forget to add quotes?",
      examples: const [
          """
// 'Foo' is not a string.
@MirrorsUsed(symbols: Foo)
import 'dart:mirrors';

class Foo {}

main() {}
"""]);

  static const MessageKind MIRRORS_EXPECTED_STRING_TYPE_OR_LIST =
      const MessageKind(
      "Hint: Can't use '#{name}' here because it's an instance of '#{type}' "
      "but a 'String', 'Type', or 'List' value is expected.",
      howToFix: "Did you forget to add quotes?",
      examples: const [
          """
// '1' is not a string.
@MirrorsUsed(targets: 1)
import 'dart:mirrors';

main() {}
"""]);

  static const MessageKind MIRRORS_CANNOT_RESOLVE_IN_CURRENT_LIBRARY =
      const MessageKind(
      "Hint: Can't find '#{name}' in the current library.",
      // TODO(ahe): The closest identifiers in edit distance would be nice.
      howToFix: "Did you forget to add an import?",
      examples: const [
          """
// 'window' is not in scope because dart:html isn't imported.
@MirrorsUsed(targets: 'window')
import 'dart:mirrors';

main() {}
"""]);

  static const MessageKind MIRRORS_CANNOT_RESOLVE_IN_LIBRARY =
      const MessageKind(
      "Hint: Can't find '#{name}' in the library '#{library}'.",
      // TODO(ahe): The closest identifiers in edit distance would be nice.
      howToFix: "Is '#{name}' spelled right?",
      examples: const [
          """
// 'List' is misspelled.
@MirrorsUsed(targets: 'dart.core.Lsit')
import 'dart:mirrors';

main() {}
"""]);

  static const MessageKind MIRRORS_CANNOT_FIND_IN_ELEMENT =
      const MessageKind(
      "Hint: Can't find '#{name}' in '#{element}'.",
      // TODO(ahe): The closest identifiers in edit distance would be nice.
      howToFix: "Is '#{name}' spelled right?",
      examples: const [
          """
// 'addAll' is misspelled.
@MirrorsUsed(targets: 'dart.core.List.addAl')
import 'dart:mirrors';

main() {}
"""]);

  static const MessageKind READ_SCRIPT_ERROR = const MessageKind(
      "Error: Can't read '#{uri}' (#{exception}).",
      // Don't know how to fix since the underlying error is unknown.
      howToFix: DONT_KNOW_HOW_TO_FIX,
      examples: const [
          """
// 'foo.dart' does not exist.
import 'foo.dart';

main() {}
"""]);

  static const MessageKind EXTRANEOUS_MODIFIER = const MessageKind(
      "Error: Can't have modifier '#{modifier}' here.",
      howToFix: "Try removing '#{modifier}'.",
      examples: const [
          "var String foo; main(){}",
          // "var get foo; main(){}",
          "var set foo; main(){}",
          "var final foo; main(){}",
          "var var foo; main(){}",
          "var const foo; main(){}",
          "var abstract foo; main(){}",
          "var static foo; main(){}",
          "var external foo; main(){}",
          "get var foo; main(){}",
          "set var foo; main(){}",
          "final var foo; main(){}",
          "var var foo; main(){}",
          "const var foo; main(){}",
          "abstract var foo; main(){}",
          "static var foo; main(){}",
          "external var foo; main(){}"]);

  static const MessageKind EXTRANEOUS_MODIFIER_REPLACE = const MessageKind(
      "Error: Can't have modifier '#{modifier}' here.",
      howToFix: "Try replacing modifier '#{modifier}' with 'var', 'final',"
          " or a type.",
      examples: const [
          // "get foo; main(){}",
          "set foo; main(){}",
          "abstract foo; main(){}",
          "static foo; main(){}",
          "external foo; main(){}"]);

  static const MessageKind BODY_EXPECTED = const MessageKind(
      "Error: Expected a function body or '=>'.",
      // TODO(ahe): In some scenarios, we can suggest removing the 'static'
      // keyword.
      howToFix: "Try adding {}.",
      examples: const [
          "main();"]);

  static const MessageKind COMPILER_CRASHED = const MessageKind(
      'Error: The compiler crashed when compiling this element.');

  static const MessageKind PLEASE_REPORT_THE_CRASH = const MessageKind('''
The compiler is broken.

When compiling the above element, the compiler crashed. It is not
possible to tell if this is caused by a problem in your program or
not. Regardless, the compiler should not crash.

The Dart team would greatly appreciate if you would take a moment to
report this problem at http://dartbug.com/new.

Please include the following information:

* the name and version of your operating system,

* the Dart SDK build number (#{buildId}), and

* the entire message you see here (including the full stack trace
  below as well as the source location above).
''');


  //////////////////////////////////////////////////////////////////////////////
  // Patch errors start.
  //////////////////////////////////////////////////////////////////////////////

  static const MessageKind PATCH_RETURN_TYPE_MISMATCH = const MessageKind(
      'Error: Patch return type "#{patchReturnType}" does not match '
      '"#{originReturnType}" on origin method "#{methodName}".');

  static const MessageKind PATCH_REQUIRED_PARAMETER_COUNT_MISMATCH =
      const MessageKind(
          'Error: Required parameter count of patch method '
          '(#{patchParameterCount}) does not match parameter count on origin '
          'method "#{methodName}" (#{originParameterCount}).');

  static const MessageKind PATCH_OPTIONAL_PARAMETER_COUNT_MISMATCH =
      const MessageKind(
          'Error: Optional parameter count of patch method '
          '(#{patchParameterCount}) does not match parameter count on origin '
          'method "#{methodName}" (#{originParameterCount}).');

  static const MessageKind PATCH_OPTIONAL_PARAMETER_NAMED_MISMATCH =
      const MessageKind(
          'Error: Optional parameters of origin and patch method '
          '"#{methodName}" must both be either named or positional.');

  static const MessageKind PATCH_PARAMETER_MISMATCH = const MessageKind(
      'Error: Patch method parameter "#{patchParameter}" does not match '
      '"#{originParameter}" on origin method "#{methodName}".');

  static const MessageKind PATCH_PARAMETER_TYPE_MISMATCH = const MessageKind(
      'Error: Patch method parameter "#{parameterName}" type '
      '"#{patchParameterType}" does not match "#{originParameterType}" on '
      'origin method "#{methodName}".');

  static const MessageKind PATCH_EXTERNAL_WITHOUT_IMPLEMENTATION =
      const MessageKind('Error: External method without an implementation.');

  static const MessageKind PATCH_POINT_TO_FUNCTION = const MessageKind(
      'Info: This is the function patch "#{functionName}".');

  static const MessageKind PATCH_POINT_TO_CLASS = const MessageKind(
      'Info: This is the class patch "#{className}".');

  static const MessageKind PATCH_POINT_TO_GETTER = const MessageKind(
      'Info: This is the getter patch "#{getterName}".');

  static const MessageKind PATCH_POINT_TO_SETTER = const MessageKind(
      'Info: This is the setter patch "#{setterName}".');

  static const MessageKind PATCH_POINT_TO_CONSTRUCTOR = const MessageKind(
      'Info: This is the constructor patch "#{constructorName}".');

  static const MessageKind PATCH_POINT_TO_PARAMETER = const MessageKind(
      'Info: This is the patch parameter "#{parameterName}".');

  static const MessageKind PATCH_NON_EXISTING = const MessageKind(
      'Error: Origin does not exist for patch "#{name}".');

  // TODO(ahe): Eventually, this error should be removed as it will be handled
  // by the regular parser.
  static const MessageKind PATCH_NONPATCHABLE = const MessageKind(
      'Error: Only classes and functions can be patched.');

  static const MessageKind PATCH_NON_EXTERNAL = const MessageKind(
      'Error: Only external functions can be patched.');

  static const MessageKind PATCH_NON_CLASS = const MessageKind(
      'Error: Patching non-class with class patch "#{className}".');

  static const MessageKind PATCH_NON_GETTER = const MessageKind(
      'Error: Cannot patch non-getter "#{name}" with getter patch.');

  static const MessageKind PATCH_NO_GETTER = const MessageKind(
      'Error: No getter found for getter patch "#{getterName}".');

  static const MessageKind PATCH_NON_SETTER = const MessageKind(
      'Error: Cannot patch non-setter "#{name}" with setter patch.');

  static const MessageKind PATCH_NO_SETTER = const MessageKind(
      'Error: No setter found for setter patch "#{setterName}".');

  static const MessageKind PATCH_NON_CONSTRUCTOR = const MessageKind(
      'Error: Cannot patch non-constructor with constructor patch '
      '"#{constructorName}".');

  static const MessageKind PATCH_NON_FUNCTION = const MessageKind(
      'Error: Cannot patch non-function with function patch '
      '"#{functionName}".');

  //////////////////////////////////////////////////////////////////////////////
  // Patch errors end.
  //////////////////////////////////////////////////////////////////////////////

  toString() => template;

  Message message([Map arguments = const {}, bool terse = false]) {
    return new Message(this, arguments, terse);
  }

  CompilationError error([Map arguments = const {}, bool terse = false]) {
    return new CompilationError(this, arguments, terse);
  }

  bool get hasHowToFix => howToFix != null && howToFix != DONT_KNOW_HOW_TO_FIX;
}

class DualKind {
  final MessageKind error;
  final MessageKind warning;

  const DualKind({this.error, this.warning});
}

class Message {
  final MessageKind kind;
  final Map arguments;
  final bool terse;
  String message;

  Message(this.kind, this.arguments, this.terse) {
    assert(() { computeMessage(); return true; });
  }

  String computeMessage() {
    if (message == null) {
      message = kind.template;
      arguments.forEach((key, value) {
        String string = slowToString(value);
        message = message.replaceAll('#{${key}}', string);
      });
      assert(invariant(
          CURRENT_ELEMENT_SPANNABLE,
          !message.contains(new RegExp(r'#\{.+\}')),
          message: 'Missing arguments in error message: "$message"'));
      if (!terse && kind.hasHowToFix) {
        String howToFix = kind.howToFix;
        arguments.forEach((key, value) {
          String string = slowToString(value);
          howToFix = howToFix.replaceAll('#{${key}}', string);
        });
        message = '$message\n$howToFix';
      }
    }
    return message;
  }

  String toString() {
    return computeMessage();
  }

  bool operator==(other) {
    if (other is !Message) return false;
    return (kind == other.kind) && (toString() == other.toString());
  }

  int get hashCode => throw new UnsupportedError('Message.hashCode');

  String slowToString(object) {
    if (object is SourceString) {
      return object.slowToString();
    } else {
      return object.toString();
    }
  }
}

class Diagnostic {
  final Message message;
  Diagnostic(MessageKind kind, Map arguments, bool terse)
      : message = new Message(kind, arguments, terse);
  String toString() => message.toString();
}

class TypeWarning extends Diagnostic {
  TypeWarning(MessageKind kind, Map arguments, bool terse)
    : super(kind, arguments, terse);
}

class ResolutionWarning extends Diagnostic {
  ResolutionWarning(MessageKind kind, Map arguments, bool terse)
    : super(kind, arguments, terse);
}

class CompileTimeConstantError extends Diagnostic {
  CompileTimeConstantError(MessageKind kind, Map arguments, bool terse)
    : super(kind, arguments, terse);
}

class CompilationError extends Diagnostic {
  CompilationError(MessageKind kind, Map arguments, bool terse)
    : super(kind, arguments, terse);
}