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Fixes #151
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Type check async-return, async*-yield, and sync*-yield.

R=leafp@google.com

Review URL: https://codereview.chromium.org/1190413005.
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@vsmenon
vsmenon committed Jun 22, 2015
1 parent 9b1ad9c commit 4bb9fdc
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Showing 3 changed files with 190 additions and 115 deletions.
240 changes: 129 additions & 111 deletions pkg/dev_compiler/lib/src/checker/checker.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -337,7 +337,6 @@ class CodeChecker extends RecursiveAstVisitor {
final TypeRules _rules;
final CheckerReporter _reporter;
final _OverrideChecker _overrideChecker;
bool _constantContext = false;
bool _failure = false;
bool get failure => _failure || _overrideChecker._failure;

Expand All @@ -358,27 +357,6 @@ class CodeChecker extends RecursiveAstVisitor {
_rules.reportMissingType = callback;
}

_visitMaybeConst(AstNode n, visitNode(AstNode n)) {
var o = _constantContext;
if (!o) {
if (n is VariableDeclarationList) {
_constantContext = o || n.isConst;
} else if (n is VariableDeclaration) {
_constantContext = o || n.isConst;
} else if (n is DefaultFormalParameter) {
_constantContext = true;
} else if (n is FormalParameter) {
_constantContext = o || n.isConst;
} else if (n is InstanceCreationExpression) {
_constantContext = o || n.isConst;
} else if (n is ConstructorDeclaration) {
_constantContext = o || n.element.isConst;
}
}
visitNode(n);
_constantContext = o;
}

@override
void visitComment(Comment node) {
// skip, no need to do typechecking inside comments (they may contain
Expand Down Expand Up @@ -406,17 +384,15 @@ class CodeChecker extends RecursiveAstVisitor {
/// Check constructor declaration to ensure correct super call placement.
@override
void visitConstructorDeclaration(ConstructorDeclaration node) {
_visitMaybeConst(node, (node) {
node.visitChildren(this);

final init = node.initializers;
for (int i = 0, last = init.length - 1; i < last; i++) {
final node = init[i];
if (node is SuperConstructorInvocation) {
_recordMessage(new InvalidSuperInvocation(node));
}
node.visitChildren(this);

final init = node.initializers;
for (int i = 0, last = init.length - 1; i < last; i++) {
final node = init[i];
if (node is SuperConstructorInvocation) {
_recordMessage(new InvalidSuperInvocation(node));
}
});
}
}

@override
Expand Down Expand Up @@ -603,40 +579,94 @@ class CodeChecker extends RecursiveAstVisitor {
node.visitChildren(this);
}

AstNode _getOwnerFunction(AstNode node) {
var parent = node.parent;
while (parent is! FunctionExpression &&
parent is! MethodDeclaration &&
parent is! ConstructorDeclaration) {
parent = parent.parent;
DartType _getExpectedReturnType(FunctionBody body, bool yieldStar) {
FunctionType functionType;
var parent = body.parent;
if (parent is Declaration) {
functionType = _rules.elementType(parent.element);
} else {
assert(parent is FunctionExpression);
functionType = _rules.getStaticType(parent);
}
return parent;
}

FunctionType _getFunctionType(AstNode node) {
if (node is Declaration) {
return _rules.elementType(node.element);
var type = functionType.returnType;
var provider = _rules.provider;

InterfaceType expectedType = null;
if (body.isAsynchronous) {
if (body.isGenerator) {
// Stream<T> -> T
expectedType = provider.streamType;
} else {
// Future<T> -> T
// TODO(vsm): Revisit with issue #228.
expectedType = provider.futureType;
}
} else {
assert(node is FunctionExpression);
return _rules.getStaticType(node);
if (body.isGenerator) {
// Iterable<T> -> T
expectedType = provider.iterableType;
} else {
// T -> T
return type;
}
}
if (yieldStar) {
if (type.isDynamic) {
// Ensure it's at least a Stream / Iterable.
return expectedType.substitute4([provider.dynamicType]);
} else {
// Analyzer will provide a separate error if expected type
// is not compatible with type.
return type;
}
}
if (type.isDynamic) {
return type;
} else if (type is InterfaceType && type.element == expectedType.element) {
return type.typeArguments[0];
} else {
// Malformed type - fallback on analyzer error.
return null;
}
}

FunctionBody _getFunctionBody(AstNode node) {
while (node is! FunctionBody) {
node = node.parent;
}
return node as FunctionBody;
}

void _checkReturn(Expression expression, AstNode node) {
var type = _getFunctionType(_getOwnerFunction(node)).returnType;
void _checkReturnOrYield(Expression expression, AstNode node,
[bool yieldStar = false]) {
var body = _getFunctionBody(node);
var type = _getExpectedReturnType(body, yieldStar);
if (type == null) {
// We have a type mismatch: the async/async*/sync* modifier does
// not match the return or yield type. We should have already gotten an
// analyzer error in this case.
return;
}
// TODO(vsm): Enforce void or dynamic (to void?) when expression is null.
if (expression != null) checkAssignment(expression, type);
}

@override
void visitExpressionFunctionBody(ExpressionFunctionBody node) {
_checkReturn(node.expression, node);
_checkReturnOrYield(node.expression, node);
node.visitChildren(this);
}

@override
void visitReturnStatement(ReturnStatement node) {
_checkReturn(node.expression, node);
_checkReturnOrYield(node.expression, node);
node.visitChildren(this);
}

@override
void visitYieldStatement(YieldStatement node) {
_checkReturnOrYield(node.expression, node, node.star != null);
node.visitChildren(this);
}

Expand All @@ -660,24 +690,22 @@ class CodeChecker extends RecursiveAstVisitor {

@override
void visitDefaultFormalParameter(DefaultFormalParameter node) {
_visitMaybeConst(node, (node) {
// Check that defaults have the proper subtype.
var parameter = node.parameter;
var parameterType = _rules.elementType(parameter.element);
assert(parameterType != null);
var defaultValue = node.defaultValue;
if (defaultValue == null) {
if (_rules.maybeNonNullableType(parameterType)) {
var staticInfo = new InvalidVariableDeclaration(
_rules, node.identifier, parameterType);
_recordMessage(staticInfo);
}
} else {
checkAssignment(defaultValue, parameterType);
// Check that defaults have the proper subtype.
var parameter = node.parameter;
var parameterType = _rules.elementType(parameter.element);
assert(parameterType != null);
var defaultValue = node.defaultValue;
if (defaultValue == null) {
if (_rules.maybeNonNullableType(parameterType)) {
var staticInfo = new InvalidVariableDeclaration(
_rules, node.identifier, parameterType);
_recordMessage(staticInfo);
}
} else {
checkAssignment(defaultValue, parameterType);
}

node.visitChildren(this);
});
node.visitChildren(this);
}

@override
Expand All @@ -700,56 +728,47 @@ class CodeChecker extends RecursiveAstVisitor {

@override
void visitInstanceCreationExpression(InstanceCreationExpression node) {
_visitMaybeConst(node, (node) {
var arguments = node.argumentList;
var element = node.staticElement;
if (element != null) {
var type = _rules.elementType(node.staticElement);
checkArgumentList(arguments, type);
} else {
_recordMessage(new MissingTypeError(node));
}
node.visitChildren(this);
});
var arguments = node.argumentList;
var element = node.staticElement;
if (element != null) {
var type = _rules.elementType(node.staticElement);
checkArgumentList(arguments, type);
} else {
_recordMessage(new MissingTypeError(node));
}
node.visitChildren(this);
}

@override
void visitVariableDeclarationList(VariableDeclarationList node) {
_visitMaybeConst(node, (node) {
TypeName type = node.type;
if (type == null) {
// No checks are needed when the type is var. Although internally the
// typing rules may have inferred a more precise type for the variable
// based on the initializer.
} else {
var dartType = getType(type);
for (VariableDeclaration variable in node.variables) {
var initializer = variable.initializer;
if (initializer != null) {
checkAssignment(initializer, dartType);
} else if (_rules.maybeNonNullableType(dartType)) {
var element = variable.element;
if (element is FieldElement && !element.isStatic) {
// Initialized - possibly implicitly - during construction.
// Handle this via a runtime check during code generation.

// TODO(vsm): Detect statically whether this can fail and
// report a static error (must fail) or warning (can fail).
} else {
var staticInfo =
new InvalidVariableDeclaration(_rules, variable, dartType);
_recordMessage(staticInfo);
}
TypeName type = node.type;
if (type == null) {
// No checks are needed when the type is var. Although internally the
// typing rules may have inferred a more precise type for the variable
// based on the initializer.
} else {
var dartType = getType(type);
for (VariableDeclaration variable in node.variables) {
var initializer = variable.initializer;
if (initializer != null) {
checkAssignment(initializer, dartType);
} else if (_rules.maybeNonNullableType(dartType)) {
var element = variable.element;
if (element is FieldElement && !element.isStatic) {
// Initialized - possibly implicitly - during construction.
// Handle this via a runtime check during code generation.

// TODO(vsm): Detect statically whether this can fail and
// report a static error (must fail) or warning (can fail).
} else {
var staticInfo =
new InvalidVariableDeclaration(_rules, variable, dartType);
_recordMessage(staticInfo);
}
}
}
node.visitChildren(this);
});
}

@override
void visitVariableDeclaration(VariableDeclaration node) {
_visitMaybeConst(node, super.visitVariableDeclaration);
}
node.visitChildren(this);
}

void _checkRuntimeTypeCheck(AstNode node, TypeName typeName) {
Expand Down Expand Up @@ -885,7 +904,7 @@ class CodeChecker extends RecursiveAstVisitor {
if (expr is ParenthesizedExpression) {
checkAssignment(expr.expression, type);
} else {
_recordMessage(_rules.checkAssignment(expr, type, _constantContext));
_recordMessage(_rules.checkAssignment(expr, type));
}
}

Expand Down Expand Up @@ -956,8 +975,7 @@ class CodeChecker extends RecursiveAstVisitor {
// Check the rhs type
if (staticInfo is! CoercionInfo) {
var paramType = paramTypes.first;
staticInfo = _rules.checkAssignment(
expr.rightHandSide, paramType, _constantContext);
staticInfo = _rules.checkAssignment(expr.rightHandSide, paramType);
_recordMessage(staticInfo);
}
}
Expand Down
7 changes: 3 additions & 4 deletions pkg/dev_compiler/lib/src/checker/rules.dart
View file
Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ abstract class TypeRules {
bool isNonNullableType(DartType t) => false;
bool maybeNonNullableType(DartType t) => false;

StaticInfo checkAssignment(Expression expr, DartType t, bool constContext);
StaticInfo checkAssignment(Expression expr, DartType t);

DartType getStaticType(Expression expr) => expr.staticType;

Expand Down Expand Up @@ -93,8 +93,7 @@ class DartRules extends TypeRules {
return t1.isAssignableTo(t2);
}

StaticInfo checkAssignment(
Expression expr, DartType toType, bool constContext) {
StaticInfo checkAssignment(Expression expr, DartType toType) {
final fromType = getStaticType(expr);
if (!isAssignable(fromType, toType)) {
return new StaticTypeError(this, expr, toType);
Expand Down Expand Up @@ -444,7 +443,7 @@ class RestrictedRules extends TypeRules {
return Coercion.error();
}

StaticInfo checkAssignment(Expression expr, DartType toT, bool constContext) {
StaticInfo checkAssignment(Expression expr, DartType toT) {
final fromT = getStaticType(expr);
final Coercion c = _coerceTo(fromT, toT);
if (c is Identity) return null;
Expand Down
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