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Assignability checking for yield and yield* expressions

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This commit is contained in:
Jason Freeman 2015-04-27 17:01:10 -07:00
parent 623507c0f2
commit 95bfd7c376
1 changed files with 22 additions and 2 deletions
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24
src/compiler/checker.ts
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@ -7905,6 +7905,26 @@ module ts {
grammarErrorOnFirstToken(node, Diagnostics.A_yield_expression_is_only_allowed_in_a_generator_declaration);
}
if (node.expression) {
let func = getContainingFunction(node);
// If this is correct code, the func should always have a star. After all,
// we are in a yield context.
// Also, there is no point in doing an assignability check if the function
// has no explicit return type, because the return type is directly computed
// from the yield expressions.
if (func.asteriskToken && func.type) {
let signatureElementType = getElementTypeFromIterableIterator(getTypeFromTypeNode(func.type), /*errorNode*/ undefined) || unknownType;
let expressionType = checkExpressionCached(node.expression, /*contextualMapper*/ undefined);
if (node.asteriskToken) {
let expressionElementType = checkIteratedType(expressionType, node.expression);
checkTypeAssignableTo(expressionElementType, signatureElementType, node.expression, /*headMessage*/ undefined);
}
else {
checkTypeAssignableTo(expressionType, signatureElementType, node.expression, /*headMessage*/ undefined);
}
}
}
// Both yield and yield* expressions are any
return anyType;
}
@ -9480,7 +9500,7 @@ module ts {
}
if (languageVersion >= ScriptTarget.ES6) {
return checkIteratedType(inputType, errorNode) || anyType;
return checkIteratedType(inputType, errorNode);
}
if (allowStringInput) {
@ -9509,7 +9529,7 @@ module ts {
checkTypeAssignableTo(iterable, createIterableType(elementType), errorNode);
}
return elementType;
return elementType || anyType;
}
function getElementTypeFromIterable(iterable: Type, errorNode: Node): Type {