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Include 'undefined' in return type for implicit or expressionless returns

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This commit is contained in:
Anders Hejlsberg 2016-03-05 09:58:47 -08:00
parent eed4093be5
commit 2762772afd
1 changed files with 21 additions and 6 deletions
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27
src/compiler/checker.ts
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@ -6290,6 +6290,14 @@ namespace ts {
return true;
}
function getCombinedFlagsOfTypes(types: Type[]) {
let flags: TypeFlags = 0;
for (const t of types) {
flags |= t.flags;
}
return flags;
}
function getCommonSupertype(types: Type[]): Type {
if (!strictNullChecks) {
return forEach(types, t => isSupertypeOfEach(t, types) ? t : undefined);
@ -6299,7 +6307,7 @@ namespace ts {
return getUnionType(types);
}
const supertype = forEach(primaryTypes, t => isSupertypeOfEach(t, primaryTypes) ? t : undefined);
return supertype && addNullableKind(supertype, reduceLeft(types, (flags, t) => flags | t.flags, 0) & TypeFlags.Nullable);
return supertype && addNullableKind(supertype, getCombinedFlagsOfTypes(types) & TypeFlags.Nullable);
}
function reportNoCommonSupertypeError(types: Type[], errorLocation: Node, errorMessageChainHead: DiagnosticMessageChain): void {
@ -10931,7 +10939,8 @@ namespace ts {
}
}
else {
types = checkAndAggregateReturnExpressionTypes(<Block>func.body, contextualMapper, isAsync);
const hasImplicitReturn = !!(func.flags & NodeFlags.HasImplicitReturn);
types = checkAndAggregateReturnExpressionTypes(<Block>func.body, contextualMapper, isAsync, hasImplicitReturn);
if (types.length === 0) {
if (isAsync) {
// For an async function, the return type will not be void, but rather a Promise for void.
@ -11011,9 +11020,9 @@ namespace ts {
return aggregatedTypes;
}
function checkAndAggregateReturnExpressionTypes(body: Block, contextualMapper?: TypeMapper, isAsync?: boolean): Type[] {
function checkAndAggregateReturnExpressionTypes(body: Block, contextualMapper: TypeMapper, isAsync: boolean, hasImplicitReturn: boolean): Type[] {
const aggregatedTypes: Type[] = [];
let hasOmittedExpressions = false;
forEachReturnStatement(body, returnStatement => {
const expr = returnStatement.expression;
if (expr) {
@ -11025,13 +11034,19 @@ namespace ts {
// the native Promise<T> type by the caller.
type = checkAwaitedType(type, body.parent, Diagnostics.Return_expression_in_async_function_does_not_have_a_valid_callable_then_member);
}
if (!contains(aggregatedTypes, type)) {
aggregatedTypes.push(type);
}
}
else {
hasOmittedExpressions = true;
}
});
if (strictNullChecks && aggregatedTypes.length && (hasOmittedExpressions || hasImplicitReturn)) {
if (!contains(aggregatedTypes, undefinedType)) {
aggregatedTypes.push(undefinedType);
}
}
return aggregatedTypes;
}