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This commit is contained in:
Anders Hejlsberg 2019-10-19 07:04:24 -07:00
parent 98fe34225c
commit 60b391507e
1 changed files with 16 additions and 11 deletions
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27
src/compiler/checker.ts
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@ -19187,13 +19187,18 @@ namespace ts {
type = narrowBySwitchOnTypeOf(type, flow.switchStatement, flow.clauseStart, flow.clauseEnd);
}
else {
if (strictNullChecks && optionalChainContainsReference(expr, reference)) {
type = narrowTypeBySwitchOptionalChainContainment(type, flow.switchStatement, flow.clauseStart, flow.clauseEnd);
if (strictNullChecks) {
if (optionalChainContainsReference(expr, reference)) {
type = narrowTypeBySwitchOptionalChainContainment(type, flow.switchStatement, flow.clauseStart, flow.clauseEnd,
t => !(t.flags & (TypeFlags.Undefined | TypeFlags.Never)));
}
else if (expr.kind === SyntaxKind.TypeOfExpression && optionalChainContainsReference((expr as TypeOfExpression).expression, reference)) {
type = narrowTypeBySwitchOptionalChainContainment(type, flow.switchStatement, flow.clauseStart, flow.clauseEnd,
t => !(t.flags & TypeFlags.Never || t.flags & TypeFlags.StringLiteral && (<StringLiteralType>t).value === "undefined"));
}
}
if (isMatchingReferenceDiscriminant(expr, type)) {
type = narrowTypeByDiscriminant(
type,
expr as AccessExpression,
type = narrowTypeByDiscriminant(type, expr as AccessExpression,
t => narrowTypeBySwitchOnDiscriminant(t, flow.switchStatement, flow.clauseStart, flow.clauseEnd));
}
else if (containsMatchingReferenceDiscriminant(reference, expr)) {
@ -19539,10 +19544,9 @@ namespace ts {
}
}
function narrowTypeBySwitchOptionalChainContainment(type: Type, switchStatement: SwitchStatement, clauseStart: number, clauseEnd: number) {
const noClauseIsDefaultOrUndefined = clauseStart !== clauseEnd &&
every(getSwitchClauseTypes(switchStatement).slice(clauseStart, clauseEnd), t => !(t.flags & (TypeFlags.Undefined | TypeFlags.Never)));
return noClauseIsDefaultOrUndefined ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type;
function narrowTypeBySwitchOptionalChainContainment(type: Type, switchStatement: SwitchStatement, clauseStart: number, clauseEnd: number, clauseCheck: (type: Type) => boolean) {
const everyClauseChecks = clauseStart !== clauseEnd && every(getSwitchClauseTypes(switchStatement).slice(clauseStart, clauseEnd), clauseCheck);
return everyClauseChecks ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type;
}
function narrowTypeBySwitchOnDiscriminant(type: Type, switchStatement: SwitchStatement, clauseStart: number, clauseEnd: number) {
@ -19771,8 +19775,9 @@ namespace ts {
if (isMatchingReference(reference, predicateArgument)) {
return getNarrowedType(type, predicate.type, assumeTrue, isTypeSubtypeOf);
}
if (strictNullChecks && assumeTrue && !(getTypeFacts(predicate.type) & TypeFacts.EQUndefined)) {
type = getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull);
if (strictNullChecks && assumeTrue && optionalChainContainsReference(predicateArgument, reference) &&
!(getTypeFacts(predicate.type) & TypeFacts.EQUndefined)) {
return getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull);
}
if (containsMatchingReference(reference, predicateArgument)) {
return declaredType;