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Fix #16778 - use previous type and not declared type (#17381)

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* Fix #16778 - use previous type to check discriminable type and not declared type

* Rename prevType -> computedType
This commit is contained in:
Wesley Wigham
2017-07-26 15:27:02 -07:00
committed by GitHub
parent b9fe9964d2
commit b080aa9440
5 changed files with 300 additions and 7 deletions
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14
src/compiler/checker.ts
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@@ -11500,7 +11500,7 @@ namespace ts {
if (isMatchingReference(reference, expr)) {
type = narrowTypeBySwitchOnDiscriminant(type, flow.switchStatement, flow.clauseStart, flow.clauseEnd);
}
else if (isMatchingReferenceDiscriminant(expr)) {
else if (isMatchingReferenceDiscriminant(expr, type)) {
type = narrowTypeByDiscriminant(type, <PropertyAccessExpression>expr, t => narrowTypeBySwitchOnDiscriminant(t, flow.switchStatement, flow.clauseStart, flow.clauseEnd));
}
return createFlowType(type, isIncomplete(flowType));
@@ -11620,11 +11620,11 @@ namespace ts {
return result;
}
function isMatchingReferenceDiscriminant(expr: Expression) {
function isMatchingReferenceDiscriminant(expr: Expression, computedType: Type) {
return expr.kind === SyntaxKind.PropertyAccessExpression &&
declaredType.flags & TypeFlags.Union &&
computedType.flags & TypeFlags.Union &&
isMatchingReference(reference, (<PropertyAccessExpression>expr).expression) &&
isDiscriminantProperty(declaredType, (<PropertyAccessExpression>expr).name.escapedText);
isDiscriminantProperty(computedType, (<PropertyAccessExpression>expr).name.escapedText);
}
function narrowTypeByDiscriminant(type: Type, propAccess: PropertyAccessExpression, narrowType: (t: Type) => Type): Type {
@@ -11638,7 +11638,7 @@ namespace ts {
if (isMatchingReference(reference, expr)) {
return getTypeWithFacts(type, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy);
}
if (isMatchingReferenceDiscriminant(expr)) {
if (isMatchingReferenceDiscriminant(expr, declaredType)) {
return narrowTypeByDiscriminant(type, <PropertyAccessExpression>expr, t => getTypeWithFacts(t, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy));
}
if (containsMatchingReferenceDiscriminant(reference, expr)) {
@@ -11670,10 +11670,10 @@ namespace ts {
if (isMatchingReference(reference, right)) {
return narrowTypeByEquality(type, operator, left, assumeTrue);
}
if (isMatchingReferenceDiscriminant(left)) {
if (isMatchingReferenceDiscriminant(left, declaredType)) {
return narrowTypeByDiscriminant(type, <PropertyAccessExpression>left, t => narrowTypeByEquality(t, operator, right, assumeTrue));
}
if (isMatchingReferenceDiscriminant(right)) {
if (isMatchingReferenceDiscriminant(right, declaredType)) {
return narrowTypeByDiscriminant(type, <PropertyAccessExpression>right, t => narrowTypeByEquality(t, operator, left, assumeTrue));
}
if (containsMatchingReferenceDiscriminant(reference, left) || containsMatchingReferenceDiscriminant(reference, right)) {