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Check destructuring validity the same way element accesses and indexed accesses are checked #24700

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merged 6 commits into from
Nov 1, 2018
Merged

Check destructuring validity the same way element accesses and indexed accesses are checked #24700

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26b3665
Check destructuring validity the same way element accesses and indexe…
weswigham Jun 5, 2018
e2b492a
Merge branch 'master' into generic-mapped-destructuring
weswigham Sep 6, 2018
5b900c7
Merge branch 'master' into generic-mapped-destructuring
weswigham Oct 31, 2018
d933812
Accept updated test baseline
weswigham Oct 31, 2018
8250384
Use raw apparent type instead of passing in flag to sometimes make one
weswigham Oct 31, 2018
96ad54c
Use `checkComputedPropertyName`
weswigham Nov 1, 2018
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92 changes: 35 additions & 57 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -4635,6 +4635,10 @@ namespace ts {
if (isTypeAny(parentType)) {
return parentType;
}
// Relax null check on ambient destructuring parameters, since the parameters have no implementation and are just documentation
if (strictNullChecks && declaration.flags & NodeFlags.Ambient && isParameterDeclaration(declaration)) {
parentType = getNonNullableType(parentType);
}

let type: Type | undefined;
if (pattern.kind === SyntaxKind.ObjectBindingPattern) {
Expand All @@ -4654,53 +4658,13 @@ namespace ts {
else {
// Use explicitly specified property name ({ p: xxx } form), or otherwise the implied name ({ p } form)
const name = declaration.propertyName || <Identifier>declaration.name;
const isLate = isLateBindableName(name);
const isWellKnown = isComputedPropertyName(name) && isWellKnownSymbolSyntactically(name.expression);
if (!isLate && !isWellKnown && isComputedNonLiteralName(name)) {
const exprType = checkExpression((name as ComputedPropertyName).expression);
if (isTypeAssignableToKind(exprType, TypeFlags.ESSymbolLike)) {
if (noImplicitAny) {
error(declaration, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(exprType), typeToString(parentType));
}
return anyType;
}
const indexerType = isTypeAssignableToKind(exprType, TypeFlags.NumberLike) && getIndexTypeOfType(parentType, IndexKind.Number) || getIndexTypeOfType(parentType, IndexKind.String);
if (!indexerType && noImplicitAny && !compilerOptions.suppressImplicitAnyIndexErrors) {
if (getIndexTypeOfType(parentType, IndexKind.Number)) {
error(declaration, Diagnostics.Element_implicitly_has_an_any_type_because_index_expression_is_not_of_type_number);
}
else {
error(declaration, Diagnostics.Element_implicitly_has_an_any_type_because_type_0_has_no_index_signature, typeToString(parentType));
}
}
return indexerType || anyType;
}

// Use type of the specified property, or otherwise, for a numeric name, the type of the numeric index signature,
// or otherwise the type of the string index signature.
const nameType = isLate ? checkComputedPropertyName(name as ComputedPropertyName) as LiteralType | UniqueESSymbolType : undefined;
const text = isLate ? getLateBoundNameFromType(nameType!) :
isWellKnown ? getPropertyNameForKnownSymbolName(idText(((name as ComputedPropertyName).expression as PropertyAccessExpression).name)) :
getTextOfPropertyName(name);

// Relax null check on ambient destructuring parameters, since the parameters have no implementation and are just documentation
if (strictNullChecks && declaration.flags & NodeFlags.Ambient && isParameterDeclaration(declaration)) {
parentType = getNonNullableType(parentType);
}
if (isLate && nameType && !getPropertyOfType(parentType, text) && isTypeAssignableToKind(nameType, TypeFlags.ESSymbolLike)) {
if (noImplicitAny) {
error(declaration, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(nameType), typeToString(parentType));
}
return anyType;
}
const declaredType = getConstraintForLocation(getTypeOfPropertyOfType(parentType, text), declaration.name);
type = declaredType && getFlowTypeOfReference(declaration, declaredType) ||
isNumericLiteralName(text) && getIndexTypeOfType(parentType, IndexKind.Number) ||
getIndexTypeOfType(parentType, IndexKind.String);
if (!type) {
error(name, Diagnostics.Type_0_has_no_property_1_and_no_string_index_signature, typeToString(parentType), declarationNameToString(name));
return errorType;
}
const exprType = isComputedPropertyName(name)
? checkExpression(name.expression)
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Use checkComputedPropertyName here.

: isIdentifier(name)
? getLiteralType(unescapeLeadingUnderscores(name.escapedText))
: checkExpression(name);
const declaredType = checkIndexedAccessIndexType(getIndexedAccessType(getApparentType(parentType), exprType, name), name);
type = getFlowTypeOfReference(declaration, getConstraintForLocation(declaredType, declaration.name));
}
}
else {
Expand Down Expand Up @@ -9359,12 +9323,16 @@ namespace ts {
return false;
}

function getPropertyTypeForIndexType(objectType: Type, indexType: Type, accessNode: ElementAccessExpression | IndexedAccessTypeNode | undefined, cacheSymbol: boolean, missingType: Type) {
function getPropertyTypeForIndexType(objectType: Type, indexType: Type, accessNode: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | undefined, cacheSymbol: boolean, missingType: Type) {
const accessExpression = accessNode && accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode : undefined;
const propName = isTypeUsableAsLateBoundName(indexType) ? getLateBoundNameFromType(indexType) :
accessExpression && checkThatExpressionIsProperSymbolReference(accessExpression.argumentExpression, indexType, /*reportError*/ false) ?
getPropertyNameForKnownSymbolName(idText((<PropertyAccessExpression>accessExpression.argumentExpression).name)) :
undefined;
const propName = isTypeUsableAsLateBoundName(indexType)
? getLateBoundNameFromType(indexType)
: accessExpression && checkThatExpressionIsProperSymbolReference(accessExpression.argumentExpression, indexType, /*reportError*/ false)
? getPropertyNameForKnownSymbolName(idText((<PropertyAccessExpression>accessExpression.argumentExpression).name))
: accessNode && isPropertyName(accessNode)
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I don't think you need this case.

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Needed to handle well-known symbol names, which are not normal property names or unique symbols:

let { [Symbol.iterator]: destructured } = []

// late bound names are handled in the first branch, so here we only need to handle normal names
? getPropertyNameForPropertyNameNode(accessNode)
: undefined;
if (propName !== undefined) {
const prop = getPropertyOfType(objectType, propName);
if (prop) {
Expand All @@ -9385,7 +9353,7 @@ namespace ts {
}
if (everyType(objectType, isTupleType) && isNumericLiteralName(propName) && +propName >= 0) {
if (accessNode && everyType(objectType, t => !(<TupleTypeReference>t).target.hasRestElement)) {
const indexNode = accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode.argumentExpression : accessNode.indexType;
const indexNode = getIndexNodeForAccessExpression(accessNode);
error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(propName), typeToString(objectType));
}
return mapType(objectType, t => getRestTypeOfTupleType(<TupleTypeReference>t) || undefinedType);
Expand All @@ -9400,7 +9368,7 @@ namespace ts {
undefined;
if (indexInfo) {
if (accessNode && !isTypeAssignableToKind(indexType, TypeFlags.String | TypeFlags.Number)) {
const indexNode = accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode.argumentExpression : accessNode.indexType;
const indexNode = getIndexNodeForAccessExpression(accessNode);
error(indexNode, Diagnostics.Type_0_cannot_be_used_as_an_index_type, typeToString(indexType));
}
else if (accessExpression && indexInfo.isReadonly && (isAssignmentTarget(accessExpression) || isDeleteTarget(accessExpression))) {
Expand Down Expand Up @@ -9441,7 +9409,7 @@ namespace ts {
return anyType;
}
if (accessNode) {
const indexNode = accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode.argumentExpression : accessNode.indexType;
const indexNode = getIndexNodeForAccessExpression(accessNode);
if (indexType.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) {
error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, "" + (<LiteralType>indexType).value, typeToString(objectType));
}
Expand All @@ -9458,6 +9426,16 @@ namespace ts {
return missingType;
}

function getIndexNodeForAccessExpression(accessNode: ElementAccessExpression | IndexedAccessTypeNode | PropertyName) {
return accessNode.kind === SyntaxKind.ElementAccessExpression
? accessNode.argumentExpression
: accessNode.kind === SyntaxKind.IndexedAccessType
? accessNode.indexType
: accessNode.kind === SyntaxKind.ComputedPropertyName
? accessNode.expression
: accessNode;
}

function isGenericObjectType(type: Type): boolean {
return maybeTypeOfKind(type, TypeFlags.InstantiableNonPrimitive | TypeFlags.GenericMappedType);
}
Expand Down Expand Up @@ -9521,7 +9499,7 @@ namespace ts {
return instantiateType(getTemplateTypeFromMappedType(objectType), templateMapper);
}

function getIndexedAccessType(objectType: Type, indexType: Type, accessNode?: ElementAccessExpression | IndexedAccessTypeNode, missingType = accessNode ? errorType : unknownType): Type {
function getIndexedAccessType(objectType: Type, indexType: Type, accessNode?: ElementAccessExpression | IndexedAccessTypeNode | PropertyName, missingType = accessNode ? errorType : unknownType): Type {
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No extra flag please.

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It's now gone, and I'm using the raw apparent type as the input directly instead. The downside is that error messages now reference the apparent type instead of the original type, too.

if (objectType === wildcardType || indexType === wildcardType) {
return wildcardType;
}
Expand Down Expand Up @@ -23205,7 +23183,7 @@ namespace ts {
forEach(node.types, checkSourceElement);
}

function checkIndexedAccessIndexType(type: Type, accessNode: ElementAccessExpression | IndexedAccessTypeNode) {
function checkIndexedAccessIndexType(type: Type, accessNode: Node) {
if (!(type.flags & TypeFlags.IndexedAccess)) {
return type;
}
Expand Down
8 changes: 4 additions & 4 deletions tests/baselines/reference/ES5For-of27.errors.txt
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Original file line number Diff line number Diff line change
@@ -1,13 +1,13 @@
tests/cases/conformance/statements/for-ofStatements/ES5For-of27.ts(1,11): error TS2459: Type 'number' has no property 'x' and no string index signature.
tests/cases/conformance/statements/for-ofStatements/ES5For-of27.ts(1,21): error TS2459: Type 'number' has no property 'y' and no string index signature.
tests/cases/conformance/statements/for-ofStatements/ES5For-of27.ts(1,11): error TS2339: Property 'x' does not exist on type 'Number'.
tests/cases/conformance/statements/for-ofStatements/ES5For-of27.ts(1,21): error TS2339: Property 'y' does not exist on type 'Number'.


==== tests/cases/conformance/statements/for-ofStatements/ES5For-of27.ts (2 errors) ====
for (var {x: a = 0, y: b = 1} of [2, 3]) {
~
!!! error TS2459: Type 'number' has no property 'x' and no string index signature.
!!! error TS2339: Property 'x' does not exist on type 'Number'.
~
!!! error TS2459: Type 'number' has no property 'y' and no string index signature.
!!! error TS2339: Property 'y' does not exist on type 'Number'.
a;
b;
}
8 changes: 4 additions & 4 deletions tests/baselines/reference/ES5For-of29.errors.txt
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@@ -1,13 +1,13 @@
tests/cases/conformance/statements/for-ofStatements/ES5For-of29.ts(1,13): error TS2459: Type 'number' has no property 'x' and no string index signature.
tests/cases/conformance/statements/for-ofStatements/ES5For-of29.ts(1,23): error TS2459: Type 'number' has no property 'y' and no string index signature.
tests/cases/conformance/statements/for-ofStatements/ES5For-of29.ts(1,13): error TS2339: Property 'x' does not exist on type 'Number'.
tests/cases/conformance/statements/for-ofStatements/ES5For-of29.ts(1,23): error TS2339: Property 'y' does not exist on type 'Number'.


==== tests/cases/conformance/statements/for-ofStatements/ES5For-of29.ts (2 errors) ====
for (const {x: a = 0, y: b = 1} of [2, 3]) {
~
!!! error TS2459: Type 'number' has no property 'x' and no string index signature.
!!! error TS2339: Property 'x' does not exist on type 'Number'.
~
!!! error TS2459: Type 'number' has no property 'y' and no string index signature.
!!! error TS2339: Property 'y' does not exist on type 'Number'.
a;
b;
}
8 changes: 4 additions & 4 deletions tests/baselines/reference/ES5For-of35.errors.txt
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Original file line number Diff line number Diff line change
@@ -1,13 +1,13 @@
tests/cases/conformance/statements/for-ofStatements/ES5For-of35.ts(1,13): error TS2459: Type 'number' has no property 'x' and no string index signature.
tests/cases/conformance/statements/for-ofStatements/ES5For-of35.ts(1,23): error TS2459: Type 'number' has no property 'y' and no string index signature.
tests/cases/conformance/statements/for-ofStatements/ES5For-of35.ts(1,13): error TS2339: Property 'x' does not exist on type 'Number'.
tests/cases/conformance/statements/for-ofStatements/ES5For-of35.ts(1,23): error TS2339: Property 'y' does not exist on type 'Number'.


==== tests/cases/conformance/statements/for-ofStatements/ES5For-of35.ts (2 errors) ====
for (const {x: a = 0, y: b = 1} of [2, 3]) {
~
!!! error TS2459: Type 'number' has no property 'x' and no string index signature.
!!! error TS2339: Property 'x' does not exist on type 'Number'.
~
!!! error TS2459: Type 'number' has no property 'y' and no string index signature.
!!! error TS2339: Property 'y' does not exist on type 'Number'.
a;
b;
}
13 changes: 11 additions & 2 deletions tests/baselines/reference/blockScopedBindingUsedBeforeDef.errors.txt
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@@ -1,23 +1,32 @@
tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts(2,12): error TS2448: Block-scoped variable 'a' used before its declaration.
tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts(2,12): error TS2538: Type 'any' cannot be used as an index type.
tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts(5,12): error TS2448: Block-scoped variable 'a' used before its declaration.
tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts(5,12): error TS2538: Type 'any' cannot be used as an index type.
tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts(8,7): error TS2448: Block-scoped variable 'b' used before its declaration.
tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts(8,7): error TS2538: Type 'any' cannot be used as an index type.


==== tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts (3 errors) ====
==== tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts (6 errors) ====
// 1:
for (let {[a]: a} of [{ }]) continue;
~
!!! error TS2448: Block-scoped variable 'a' used before its declaration.
!!! related TS2728 tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts:2:16: 'a' is declared here.
~
!!! error TS2538: Type 'any' cannot be used as an index type.
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This doesn't feel like a legal error, but it seems like we're only issuing it when there's already an error on the same node. Is there an issue with the error type leaking out into an error message?

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Most certainly. It's because we choose to consider indexing with any an error today (esp. if the thing being indexed has no index signatures), but destructuring accesses don't flag that right now. This PR aligns them.


// 2:
for (let {[a]: a} = { }; false; ) continue;
~
!!! error TS2448: Block-scoped variable 'a' used before its declaration.
!!! related TS2728 tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts:5:16: 'a' is declared here.
~
!!! error TS2538: Type 'any' cannot be used as an index type.

// 3:
let {[b]: b} = { };
~
!!! error TS2448: Block-scoped variable 'b' used before its declaration.
!!! related TS2728 tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts:8:11: 'b' is declared here.
!!! related TS2728 tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts:8:11: 'b' is declared here.
~
!!! error TS2538: Type 'any' cannot be used as an index type.
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