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Narrow on element access of literal #26424

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merged 7 commits into from
Aug 15, 2018
Merged

Narrow on element access of literal #26424

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2ab8989
Narrow literal element accesses
sandersn Aug 13, 2018
1902f30
Update baselines
sandersn Aug 13, 2018
964cebd
Cleanup
sandersn Aug 13, 2018
7f07bfe
More cleanup
sandersn Aug 13, 2018
567e323
Test dashes in property names
sandersn Aug 13, 2018
d142cbb
More cleanup
sandersn Aug 13, 2018
54353a0
Delete undead code
sandersn Aug 13, 2018
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11 changes: 7 additions & 4 deletions src/compiler/binder.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -723,6 +723,7 @@ namespace ts {
case SyntaxKind.Identifier:
case SyntaxKind.ThisKeyword:
case SyntaxKind.PropertyAccessExpression:
case SyntaxKind.ElementAccessExpression:
return isNarrowableReference(expr);
case SyntaxKind.CallExpression:
return hasNarrowableArgument(<CallExpression>expr);
Expand All @@ -737,10 +738,11 @@ namespace ts {
}

function isNarrowableReference(expr: Expression): boolean {
return expr.kind === SyntaxKind.Identifier ||
expr.kind === SyntaxKind.ThisKeyword ||
expr.kind === SyntaxKind.SuperKeyword ||
expr.kind === SyntaxKind.PropertyAccessExpression && isNarrowableReference((<PropertyAccessExpression>expr).expression);
return expr.kind === SyntaxKind.Identifier || expr.kind === SyntaxKind.ThisKeyword || expr.kind === SyntaxKind.SuperKeyword ||
isPropertyAccessExpression(expr) && isNarrowableReference(expr.expression) ||
isElementAccessExpression(expr) && expr.argumentExpression &&
(isStringLiteral(expr.argumentExpression) || isNumericLiteral(expr.argumentExpression)) &&
isNarrowableReference(expr.expression);
}

function hasNarrowableArgument(expr: CallExpression) {
Expand Down Expand Up @@ -2066,6 +2068,7 @@ namespace ts {
}
return checkStrictModeIdentifier(<Identifier>node);
case SyntaxKind.PropertyAccessExpression:
case SyntaxKind.ElementAccessExpression:
if (currentFlow && isNarrowableReference(<Expression>node)) {
node.flowNode = currentFlow;
}
Expand Down
54 changes: 39 additions & 15 deletions src/compiler/checker.ts
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Expand Up @@ -9155,7 +9155,8 @@ namespace ts {
getNodeLinks(accessNode!).resolvedSymbol = prop;
}
}
return getTypeOfSymbol(prop);
const propType = getTypeOfSymbol(prop);
return accessExpression ? getFlowTypeOfReference(accessExpression, propType) : propType;
}
if (isTupleType(objectType)) {
const restType = getRestTypeOfTupleType(objectType);
Expand Down Expand Up @@ -13767,9 +13768,10 @@ namespace ts {
case SyntaxKind.SuperKeyword:
return target.kind === SyntaxKind.SuperKeyword;
case SyntaxKind.PropertyAccessExpression:
return target.kind === SyntaxKind.PropertyAccessExpression &&
(<PropertyAccessExpression>source).name.escapedText === (<PropertyAccessExpression>target).name.escapedText &&
isMatchingReference((<PropertyAccessExpression>source).expression, (<PropertyAccessExpression>target).expression);
case SyntaxKind.ElementAccessExpression:
return (isPropertyAccessExpression(target) || isElementAccessExpression(target)) &&
getAccessedPropertyName(source as PropertyAccessExpression | ElementAccessExpression) === getAccessedPropertyName(target) &&
isMatchingReference((source as PropertyAccessExpression | ElementAccessExpression).expression, target.expression);
case SyntaxKind.BindingElement:
if (target.kind !== SyntaxKind.PropertyAccessExpression) return false;
const t = target as PropertyAccessExpression;
Expand All @@ -13785,6 +13787,12 @@ namespace ts {
return false;
}

function getAccessedPropertyName(access: PropertyAccessExpression | ElementAccessExpression): __String | undefined {
return isPropertyAccessExpression(access) ? access.name.escapedText :
isStringLiteral(access.argumentExpression) || isNumericLiteral(access.argumentExpression) ? escapeLeadingUnderscores(access.argumentExpression.text) :
undefined;
}

function containsMatchingReference(source: Node, target: Node) {
while (source.kind === SyntaxKind.PropertyAccessExpression) {
source = (<PropertyAccessExpression>source).expression;
Expand Down Expand Up @@ -14427,7 +14435,10 @@ namespace ts {
else if (flags & FlowFlags.Start) {
// Check if we should continue with the control flow of the containing function.
const container = (<FlowStart>flow).container;
if (container && container !== flowContainer && reference.kind !== SyntaxKind.PropertyAccessExpression && reference.kind !== SyntaxKind.ThisKeyword) {
if (container && container !== flowContainer &&
reference.kind !== SyntaxKind.PropertyAccessExpression &&
reference.kind !== SyntaxKind.ElementAccessExpression &&
reference.kind !== SyntaxKind.ThisKeyword) {
flow = container.flowNode!;
continue;
}
Expand Down Expand Up @@ -14544,7 +14555,10 @@ namespace ts {
type = narrowTypeBySwitchOnDiscriminant(type, flow.switchStatement, flow.clauseStart, flow.clauseEnd);
}
else if (isMatchingReferenceDiscriminant(expr, type)) {
type = narrowTypeByDiscriminant(type, <PropertyAccessExpression>expr, t => narrowTypeBySwitchOnDiscriminant(t, flow.switchStatement, flow.clauseStart, flow.clauseEnd));
type = narrowTypeByDiscriminant(
type,
expr as PropertyAccessExpression | ElementAccessExpression,
t => narrowTypeBySwitchOnDiscriminant(t, flow.switchStatement, flow.clauseStart, flow.clauseEnd));
}
return createFlowType(type, isIncomplete(flowType));
}
Expand Down Expand Up @@ -14660,14 +14674,23 @@ namespace ts {
}

function isMatchingReferenceDiscriminant(expr: Expression, computedType: Type) {
return expr.kind === SyntaxKind.PropertyAccessExpression &&
computedType.flags & TypeFlags.Union &&
isMatchingReference(reference, (<PropertyAccessExpression>expr).expression) &&
isDiscriminantProperty(computedType, (<PropertyAccessExpression>expr).name.escapedText);
if (!(computedType.flags & TypeFlags.Union) ||
expr.kind !== SyntaxKind.PropertyAccessExpression && expr.kind !== SyntaxKind.ElementAccessExpression) {
return false;
}
const access = expr as PropertyAccessExpression | ElementAccessExpression;
const name = getAccessedPropertyName(access);
if (!name) {
return false;
}
return isMatchingReference(reference, access.expression) && isDiscriminantProperty(computedType, name);
}

function narrowTypeByDiscriminant(type: Type, propAccess: PropertyAccessExpression, narrowType: (t: Type) => Type): Type {
const propName = propAccess.name.escapedText;
function narrowTypeByDiscriminant(type: Type, access: PropertyAccessExpression | ElementAccessExpression, narrowType: (t: Type) => Type): Type {
const propName = getAccessedPropertyName(access);
if (!propName) {
return type;
}
const propType = getTypeOfPropertyOfType(type, propName);
const narrowedPropType = propType && narrowType(propType);
return propType === narrowedPropType ? type : filterType(type, t => isTypeComparableTo(getTypeOfPropertyOfType(t, propName)!, narrowedPropType!));
Expand All @@ -14678,7 +14701,7 @@ namespace ts {
return getTypeWithFacts(type, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy);
}
if (isMatchingReferenceDiscriminant(expr, declaredType)) {
return narrowTypeByDiscriminant(type, <PropertyAccessExpression>expr, t => getTypeWithFacts(t, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy));
return narrowTypeByDiscriminant(type, <PropertyAccessExpression | ElementAccessExpression>expr, t => getTypeWithFacts(t, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy));
}
if (containsMatchingReferenceDiscriminant(reference, expr)) {
return declaredType;
Expand Down Expand Up @@ -14729,10 +14752,10 @@ namespace ts {
return narrowTypeByEquality(type, operator, left, assumeTrue);
}
if (isMatchingReferenceDiscriminant(left, declaredType)) {
return narrowTypeByDiscriminant(type, <PropertyAccessExpression>left, t => narrowTypeByEquality(t, operator, right, assumeTrue));
return narrowTypeByDiscriminant(type, <PropertyAccessExpression | ElementAccessExpression>left, t => narrowTypeByEquality(t, operator, right, assumeTrue));
}
if (isMatchingReferenceDiscriminant(right, declaredType)) {
return narrowTypeByDiscriminant(type, <PropertyAccessExpression>right, t => narrowTypeByEquality(t, operator, left, assumeTrue));
return narrowTypeByDiscriminant(type, <PropertyAccessExpression | ElementAccessExpression>right, t => narrowTypeByEquality(t, operator, left, assumeTrue));
}
if (containsMatchingReferenceDiscriminant(reference, left) || containsMatchingReferenceDiscriminant(reference, right)) {
return declaredType;
Expand Down Expand Up @@ -14971,6 +14994,7 @@ namespace ts {
case SyntaxKind.ThisKeyword:
case SyntaxKind.SuperKeyword:
case SyntaxKind.PropertyAccessExpression:
case SyntaxKind.ElementAccessExpression:
return narrowTypeByTruthiness(type, expr, assumeTrue);
case SyntaxKind.CallExpression:
return narrowTypeByTypePredicate(type, <CallExpression>expr, assumeTrue);
Expand Down
34 changes: 17 additions & 17 deletions tests/baselines/reference/constDeclarations-access3.types
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Expand Up @@ -135,9 +135,9 @@ M["x"] = 0;
var a = M.x + 1;
>a : number
>M.x + 1 : number
>M.x : number
>M.x : 0
>M : typeof M
>x : number
>x : 0
>1 : 1

function f(v: number) { }
Expand All @@ -147,43 +147,43 @@ function f(v: number) { }
f(M.x);
>f(M.x) : void
>f : (v: number) => void
>M.x : number
>M.x : 0
>M : typeof M
>x : number
>x : 0

if (M.x) { }
>M.x : number
>M.x : 0
>M : typeof M
>x : number
>x : 0

M.x;
>M.x : number
>M.x : 0
>M : typeof M
>x : number
>x : 0

(M.x);
>(M.x) : number
>M.x : number
>(M.x) : 0
>M.x : 0
>M : typeof M
>x : number
>x : 0

-M.x;
>-M.x : number
>M.x : number
>M.x : 0
>M : typeof M
>x : number
>x : 0

+M.x;
>+M.x : number
>M.x : number
>M.x : 0
>M : typeof M
>x : number
>x : 0

M.x.toString();
>M.x.toString() : string
>M.x.toString : (radix?: number) => string
>M.x : number
>M.x : 0
>M : typeof M
>x : number
>x : 0
>toString : (radix?: number) => string

34 changes: 17 additions & 17 deletions tests/baselines/reference/constDeclarations-access5.types
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Original file line number Diff line number Diff line change
Expand Up @@ -134,9 +134,9 @@ m["x"] = 0;
var a = m.x + 1;
>a : number
>m.x + 1 : number
>m.x : number
>m.x : 0
>m : typeof m
>x : number
>x : 0
>1 : 1

function f(v: number) { }
Expand All @@ -146,44 +146,44 @@ function f(v: number) { }
f(m.x);
>f(m.x) : void
>f : (v: number) => void
>m.x : number
>m.x : 0
>m : typeof m
>x : number
>x : 0

if (m.x) { }
>m.x : number
>m.x : 0
>m : typeof m
>x : number
>x : 0

m.x;
>m.x : number
>m.x : 0
>m : typeof m
>x : number
>x : 0

(m.x);
>(m.x) : number
>m.x : number
>(m.x) : 0
>m.x : 0
>m : typeof m
>x : number
>x : 0

-m.x;
>-m.x : number
>m.x : number
>m.x : 0
>m : typeof m
>x : number
>x : 0

+m.x;
>+m.x : number
>m.x : number
>m.x : 0
>m : typeof m
>x : number
>x : 0

m.x.toString();
>m.x.toString() : string
>m.x.toString : (radix?: number) => string
>m.x : number
>m.x : 0
>m : typeof m
>x : number
>x : 0
>toString : (radix?: number) => string

=== tests/cases/compiler/constDeclarations_access_1.ts ===
Expand Down