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Fix narrowing of property access expressions #8962

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Merged
ahejlsberg merged 3 commits into from
Jun 4, 2016
Merged

Fix narrowing of property access expressions #8962

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39c4e8a
Remove unnecessary restrictions in property access narrowing
ahejlsberg Jun 4, 2016
a5e9071
Fix fourslash test
ahejlsberg Jun 4, 2016
87ee72b
Add regression test
ahejlsberg Jun 4, 2016
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20 changes: 5 additions & 15 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -9991,24 +9991,14 @@ namespace ts {
}

const propType = getTypeOfSymbol(prop);
// Only compute control flow type if this is a property access expression that isn't an
// assignment target, and the referenced property was declared as a variable, property,
// accessor, or optional method.
if (node.kind !== SyntaxKind.PropertyAccessExpression || isAssignmentTarget(node) ||
!(propType.flags & TypeFlags.Union) && !(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor))) {
!(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor)) &&
!(prop.flags & SymbolFlags.Method && propType.flags & TypeFlags.Union)) {
return propType;
}
const leftmostNode = getLeftmostIdentifierOrThis(node);
if (!leftmostNode) {
return propType;
}
if (leftmostNode.kind === SyntaxKind.Identifier) {
const leftmostSymbol = getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(<Identifier>leftmostNode));
if (!leftmostSymbol) {
return propType;
}
const declaration = leftmostSymbol.valueDeclaration;
if (!declaration || declaration.kind !== SyntaxKind.VariableDeclaration && declaration.kind !== SyntaxKind.Parameter && declaration.kind !== SyntaxKind.BindingElement) {
return propType;
}
}
return getFlowTypeOfReference(node, propType, /*assumeInitialized*/ true, /*includeOuterFunctions*/ false);
}

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32 changes: 32 additions & 0 deletions tests/baselines/reference/classStaticPropertyTypeGuard.js
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@@ -0,0 +1,32 @@
//// [classStaticPropertyTypeGuard.ts]

// Repro from #8923

class A {
private static _a: string | undefined;

public get a(): string {
if (A._a) {
return A._a; // is possibly null or undefined.
}
return A._a = 'helloworld';
}
}

//// [classStaticPropertyTypeGuard.js]
// Repro from #8923
var A = (function () {
function A() {
}
Object.defineProperty(A.prototype, "a", {
get: function () {
if (A._a) {
return A._a; // is possibly null or undefined.
}
return A._a = 'helloworld';
},
enumerable: true,
configurable: true
});
return A;
}());
29 changes: 29 additions & 0 deletions tests/baselines/reference/classStaticPropertyTypeGuard.symbols
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@@ -0,0 +1,29 @@
=== tests/cases/compiler/classStaticPropertyTypeGuard.ts ===

// Repro from #8923

class A {
>A : Symbol(A, Decl(classStaticPropertyTypeGuard.ts, 0, 0))

private static _a: string | undefined;
>_a : Symbol(A._a, Decl(classStaticPropertyTypeGuard.ts, 3, 9))

public get a(): string {
>a : Symbol(A.a, Decl(classStaticPropertyTypeGuard.ts, 4, 42))

if (A._a) {
>A._a : Symbol(A._a, Decl(classStaticPropertyTypeGuard.ts, 3, 9))
>A : Symbol(A, Decl(classStaticPropertyTypeGuard.ts, 0, 0))
>_a : Symbol(A._a, Decl(classStaticPropertyTypeGuard.ts, 3, 9))

return A._a; // is possibly null or undefined.
>A._a : Symbol(A._a, Decl(classStaticPropertyTypeGuard.ts, 3, 9))
>A : Symbol(A, Decl(classStaticPropertyTypeGuard.ts, 0, 0))
>_a : Symbol(A._a, Decl(classStaticPropertyTypeGuard.ts, 3, 9))
}
return A._a = 'helloworld';
>A._a : Symbol(A._a, Decl(classStaticPropertyTypeGuard.ts, 3, 9))
>A : Symbol(A, Decl(classStaticPropertyTypeGuard.ts, 0, 0))
>_a : Symbol(A._a, Decl(classStaticPropertyTypeGuard.ts, 3, 9))
}
}
31 changes: 31 additions & 0 deletions tests/baselines/reference/classStaticPropertyTypeGuard.types
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@@ -0,0 +1,31 @@
=== tests/cases/compiler/classStaticPropertyTypeGuard.ts ===

// Repro from #8923

class A {
>A : A

private static _a: string | undefined;
>_a : string | undefined

public get a(): string {
>a : string

if (A._a) {
>A._a : string | undefined
>A : typeof A
>_a : string | undefined

return A._a; // is possibly null or undefined.
>A._a : string
>A : typeof A
>_a : string
}
return A._a = 'helloworld';
>A._a = 'helloworld' : string
>A._a : string | undefined
>A : typeof A
>_a : string | undefined
>'helloworld' : string
}
}
15 changes: 15 additions & 0 deletions tests/cases/compiler/classStaticPropertyTypeGuard.ts
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@@ -0,0 +1,15 @@
// @strictNullChecks: true
// @target: ES5

// Repro from #8923

class A {
private static _a: string | undefined;

public get a(): string {
if (A._a) {
return A._a; // is possibly null or undefined.
}
return A._a = 'helloworld';
}
}
34 changes: 23 additions & 11 deletions tests/cases/fourslash/quickInfoOnNarrowedTypeInModule.ts
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Expand Up @@ -50,14 +50,26 @@ goTo.marker('6');
verify.quickInfoIs('var m.exportedStrOrNum: string');
verify.completionListContains("exportedStrOrNum", "var m.exportedStrOrNum: string");

['7', '8', '9'].forEach((marker, index, arr) => {
goTo.marker(marker);
verify.quickInfoIs('var m.exportedStrOrNum: string | number');
verify.completionListContains("exportedStrOrNum", "var m.exportedStrOrNum: string | number");
});

['7', '8', '9'].forEach((marker, index, arr) => {
goTo.marker(marker);
verify.quickInfoIs('var m.exportedStrOrNum: string | number');
verify.memberListContains("exportedStrOrNum", "var m.exportedStrOrNum: string | number");
});
goTo.marker('7');
verify.quickInfoIs('var m.exportedStrOrNum: string | number');
verify.completionListContains("exportedStrOrNum", "var m.exportedStrOrNum: string | number");

goTo.marker('8');
verify.quickInfoIs('var m.exportedStrOrNum: number');
verify.completionListContains("exportedStrOrNum", "var m.exportedStrOrNum: number");

goTo.marker('9');
verify.quickInfoIs('var m.exportedStrOrNum: string');
verify.completionListContains("exportedStrOrNum", "var m.exportedStrOrNum: string");

goTo.marker('7');
verify.quickInfoIs('var m.exportedStrOrNum: string | number');
verify.memberListContains("exportedStrOrNum", "var m.exportedStrOrNum: string | number");

goTo.marker('8');
verify.quickInfoIs('var m.exportedStrOrNum: number');
verify.memberListContains("exportedStrOrNum", "var m.exportedStrOrNum: number");

goTo.marker('9');
verify.quickInfoIs('var m.exportedStrOrNum: string');
verify.memberListContains("exportedStrOrNum", "var m.exportedStrOrNum: string");