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Remove undefined from the type of default initialised parameters when narrowing #14498

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Merged
merged 6 commits into from
Mar 7, 2017
Merged

Remove undefined from the type of default initialised parameters when narrowing #14498

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eaca169
Remove optionality from the initial type of default-valued parameters
sandersn Mar 7, 2017
533ce82
Add assignability tests for initialised parameters
sandersn Mar 7, 2017
36513f2
Remove only undefined, not null | undefined, from declared type
sandersn Mar 7, 2017
2325fda
Move isFlowNarrowable call inside getFlowTypeOfReference
sandersn Mar 7, 2017
c1f4c9c
Update baselines
sandersn Mar 7, 2017
24c8de2
Inline isFlowNarrowable
sandersn Mar 7, 2017
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43 changes: 22 additions & 21 deletions src/compiler/checker.ts
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Expand Up @@ -3368,16 +3368,6 @@ namespace ts {
return strictNullChecks && optional ? includeFalsyTypes(type, TypeFlags.Undefined) : type;
}

/** remove undefined from the annotated type of a parameter when there is an initializer (that doesn't include undefined) */
function removeOptionalityFromAnnotation(annotatedType: Type, declaration: VariableLikeDeclaration): Type {
const annotationIncludesUndefined = strictNullChecks &&
declaration.kind === SyntaxKind.Parameter &&
declaration.initializer &&
getFalsyFlags(annotatedType) & TypeFlags.Undefined &&
!(getFalsyFlags(checkExpression(declaration.initializer)) & TypeFlags.Undefined);
return annotationIncludesUndefined ? getNonNullableType(annotatedType) : annotatedType;
}

// Return the inferred type for a variable, parameter, or property declaration
function getTypeForVariableLikeDeclaration(declaration: VariableLikeDeclaration, includeOptionality: boolean): Type {
if (declaration.flags & NodeFlags.JavaScriptFile) {
Expand Down Expand Up @@ -3412,7 +3402,7 @@ namespace ts {

// Use type from type annotation if one is present
if (declaration.type) {
const declaredType = removeOptionalityFromAnnotation(getTypeFromTypeNode(declaration.type), declaration);
const declaredType = getTypeFromTypeNode(declaration.type);
return addOptionality(declaredType, /*optional*/ declaration.questionToken && includeOptionality);
}

Expand Down Expand Up @@ -10248,14 +10238,12 @@ namespace ts {
return false;
}

function getFlowTypeOfReference(reference: Node, declaredType: Type, assumeInitialized: boolean, flowContainer: Node) {
function isFlowNarrowable(reference: Node, type: Type, couldBeUninitialized?: boolean) {
return reference.flowNode && (type.flags & TypeFlags.Narrowable || couldBeUninitialized);
}

function getFlowTypeOfReference(reference: Node, declaredType: Type, initialType = declaredType, flowContainer?: Node) {
let key: string;
if (!reference.flowNode || assumeInitialized && !(declaredType.flags & TypeFlags.Narrowable)) {
return declaredType;
}
const initialType = assumeInitialized ? declaredType :
declaredType === autoType || declaredType === autoArrayType ? undefinedType :
includeFalsyTypes(declaredType, TypeFlags.Undefined);
const visitedFlowStart = visitedFlowCount;
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Just inline the function here. It's not called anywhere else best I can tell.

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Done

const evolvedType = getTypeFromFlowType(getTypeAtFlowNode(reference.flowNode));
visitedFlowCount = visitedFlowStart;
Expand Down Expand Up @@ -10934,6 +10922,16 @@ namespace ts {
return symbol.flags & SymbolFlags.Variable && (getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Const) !== 0 && getTypeOfSymbol(symbol) !== autoArrayType;
}

/** remove undefined from the annotated type of a parameter when there is an initializer (that doesn't include undefined) */
function removeOptionalityFromDeclaredType(declaredType: Type, declaration: VariableLikeDeclaration): Type {
const annotationIncludesUndefined = strictNullChecks &&
declaration.kind === SyntaxKind.Parameter &&
declaration.initializer &&
getFalsyFlags(declaredType) & TypeFlags.Undefined &&
!(getFalsyFlags(checkExpression(declaration.initializer)) & TypeFlags.Undefined);
return annotationIncludesUndefined ? getNonNullableType(declaredType) : declaredType;
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This line is the source if the issue with null I mentioned. It removes both undefined and null. You need to use getTypeWithFacts(declaredType, TypeFacts.NEUndefined) instead.

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This is the cause of #14236.

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Done

}

function checkIdentifier(node: Identifier): Type {
const symbol = getResolvedSymbol(node);
if (symbol === unknownSymbol) {
Expand Down Expand Up @@ -11052,7 +11050,10 @@ namespace ts {
const assumeInitialized = isParameter || isOuterVariable ||
type !== autoType && type !== autoArrayType && (!strictNullChecks || (type.flags & TypeFlags.Any) !== 0 || isInTypeQuery(node)) ||
isInAmbientContext(declaration);
const flowType = getFlowTypeOfReference(node, type, assumeInitialized, flowContainer);
const initialType = assumeInitialized ? (isParameter ? removeOptionalityFromDeclaredType(type, getRootDeclaration(declaration) as VariableLikeDeclaration) : type) :
type === autoType || type === autoArrayType ? undefinedType :
includeFalsyTypes(type, TypeFlags.Undefined);
const flowType = isFlowNarrowable(node, type, !assumeInitialized) ? getFlowTypeOfReference(node, type, initialType, flowContainer) : type;
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I would keep the isFlowNarrowable logic inside getFlowTypeOfReference, even if it means adding another parameter. Otherwise, you have to always write this combined pattern which is even more complicated.

// A variable is considered uninitialized when it is possible to analyze the entire control flow graph
// from declaration to use, and when the variable's declared type doesn't include undefined but the
// control flow based type does include undefined.
Expand Down Expand Up @@ -11318,7 +11319,7 @@ namespace ts {
if (isClassLike(container.parent)) {
const symbol = getSymbolOfNode(container.parent);
const type = hasModifier(container, ModifierFlags.Static) ? getTypeOfSymbol(symbol) : (<InterfaceType>getDeclaredTypeOfSymbol(symbol)).thisType;
return getFlowTypeOfReference(node, type, /*assumeInitialized*/ true, /*flowContainer*/ undefined);
return isFlowNarrowable(node, type) ? getFlowTypeOfReference(node, type) : type;
}

if (isInJavaScriptFile(node)) {
Expand Down Expand Up @@ -13309,7 +13310,7 @@ namespace ts {
!(prop.flags & SymbolFlags.Method && propType.flags & TypeFlags.Union)) {
return propType;
}
const flowType = getFlowTypeOfReference(node, propType, /*assumeInitialized*/ true, /*flowContainer*/ undefined);
const flowType = isFlowNarrowable(node, propType) ? getFlowTypeOfReference(node, propType) : propType;
return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType;
}

Expand Down
4 changes: 4 additions & 0 deletions tests/baselines/reference/defaultParameterAddsUndefinedWithStrictNullChecks.js
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Expand Up @@ -18,10 +18,12 @@ function foo2(x = "string", b: number) {

function foo3(x: string | undefined = "string", b: number) {
x.length; // ok, should be string
x = undefined;
}

function foo4(x: string | undefined = undefined, b: number) {
x; // should be string | undefined
x = undefined;
}


Expand Down Expand Up @@ -72,10 +74,12 @@ function foo2(x, b) {
function foo3(x, b) {
if (x === void 0) { x = "string"; }
x.length; // ok, should be string
x = undefined;
}
function foo4(x, b) {
if (x === void 0) { x = undefined; }
x; // should be string | undefined
x = undefined;
}
// .d.ts should have `string | undefined` for foo1, foo2, foo3 and foo4
foo1(undefined, 1);
Expand Down
40 changes: 24 additions & 16 deletions tests/baselines/reference/defaultParameterAddsUndefinedWithStrictNullChecks.symbols
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Expand Up @@ -66,16 +66,24 @@ function foo3(x: string | undefined = "string", b: number) {
>x.length : Symbol(String.length, Decl(lib.d.ts, --, --))
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 17, 14))
>length : Symbol(String.length, Decl(lib.d.ts, --, --))

x = undefined;
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 17, 14))
>undefined : Symbol(undefined)
}

function foo4(x: string | undefined = undefined, b: number) {
>foo4 : Symbol(foo4, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 19, 1))
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 21, 14))
>foo4 : Symbol(foo4, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 20, 1))
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 22, 14))
>undefined : Symbol(undefined)
>b : Symbol(b, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 21, 48))
>b : Symbol(b, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 22, 48))

x; // should be string | undefined
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 21, 14))
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 22, 14))

x = undefined;
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 22, 14))
>undefined : Symbol(undefined)
}


Expand All @@ -94,40 +102,40 @@ foo3(undefined, 1);
>undefined : Symbol(undefined)

foo4(undefined, 1);
>foo4 : Symbol(foo4, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 19, 1))
>foo4 : Symbol(foo4, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 20, 1))
>undefined : Symbol(undefined)


function removeUndefinedButNotFalse(x = true) {
>removeUndefinedButNotFalse : Symbol(removeUndefinedButNotFalse, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 31, 19))
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 34, 36))
>removeUndefinedButNotFalse : Symbol(removeUndefinedButNotFalse, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 33, 19))
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 36, 36))

if (x === false) {
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 34, 36))
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 36, 36))

return x;
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 34, 36))
>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 36, 36))
}
}

declare const cond: boolean;
>cond : Symbol(cond, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 40, 13))
>cond : Symbol(cond, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 42, 13))

function removeNothing(y = cond ? true : undefined) {
>removeNothing : Symbol(removeNothing, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 40, 28))
>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 41, 23))
>cond : Symbol(cond, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 40, 13))
>removeNothing : Symbol(removeNothing, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 42, 28))
>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 43, 23))
>cond : Symbol(cond, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 42, 13))
>undefined : Symbol(undefined)

if (y !== undefined) {
>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 41, 23))
>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 43, 23))
>undefined : Symbol(undefined)

if (y === false) {
>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 41, 23))
>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 43, 23))

return y;
>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 41, 23))
>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 43, 23))
}
}
return true;
Expand Down
12 changes: 11 additions & 1 deletion tests/baselines/reference/defaultParameterAddsUndefinedWithStrictNullChecks.types
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Expand Up @@ -86,14 +86,19 @@ function foo2(x = "string", b: number) {

function foo3(x: string | undefined = "string", b: number) {
>foo3 : (x: string | undefined, b: number) => void
>x : string
>x : string | undefined
>"string" : "string"
>b : number

x.length; // ok, should be string
>x.length : number
>x : string
>length : number

x = undefined;
>x = undefined : undefined
>x : string | undefined
>undefined : undefined
}

function foo4(x: string | undefined = undefined, b: number) {
Expand All @@ -104,6 +109,11 @@ function foo4(x: string | undefined = undefined, b: number) {

x; // should be string | undefined
>x : string | undefined

x = undefined;
>x = undefined : undefined
>x : string | undefined
>undefined : undefined
}


Expand Down
2 changes: 2 additions & 0 deletions tests/cases/compiler/defaultParameterAddsUndefinedWithStrictNullChecks.ts
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Expand Up @@ -19,10 +19,12 @@ function foo2(x = "string", b: number) {

function foo3(x: string | undefined = "string", b: number) {
x.length; // ok, should be string
x = undefined;
}

function foo4(x: string | undefined = undefined, b: number) {
x; // should be string | undefined
x = undefined;
}


Expand Down