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Remove undefined from initialized+annotated parameter type

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This commit is contained in:
Nathan Shively-Sanders 2017-01-30 14:59:23 -08:00
parent bb40819f75
commit a235d544f3
1 changed files with 12 additions and 1 deletions
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13
src/compiler/checker.ts
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@ -3286,6 +3286,16 @@ 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) {
@ -3319,7 +3329,8 @@ namespace ts {
// Use type from type annotation if one is present
if (declaration.type) {
return addOptionality(getTypeFromTypeNode(declaration.type), /*optional*/ declaration.questionToken && includeOptionality);
const declaredType = removeOptionalityFromAnnotation(getTypeFromTypeNode(declaration.type), declaration);
return addOptionality(declaredType, /*optional*/ declaration.questionToken && includeOptionality);
}
if ((compilerOptions.noImplicitAny || declaration.flags & NodeFlags.JavaScriptFile) &&