Contextually type IIFE params by their arguments #8483
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| @@ -8540,6 +8551,13 @@ namespace ts { | |||
| return undefined; | |||
| } | |||
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| function isIife(func: FunctionExpression | MethodDeclaration) { | |||
| return (func.kind === SyntaxKind.FunctionExpression || func.kind === SyntaxKind.ArrowFunction) && | |||
| func.parent.kind === SyntaxKind.ParenthesizedExpression && | |||
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not necessarily. this is a valid iife (function f() {)} ()).
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I suggest using the skipParenthesizedNodes function before checking for a call expression at the top.
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Done, although skipParenthesizedNodes actually goes down, not up (expression = expression.expression), so I just wrote an inline loop to go up (parent = parent.parent)
And address bug with contextually typed arguments that the PR changes exposed.
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@ahejlsberg once I fixed the parenthesis walker, I had trouble with contextually typed lambdas, eg The compile passes and fails correctly, but the .types files stringifies |
| const indexOfParameter = indexOf(func.parameters, parameter); | ||
| if (iife.arguments && indexOfParameter < iife.arguments.length) { | ||
| if (parameter.dotDotDotToken) { | ||
| return createArrayType(getUnionType(map(iife.arguments.slice(indexOfParameter), getTypeOfExpression))); |
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do you really need the array allocation here.
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Switched to a for loop. As we discussed in person, it would be nice to have a map over a range for general use.
Also allocate once instead of twice.
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Lgtm |
Fixes #4142.
Right now rest parameters look at the first matching argument to get their contextual type. This might be wrong.