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Type guard intersection types#9031

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ahejlsberg merged 5 commits into
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typeGuardIntersectionTypes
Jun 9, 2016
Merged

Type guard intersection types#9031
ahejlsberg merged 5 commits into
masterfrom
typeGuardIntersectionTypes

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@ahejlsberg
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Fixes #8911.


// All winged beasts with legs
if (hasWings(beast)) {
if (beast.legs === 4) { // ERROR TS2339: Property 'legs' does not exist on type 'Winged'.
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comments are misleading now.

@mhegazy
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mhegazy commented Jun 8, 2016

👍

}
}

// Repro from #9011
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@yortus yortus Jun 9, 2016

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should be #9016

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yortus commented Jun 9, 2016

This is a really great enhancement to type guards.

@ahejlsberg ahejlsberg merged commit 9e12290 into master Jun 9, 2016
@ahejlsberg ahejlsberg deleted the typeGuardIntersectionTypes branch June 9, 2016 05:14
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yortus commented Jun 9, 2016

IMO this is a major improvement to control flow based type inference that should probably be mentioned in the roadmap and in the upcoming 'what's new in TypeScript' for 2.0.

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4 participants