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This commit is contained in:
Jason Freeman
2015-03-16 14:52:03 -07:00
parent bd811cea2a
commit 90fae03f1f
1 changed files with 21 additions and 3 deletions
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src/compiler/checker.ts
+21 -3
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@@ -4615,10 +4615,18 @@ module ts {
if (target === typeParameters[i]) {
let inferences = context.inferences[i];
if (!inferences.isFixed) {
// Any inferences that are made to a type parameter in a union type are inferior
// to inferences made to a flat (non-union) type. This is because if we infer to
// T | string[], we really don't know if we should be inferring to T or not (because
// the correct constituent on the target side could be string[]). Therefore, we put
// such inferior inferences into a secondary bucket, and only use them if the primary
// bucket is empty.
let candidates = inferiority ?
inferences.secondary || (inferences.secondary = []) :
inferences.primary || (inferences.primary = []);
if (!contains(candidates, source)) candidates.push(source);
if (!contains(candidates, source)) {
candidates.push(source);
}
}
return;
}
@@ -6358,12 +6366,22 @@ module ts {
// Clear out all the inference results from the last time inferTypeArguments was called on this context
for (let i = 0; i < typeParameters.length; i++) {
// As an optimization, we don't have to clear (and later recompute) inferred types
// for type parameters that have already been fixed on the previous call to inferTypeArguments
// for type parameters that have already been fixed on the previous call to inferTypeArguments.
// It would be just as correct to reset all of them. But then we'd be repeating the same work
// for the type parameters that were fixed, namely the work done by getInferredType.
if (!context.inferences[i].isFixed) {
context.inferredTypes[i] = undefined;
}
}
if (context.failedTypeParameterIndex >= 0 && !context.inferences[context.failedTypeParameterIndex].isFixed) {
// On this call to inferTypeArguments, we may get more inferences for certain type parameters that were not
// fixed last time. This means that a type parameter that failed inference last time may succeed this time,
// or vice versa. Therefore, the failedTypeParameterIndex is useless if it points to an unfixed type parameter,
// because it may change. So here we reset it. However, getInferredType will not revisit any type parameters
// that were previously fixed. So if a fixed type parameter failed previously, it will fail again because
// it will contain the exact same set of inferences. So if we reset the index from a fixed type parameter,
// we will lose information that we won't recover this time around.
if (context.failedTypeParameterIndex !== undefined && !context.inferences[context.failedTypeParameterIndex].isFixed) {
context.failedTypeParameterIndex = undefined;
}