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[Runtime] Fix leak when casting to AnyHashable. #20836

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Merged
merged 2 commits into from
Nov 30, 2018
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[Runtime] Fix leak when casting to AnyHashable. #20836

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331f0d2
[Runtime] Fix leak when casting to AnyHashable.
mikeash Nov 28, 2018
f1f8396
[Runtime] Fix leak in tryDynamicCastBoxedSwiftValue.
mikeash Nov 29, 2018
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19 changes: 6 additions & 13 deletions stdlib/public/runtime/Casting.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -635,23 +635,13 @@ static bool _dynamicCastToAnyHashable(OpaqueValue *destination,

// If we do find one, the cast succeeds.

// The intrinsic wants the value at +1, so we have to copy it into
// a temporary.
ValueBuffer buffer;
bool mustDeallocBuffer = false;
if (!(flags & DynamicCastFlags::TakeOnSuccess)) {
auto *valueAddr = sourceType->allocateBufferIn(&buffer);
source = sourceType->vw_initializeWithCopy(valueAddr, source);
mustDeallocBuffer = true;
}

// Initialize the destination.
_swift_convertToAnyHashableIndirect(source, destination,
sourceType, hashableConformance);

// Deallocate the buffer if we used it.
if (mustDeallocBuffer) {
sourceType->deallocateBufferIn(&buffer);
// Destroy the value if requested.
if (flags & DynamicCastFlags::TakeOnSuccess) {
sourceType->vw_destroy(source);
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@rjmccall rjmccall Nov 29, 2018 •
edited
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The other way of doing this, by the way, would be to mark the intrinsic parameter as __owned. I don't have an opinion about whether TakeOnSuccess or !TakeOnSuccess is more important to optimize.

}

// The cast succeeded.
Expand Down Expand Up @@ -1932,6 +1922,9 @@ static bool tryDynamicCastBoxedSwiftValue(OpaqueValue *dest,

#if !SWIFT_OBJC_INTEROP // __SwiftValue is a native class:
if (swift_unboxFromSwiftValueWithType(src, dest, targetType)) {
// Release the source if we need to.
if (flags & DynamicCastFlags::TakeOnSuccess)
srcType->vw_destroy(src);
return true;
}
#endif
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10 changes: 10 additions & 0 deletions test/stdlib/AnyHashableCasts.swift.gyb
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Expand Up @@ -118,6 +118,16 @@ AnyHashableCasts.test("${valueExpr} as ${coercedType} as? ${castType}") {
}
% end

AnyHashableCasts.test("Casting to AnyHashable doesn't leak") {
do {
let tracked = LifetimeTracked(42)
let anyHashable = AnyHashable(tracked)
let anyObject = anyHashable as AnyObject
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This is testing two different cases. Aren't there 3 types of cast consumption? I think you will need a full on address only type to test that, no? Maybe my memory is wrong.

_ = anyObject as? AnyHashable
}
expectEqual(LifetimeTracked.instances, 0)
}

#if _runtime(_ObjC)
// A wrapper type around Int that bridges to NSNumber.
struct IntWrapper1: _SwiftNewtypeWrapper, Hashable, _ObjectiveCBridgeable {
Expand Down