[Runtime] Fix leak in tryDynamicCastBoxedSwiftValue.

mikeash · mikeash · commit 58ab8f88367e · 2018-11-30T15:43:29.000-05:00
The call to swift_unboxFromSwiftValueWithType needs to destroy the value on success when requested in the flags.

rdar://problem/44686587
diff --git a/stdlib/public/runtime/Casting.cpp b/stdlib/public/runtime/Casting.cpp
@@ -1922,6 +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

Original file line number	Diff line number	Diff line change
`@@ -1922,6 +1922,9 @@ static bool tryDynamicCastBoxedSwiftValue(OpaqueValue *dest,`
`1922`	`1922`
`1923`	`1923`	`#if !SWIFT_OBJC_INTEROP // __SwiftValue is a native class:`
`1924`	`1924`	`if (swift_unboxFromSwiftValueWithType(src, dest, targetType)) {`
	`1925`	`+ // Release the source if we need to.`
	`1926`	`+ if (flags & DynamicCastFlags::TakeOnSuccess)`
	`1927`	`+ srcType->vw_destroy(src);`
`1925`	`1928`	`return true;`
`1926`	`1929`	`}`
`1927`	`1930`	`#endif`