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Fix issue 18995 - Make sure GC calls destructor when using std.array.array

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This commit is contained in:
Steven Schveighoffer 2018-06-15 16:34:59 -04:00
parent 15b682af36
commit 4fe18b9055
1 changed files with 54 additions and 9 deletions
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63
std/array.d
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@ -219,6 +219,34 @@ if (isPointer!Range && isIterable!(PointerTarget!Range) && !isNarrowString!Range
assert(a.length == 5);
}
version(unittest)
private extern(C) void _d_delarray_t(void[] *p, TypeInfo_Struct ti);
@system unittest
{
// Issue 18995
int nAlive = 0;
struct S
{
bool alive;
this(int) { alive = true; ++nAlive; }
this(this) { nAlive += alive; }
~this() { nAlive -= alive; alive = false; }
}
import std.algorithm.iteration : map;
import std.range : iota;
auto arr = iota(3).map!(a => S(a)).array;
assert(nAlive == 3);
// No good way to ensure the GC frees this, just call the lifetime function
// directly. If delete wasn't deprecated, this is what delete would do.
_d_delarray_t(cast(void[]*)&arr, typeid(S));
assert(nAlive == 0);
}
/**
Convert a narrow string to an array type that fully supports random access.
This is handled as a special case and always returns an array of `dchar`
@ -698,6 +726,9 @@ if (isDynamicArray!T && allSatisfy!(isIntegral, I))
}
}
// from rt/lifetime.d
private extern(C) void[] _d_newarrayU(const TypeInfo ti, size_t length) pure nothrow;
private auto arrayAllocImpl(bool minimallyInitialized, T, I...)(I sizes) nothrow
{
static assert(I.length <= nDimensions!T,
@ -737,18 +768,24 @@ private auto arrayAllocImpl(bool minimallyInitialized, T, I...)(I sizes) nothrow
}
else
{
import core.memory : GC;
import core.stdc.string : memset;
import core.checkedint : mulu;
bool overflow;
const nbytes = mulu(size, E.sizeof, overflow);
if (overflow) assert(0);
/+
NOTES:
_d_newarrayU is part of druntime, and creates an uninitialized
block, just like GC.malloc. However, it also sets the appropriate
bits, and sets up the block as an appendable array of type E[],
which will inform the GC how to destroy the items in the block
when it gets collected.
auto ptr = cast(E*) GC.malloc(nbytes, blockAttribute!E);
_d_newarrayU returns a void[], but with the length set according
to E.sizeof.
+/
*(cast(void[]*)&ret) = _d_newarrayU(typeid(E[]), size);
static if (minimallyInitialized && hasIndirections!E)
memset(ptr, 0, nbytes);
ret = ptr[0 .. size];
// _d_newarrayU would have asserted if the multiplication below
// had overflowed, so we don't have to check it again.
memset(ret.ptr, 0, E.sizeof * ret.length);
}
}
else static if (I.length > 1)
@ -796,7 +833,15 @@ private auto arrayAllocImpl(bool minimallyInitialized, T, I...)(I sizes) nothrow
}
~this()
{
assert(p != null);
// note, this assert is invalid -- a struct should always be able
// to run its dtor on the .init value, I'm leaving it here
// commented out because the original test case had it. I'm not
// sure what it's trying to prove.
//
// What happens now that minimallyInitializedArray adds the
// destructor run to the GC, is that this assert would fire in the
// GC, which triggers an invalid memory operation.
//assert(p != null);
}
}
auto a = minimallyInitializedArray!(S[])(1);