We are seeing a problem with passing ref parameters to
properties. This bug only occurs in certain situations. Consider
the following code:
====
void runTest()
{
Thing t;
t.vPosition = (Clock.currStdTime % 2 == 0) ? Vec(2, 2) : Vec(3,
3);
Vec v = t.vPosition;
outputDebug("%d %d\n", v.x, v.y);
}
struct Vec
{
int x;
int y;
}
struct Thing
{
@property Vec vPosition() { return mPosition; }
@property Vec vPosition( const ref Vec value ) { return
mPosition = value; }
private:
Vec mPosition;
}
===
Now, this code should output either "2 2" or "3 3" depending on
the time. However, on release builds this code will output "0 0"
every time it is run. This seems to happen regardless of the
optimization level (we have tried with -O1 and -O3). Some things
to note is that the bug will NOT occur if any of the following is
true:
- We compile the code in debug mode. - We specify a constant
known at compile time (eg. "true") instead of the
non-deterministic time value. - We save the vector into a
temporary local variable before passing it to the property. - We
remove the "const ref" from the property setter and pass the
vector by value.
Debugging the code reveals that the value passed to the getter is
indeed 0,0, which rules out the getter as the error source.
We are building this on x64 Windows using gdc version 4.6.1
20110627 (gdc hg r826:396ce79e6402(default), using dmd )
(tdm64-1).
Any idea what's going on?
