We define a specialization of LLSDParam<const char*> to support passing an
LLSD object to a const char* function parameter. Needless to remark, passing
object.asString().c_str() would be Bad: destroying the temporary std::string
returned by asString() would immediately invalidate the pointer returned by
its c_str(). But when you pass LLSDParam<const char*>(object) as the
parameter, that specialization itself stores the std::string so the c_str()
pointer remains valid as long as the LLSDParam object does.
Then there's LLSDParam<LLSD>, used when we don't have the parameter type
available to select the LLSDParam specialization. LLSDParam<LLSD> defines a
templated conversion operator T() that constructs an LLSDParam<T> to provide
the actual parameter value. So far, so good.
The trouble was with the implementation of LLSDParam<LLSD>: it constructed a
_temporary_ LLSDParam<T>, implicitly called its operator T() and immediately
destroyed it. Destroying LLSDParam<const char*> destroyed its stored string,
thus invalidating the c_str() pointer before the target function was entered.
Instead, make LLSDParam<LLSD>::operator T() capture each LLSDParam<T> it
constructs, extending its lifespan to the lifespan of the LLSDParam<LLSD>
instance. For this, derive each LLSDParam specialization from LLSDParamBase, a
trivial base class that simply establishes the virtual destructor. We can then
capture any specialization as a pointer to LLSDParamBase.
Also restore LazyEventAPI tests on Mac.
clang has gotten smart enough to recognize an inline attempt to store to
address zero. Fool it by storing to an address passed as a parameter, and pass
nullptr from a different source file.
Even though LLVersionInfo::getBuild() already returns a 64-bit int, various
consumers assumed it could fit into 32 bits. It was especially bad to pass it
to a classic C style varargs function. Only on a little-endian CPU, and only
because it was the last argument, the damage was limited to truncation --
instead of arbitrary undefined behavior.
Where the consumer doesn't support 64-bit ints, pass as string instead.
Maxim Nikolenko