On Tue, Nov 16, 2010 at 6:46 PM, Dave Steffen <dave.stef...@numerica.us> wrote:
> Hi Folks
>
> I've been tracking down some almost-certainly-false-positives.
> Consider the following code:
>
>
> #include <iostream>
> #include <boost/shared_ptr.hpp>
> #include <boost/make_shared.hpp>
>
>
> using namespace std;
> using boost::make_shared;
>
> struct StateSpace {
> public:
>
> StateSpace(int spaceType) {
> if (spaceType == 4)
> cout << "Some Output" << endl;
> }
> };
>
> class State {
> public:
>
>
> State() : m_rep(make_shared<StateSpace>(0) ) {} // #1
> // State() : m_rep(new StateSpace(0) ) {} // #2
>
>
> boost::shared_ptr<StateSpace> m_rep;
> };
>
>
> int main() {
> State state;
> }
>
>
> Valgrind 3.6 reports this:
>
> ==8198== Memcheck, a memory error detector
> ==8198== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
> ==8198== Using Valgrind-3.6.0.SVN-Debian and LibVEX; rerun with -h for
> copyright info
> ==8198== Command: testState
> ==8198==
> ==8198== Conditional jump or move depends on uninitialised value(s)
> ==8198== at 0x401659: StateSpace::StateSpace(int) (testState.cpp:14)
> ==8198== by 0x401796: boost::shared_ptr<StateSpace>
> boost::make_shared<StateSpace, int, >(int&&, ) (make_shared.hpp:150)
> ==8198== by 0x4016BD: State::State() (testState.cpp:22)
> ==8198== by 0x401317: main (testState.cpp:29)
> ==8198==
> ==8198==
> ==8198== HEAP SUMMARY:
> ==8198== in use at exit: 464 bytes in 5 blocks
> ==8198== total heap usage: 240 allocs, 236 frees, 45,162 bytes allocated
> ==8198==
> ==8198== LEAK SUMMARY:
> ==8198== definitely lost: 0 bytes in 0 blocks
> ==8198== indirectly lost: 0 bytes in 0 blocks
> ==8198== possibly lost: 0 bytes in 0 blocks
> ==8198== still reachable: 464 bytes in 5 blocks
> ==8198== suppressed: 0 bytes in 0 blocks
> ==8198== Reachable blocks (those to which a pointer was found) are not shown.
> ==8198== To see them, rerun with: --leak-check=full --show-reachable=yes
> ==8198==
> ==8198== For counts of detected and suppressed errors, rerun with: -v
> ==8198== Use --track-origins=yes to see where uninitialised values come from
> ==8198== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 5 from 5)
>
>
> Interestingly, commenting out line 1 and replacing it with line 2
> produces no errors.
Can you rerun it with: --track-origins=yes ?
Regards
Gateano Mendola
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