http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53364
Bug #: 53364 Summary: [4.7/4.8 Regression] Wrong code generation Classification: Unclassified Product: gcc Version: 4.7.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassig...@gcc.gnu.org ReportedBy: f...@fuhm.net On the following code, minimized from a much larger program: test.cpp ===================== #include <algorithm> struct A { int m_x; explicit A(int x) : m_x(x) {} operator int() const { return m_x; } }; struct B : public A { public: explicit B(int x) : A(x) {} }; int data = 1; int main() { B b = B(10); b = std::min(b, B(data)); return int(b); } ================= Running: g++ -O2 -c test.cpp With gcc version: g++ (Debian 4.7.0-8) 4.7.0 (which says it's built from r187339 on the gcc 4.7 branch). On architecture: x86-64 The program ought to return 1, but instead, it returns randomness. Running valgrind confirms that this program is using uninitialized values. Testing with the debian gcc-snapshot package (trunk rev 187013) shows the same bug. Testing with the debian gcc 4.6.3 package does not show the bug. Using -O1 does not show the bug. Using -O1 -fstrict-aliasing shows the bug.