[Bug c++/51885] g++ compiler options -O2 and -O3 modifies program results

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51885

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-01-17 18:44:32 UTC ---
The reinterpret_cast definitely results in undefined behaviour, because it
accesses the float objects through a different type, violating [basic.lval]/10

And indeed, -fno-strict-aliasing makes the problem go away.

Someone didn't read http://gcc.gnu.org/bugs/ carefully.