http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51270
Bug #: 51270 Summary: constness violation is accepted without any warning but leads to a required function call being eliminated during optimization Classification: Unclassified Product: gcc Version: 4.6.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassig...@gcc.gnu.org ReportedBy: michiel_dewi...@agilent.com Created attachment 25884 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25884 Standalone source file Bug summary: constness violation is accepted without any warning but leads to a required function call being eliminated during optimization The code itself has a problem in the function "faulty_compiled_function": Feeding the return value of "pass_through" as argument to "recast_reference" violates "const" regulations. This error is never caught by at least g++ 4.4.2 and g++ 4.6.2 on x86_64. Far worse, when compiling with -O1 or bigger, the optimizer eliminates the call to "pass_through" and feeds invalid data into "recast_reference". Proposed treatment: Either there must be an error keeping this code from compiling, or the optimization must be able to handle it properly. Bug triggered as follows: Compile using "g++ -O faulty_optimization_of_invalid_const_usage.cpp" Run "./a.out ; echo $0" This should return exit code 0. It returns exit code 1. Without optimization, there is no error. The error occurs at any nonzero optimization level, even when using -fno-strict-aliasing -fno-inline -fno-omit-stack-frame. $ gcc -v COLLECT_GCC=gcc_x86_64 COLLECT_LTO_WRAPPER=/gfs/belgium/gntnas01/d3/hped_build_gent/tools/gcc/4.6.2/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.6.2/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ./configure --prefix=/hped/builds/tools/gcc/4.6.2 --enable-languages=c,c++ --with-gmp=/hfs/d1/local/dbjornba/btmp --with-mpfr=/hfs/d1/local/dbjornba/btmp --with-mpc=/hfs/d1/local/dbjornba/btmp Thread model: posix gcc version 4.6.2 (GCC)