The following command line causes the gcc/g++ driver front-end to crash with a core dump (segmentation fault):
gcc -O -O -O -O -O -O -O -O -O -O -O -O -O -O -O -O -O -O -O -O -Wall -Wall hello.cpp Note: The example is only meant as easy to reproduce failing case. Actually the problem occured in a command line with mixed options that happened to repeat -Wall two times and by accident had the "right" number of other options -D, -I, ... in a qmake-generated Makefile. The EXACT number of command line options is critical: with more or with lesser options the problem is NOT triggered. Also the option -Wall may be mixed with the others, as long as it appears exactly two times OR three times. For further info complete -v output: Configured with: /gnu/gcc/releases/respins/4.3.4-3a/gcc4-4.3.4-3/src/gcc-4.3.4/configure --srcdir=/gnu/gcc/releases/respins/4.3.4-3a/gcc4-4. 3.4-3/src/gcc-4.3.4 --prefix=/usr --exec-prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin --libexecdir=/usr/lib --datadir=/usr/share --loca lstatedir=/var --sysconfdir=/etc --infodir=/usr/share/info --mandir=/usr/share/man --datadir=/usr/share --infodir=/usr/share/info --mandir=/ usr/share/man -v --with-gmp=/usr --with-mpfr=/usr --enable-bootstrap --enable-version-specific-runtime-libs --with-slibdir=/usr/bin --libexe cdir=/usr/lib --enable-static --enable-shared --enable-shared-libgcc --disable-__cxa_atexit --with-gnu-ld --with-gnu-as --with-dwarf2 --disa ble-sjlj-exceptions --enable-languages=ada,c,c++,fortran,java,objc,obj-c++ --disable-symvers --enable-libjava --program-suffix=-4 --enable-l ibgomp --enable-libssp --enable-libada --enable-threads=posix --with-arch=i686 --with-tune=generic --enable-libgcj-sublibs CC=gcc-4 CXX=g++- 4 CC_FOR_TARGET=gcc-4 CXX_FOR_TARGET=g++-4 GNATMAKE_FOR_TARGET=gnatmake GNATBIND_FOR_TARGET=gnatbind --with-ecj-jar=/usr/share/java/ecj.jar Thread model: posix gcc version 4.3.4 20090804 (release) 1 (GCC) -- Summary: Driver core dump (when duplicating -Wall command line option Product: gcc Version: 4.3.4 Status: UNCONFIRMED Severity: normal Priority: P3 Component: driver AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: Martin dot Weitzel at t-online dot de GCC build triplet: Configured with: ... (see body) GCC host triplet: gcc version 4.3.4 20090804 (release) 1 (GCC) GCC target triplet: Target: i686-pc-cygwin http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45754