The following program compiles with g++ -O3 without errors or warnings but sets crash at the first printf. It seems to zero the stack pointer before calling printf.
----- Begin switch-crash.ii # 1 "switch-crash.cpp" # 1 "<built-in>" # 1 "<command-line>" # 1 "switch-crash.cpp" extern "C" int printf (__const char *__restrict __format, ...); int f(int len) { switch(1) { case 1: char x[len]; break; } printf("Done\n"); } int main() { f(1); printf("Done\n"); } ------ End switch-crash.ii Output of g++ -v: Using built-in specs. Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.4.3-4ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i486 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5) -- Summary: Declaring an array with non-constant length inside a switch corrupts stack pointer. Product: gcc Version: 4.4.3 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: mark dot haines at openmarket dot com GCC target triplet: x86_64-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44613