Automatic array allocation upon assignment in Fortran

Question

We recently discovered we were making an assignment to an unallocated array in Fortran. The GNU gfortran compiler didn\'t catch the error, and the code runs under both OSX

Answer 1

It turns out that only GNU gfortran 4.6 and above allow for automatic reallocation of LHS arrays in F90. Using the compiler flag -fno-realloc-lhs disables this feature and triggers seg. faults in all cases I described above (OSX, Linux, PPC) Mystery solved! Thanks to mystery poster whose comment mysteriously disappeared.

See GCC 4.6 Wiki