https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65585
Bug ID: 65585 Summary: Implicit allocation of unallocated array with an implicit summation Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran Assignee: unassigned at gcc dot gnu.org Reporter: dirteat at gmail dot com Created attachment 35150 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35150&action=edit 10 lines code reproducing the bug Hi there, I did not find any bug report on this, but the small attached code compiled with gcc-gfortran 4.9.2 implicitely allocate an non-allocated array; or segfault, depending on how the implicit assignement is written. Compiled with: gfortran -c noalloc.f90; gfortran noalloc.o -o bug With the assignemnt written as: iamwild = iamfine I get the following output: Are you fine? 1.00000000 2.00000000 3.00000000 4.00000000 5.00000000 6.00000000 7.00000000 8.00000000 9.00000000 10.0000000 With the assignment written as: iamwild(:) = iamfine(:) I get the expected behavior: ./bug Program received signal SIGSEGV: Segmentation fault - invalid memory reference. Backtrace for this error: #0 0x7F8CF04BA597 #1 0x7F8CF04BABAE #2 0x7F8CEF9C66AF #3 0x400BC3 in MAIN__ at noalloc.f90:? Segmentation fault PS: took me the day to understand why my code was not working with another compiler... :-/