When compiling the code (taken and simplified from FoX, the FORTRAN XML library):
module charset implicit none private character(len=1), parameter :: SPACE = achar(32) character(len=1), parameter :: NEWLINE = achar(10) character(len=1), parameter :: CARRIAGE_RETURN = achar(13) character(len=1), parameter :: TAB = achar(9) ! ** taking the last one or two items out of the concatenation allows compilation character(len=*), parameter :: whitespace = SPACE//NEWLINE//CARRIAGE_RETURN//TAB public :: whitespace public :: allowed_encoding contains function allowed_encoding(encoding) result(p) character(len=*), intent(in) :: encoding logical :: p character(len=100) :: enc logical :: utf8, usascii, iso88591 ! ** restoring the next line allows compilation ! utf8 = .false. p = utf8.or.usascii.or.iso88591 stop end function allowed_encoding end module charset with the command: gfortran -v -save-temps -c testbug.f90 I get an Internal Error: Using built-in specs. Target: i386-apple-darwin9.2.0 Configured with: ../gcc-4.4-20080509/configure --enable-languages=fortran Thread model: posix gcc version 4.4.0 20080509 (experimental) (GCC) COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.5.3' '-v' '-save-temps' '-c' '-mtune=generic' /usr/local/libexec/gcc/i386-apple-darwin9.2.0/4.4.0/f951 testbug.f90 -fPIC -quiet -dumpbase testbug.f90 -mmacosx-version-min=10.5.3 -mtune=generic -auxbase testbug -version -fintrinsic-modules-path /usr/local/lib/gcc/i386-apple-darwin9.2.0/4.4.0/finclude -o testbug.s GNU Fortran (GCC) version 4.4.0 20080509 (experimental) (i386-apple-darwin9.2.0) compiled by GNU C version 4.4.0 20080509 (experimental), GMP version 4.2.1, MPFR version 2.2.1. GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096 testbug.f90: In function ‘allowed_encoding’: testbug.f90:19: internal compiler error: in gfc_conv_expr, at fortran/trans-expr.c:3589 Please submit a full bug report, with preprocessed source if appropriate. See <http://gcc.gnu.org/bugs.html> for instructions. -- Summary: Internal compiler error: in gfc_conv_expr Product: gcc Version: 4.4.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: j dot wookey at bristol dot ac dot uk GCC build triplet: ../gcc-4.4-20080509/configure --enable- languages=fortran GCC target triplet: i386-apple-darwin9.2.0 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36652