https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70842
Bug ID: 70842
Summary: internal compiler error with character members within
a polymorphic pointer
Product: gcc
Version: 5.1.0
Status: UNCONFIRMED
Keywords: ice-on-valid-code
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: nathanael.huebbe at informatik dot uni-hamburg.de
Target Milestone: ---
There is a problem with character members of derived types when using
polymorphic pointers, which triggers an ICE. It seems as if gfortran looses
track of the length of `character` members when performing a downcast from a
limited polymorphic type. The bug can be reproduced with this little code
snippet:
$ cat mo_compiler_test.f90
module foo
TYPE, ABSTRACT :: t_Intermediate
END TYPE t_Intermediate
type, extends(t_Intermediate) :: t_Foo
character(:), allocatable :: string
end type t_Foo
contains
subroutine bar(me)
class(t_Intermediate), target :: me
select type(me)
type is(t_Foo)
print*, len(me%string)
end select
end subroutine bar
end module foo
$ gfortran -c -o mo_compiler_test.o mo_compiler_test.f90
f951: internal compiler error: in gfc_add_component_ref, at
fortran/class.c:245
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
I have been able to reproduce this bug with gfortran versions 4.9.3, 5.1.0,
5.3.0, up to the current master in the git-svn mirror (commit a80f3f45b016).
The bug is not present in versions up to 4.9.2. A git-bisect on the git-svn
mirror revealed commit 53ec6b3f003a to be the first bad commit.
It is interesting to note that this bug is not triggered when the `select
type()` argument is an unlimited polymorphic pointer, even if that unlimited
polymorphic pointer is just an alias for a limited polymorphic variable. See
the comments in the attached code for details on this.
