https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82869
Bug ID: 82869
Summary: c_associated does not always give false for null
pointers
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: james.s.spencer at gmail dot com
Target Milestone: ---
I think if a pointer, p, is C_NULL_PTR then c_associated(p) should always
return false. However, I do not see this with gfortran 7.2.0with
-fsanitize=address or when the pointer is initialised when declared.
$ gfortran -v
Using built-in specs.
COLLECT_GCC=gfortran
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/7.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure --prefix=/usr --libdir=/usr/lib
--libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=https://bugs.archlinux.org/
--enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-shared
--enable-threads=posix --enable-libmpx --with-system-zlib --with-isl
--enable-__cxa_atexit --disable-libunwind-exceptions --enable-clocale=gnu
--disable-libstdcxx-pch --disable-libssp --enable-gnu-unique-object
--enable-linker-build-id --enable-lto --enable-plugin
--enable-install-libiberty --with-linker-hash-style=gnu
--enable-gnu-indirect-function --disable-multilib --disable-werror
--enable-checking=release --enable-default-pie --enable-default-ssp
Thread model: posix
gcc version 7.2.0 (GCC)
$ cat test.f90
use, intrinsic :: iso_c_binding
type(c_ptr) :: p
p = c_null_ptr
print *, '(Expect F) ', c_associated(p)
end
$ gfortran test.f90 && ./a.out
(Expect F) F
$ gfortran -fsanitize=address && ./a.out
(Expect F) T
Using -fsanitize=address changes the result. I only see this under (arch)
linux, the
behaviour on my mac laptop running macOS 10.13 with gfortran 7.2.0 is the
expected case in
both invocations.
The behaviour under -fsanitize=address is not consistent though:
$ cat test2.f90
use, intrinsic :: iso_c_binding
type(c_ptr) :: p
p = c_null_ptr
print *, '(Expect F F) ', c_associated(p), c_associated(c_null_ptr)
end
$ gfortran test2.f90 && ./a.out
(Expect F F) F F
$ gfortran -fsanitize=address test2.f90 && ./a.out
(Expect F F) F T
Finally a case which I can reproduce on both linux and macOS 10.13 and doesn't
involve
-fsanitize=address:
$ cat test3.f90
use, intrinsic :: iso_c_binding
type(c_ptr) :: p = c_null_ptr
print *, '(Expect F F) ', c_associated(p), c_associated(c_null_ptr)
end
$ gfortran test3.f90 && ./a.out
(Expect F F) T T
gfortran 6.3.0 (running on a Debian 9 machine) gives the expected result in all
three
cases.
