[Bug fortran/99043] New: Inconsistent behavior when calling rank(ptr) for assumed-rank null pointer

[gustav.r.jansen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99043

            Bug ID: 99043
           Summary: Inconsistent behavior when calling rank(ptr) for
                    assumed-rank null pointer
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gustav.r.jansen at gmail dot com
  Target Milestone: ---

Created attachment 50156
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50156&action=edit
Source code that reproduces the described behaviour

Calling rank(ptr) on an assumed-rank null pointer dummy argument returns -1
when the procedure is called with an assumed-rank argument, while it returns
the correct rank when the procedure is called with a non-assumed-rank argument.
The attached file contains a small reproducer to illustrate the behavior.

Here is the output when executed: 
 Lvl1: Expected rank 3, got rank:            3
 Lvl2: Expected rank 3, got rank:           -1

Here is the output of the compiler:
/home/software/gcc/10.2.0/bin/gfortran -v -save-temps -Wall -Wextra
-fno-strict-aliasing -fwrapv -fno-aggressive-loop-optimizations
-fsanitize=undefined -o assumed_rank.x main.f90
Driving: /home/software/gcc/10.2.0/bin/gfortran -v -save-temps -Wall -Wextra
-fno-strict-aliasing -fwrapv -fno-aggressive-loop-optimizations
-fsanitize=undefined -o assumed_rank.x main.f90 -l gfortran -l m -shared-libgcc
Using built-in specs.
COLLECT_GCC=/home/software/gcc/10.2.0/bin/gfortran
COLLECT_LTO_WRAPPER=/home/software/gcc/10.2.0/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-10.2.0/configure --prefix=/home/software/gcc/10.2.0
--disable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 10.2.0 (GCC) 
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fno-strict-aliasing'
'-fwrapv' '-fno-aggressive-loop-optimizations' '-fsanitize=undefined' '-o'
'assumed_rank.x' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /home/software/gcc/10.2.0/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/f951 main.f90
-quiet -dumpbase main.f90 -mtune=generic -march=x86-64 -auxbase main -Wall
-Wextra -version -fno-strict-aliasing -fwrapv
-fno-aggressive-loop-optimizations -fsanitize=undefined
-fintrinsic-modules-path
/home/software/gcc/10.2.0/lib/gcc/x86_64-pc-linux-gnu/10.2.0/finclude -o main.s
GNU Fortran (GCC) version 10.2.0 (x86_64-pc-linux-gnu)
        compiled by GNU C version 10.2.0, GMP version 6.1.0, MPFR version
3.1.4, MPC version 1.0.3, isl version isl-0.18-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU Fortran2008 (GCC) version 10.2.0 (x86_64-pc-linux-gnu)
        compiled by GNU C version 10.2.0, GMP version 6.1.0, MPFR version
3.1.4, MPC version 1.0.3, isl version isl-0.18-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fno-strict-aliasing'
'-fwrapv' '-fno-aggressive-loop-optimizations' '-fsanitize=undefined' '-o'
'assumed_rank.x' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 as -v --64 -o main.o main.s
GNU assembler version 2.30 (x86_64-linux-gnu) using BFD version (GNU Binutils
for Ubuntu) 2.30
Reading specs from /home/software/gcc/10.2.0/lib64/../lib64/libgfortran.spec
rename spec lib to liborig
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fno-strict-aliasing'
'-fwrapv' '-fno-aggressive-loop-optimizations' '-fsanitize=undefined' '-o'
'assumed_rank.x' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
COMPILER_PATH=/home/software/gcc/10.2.0/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/:/home/software/gcc/10.2.0/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/:/home/software/gcc/10.2.0/libexec/gcc/x86_64-pc-linux-gnu/:/home/software/gcc/10.2.0/lib/gcc/x86_64-pc-linux-gnu/10.2.0/:/home/software/gcc/10.2.0/lib/gcc/x86_64-pc-linux-gnu/
LIBRARY_PATH=/home/software/gcc/10.2.0/lib64/../lib64/:/home/software/gcc/10.2.0/lib/gcc/x86_64-pc-linux-gnu/10.2.0/:/home/software/gcc/10.2.0/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../lib64/:/lib/x86_64-linux-gnu/:/lib/../lib64/:/usr/lib/x86_64-linux-gnu/:/home/software/gcc/10.2.0/lib64/:/home/software/gcc/10.2.0/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fno-strict-aliasing'
'-fwrapv' '-fno-aggressive-loop-optimizations' '-fsanitize=undefined' '-o'
'assumed_rank.x' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /home/software/gcc/10.2.0/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/collect2
-plugin
/home/software/gcc/10.2.0/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/liblto_plugin.so
-plugin-opt=/home/software/gcc/10.2.0/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/lto-wrapper
-plugin-opt=-fresolution=main.res -plugin-opt=-pass-through=-lgcc_s
-plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lquadmath
-plugin-opt=-pass-through=-lm -plugin-opt=-pass-through=-lgcc_s
-plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc
-plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc
--eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o
assumed_rank.x /usr/lib/x86_64-linux-gnu/crt1.o
/usr/lib/x86_64-linux-gnu/crti.o
/home/software/gcc/10.2.0/lib/gcc/x86_64-pc-linux-gnu/10.2.0/crtbegin.o
-L/home/software/gcc/10.2.0/lib64/../lib64
-L/home/software/gcc/10.2.0/lib/gcc/x86_64-pc-linux-gnu/10.2.0
-L/home/software/gcc/10.2.0/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../lib64
-L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu
-L/home/software/gcc/10.2.0/lib64
-L/home/software/gcc/10.2.0/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../.. main.o
-lgfortran -lm -lubsan -lgcc_s -lgcc -lquadmath -lm -lgcc_s -lgcc -lc -lgcc_s
-lgcc /home/software/gcc/10.2.0/lib/gcc/x86_64-pc-linux-gnu/10.2.0/crtend.o
/usr/lib/x86_64-linux-gnu/crtn.o
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fno-strict-aliasing'
'-fwrapv' '-fno-aggressive-loop-optimizations' '-fsanitize=undefined' '-o'
'assumed_rank.x' '-shared-libgcc' '-mtune=generic' '-march=x86-64'