Re: GDB/Fortran: Support for Assumed Rank Zero.

[Kevin Buettner <kevinb@redhat.com>]

Hi Rupesh,

After reading the comments more closely, I found a few more nits;
see below.  I apologize for missing these on the first pass.

I also have a question about how you're testing with clang / flang.

Kevin

On Thu, 14 Apr 2022 10:30:38 +0000
"Potharla, Rupesh" <Rupesh.Potharla@amd.com> wrote:

> If a variable is passed to function in FORTRAN as an argument the
> variable is treated as an array with rank zero. GDB currently does
> not support the case for assumed rank 0. This patch provides support
> for assumed rank 0 and updates the testcase as well.

Please put two spaces after the period in each sentence.  See:

https://www.gnu.org/prep/standards/standards.html#Comments

> Without patch:
> Breakpoint 1, arank::sub1 (a=<error reading variable:
>   failed to resolve dynamic array rank>) at assumedrank.f90:11
> 11       PRINT *, RANK(a)
> (gdb) p a
> failed to resolve dynamic array rank
> (gdb) p rank(a)
> failed to resolve dynamic array rank
> 
> With patch:
> Breakpoint 1, arank::sub1 (a=0) at assumedrank.f90:11
> 11       PRINT *, RANK(a)
> (gdb) p a
> $1 = 0
> (gdb) p rank(a)
> $2 = 0
> ---
>  gdb/gdbtypes.c                            | 11 +++++++----
>  gdb/gdbtypes.h                            |  1 -
>  gdb/testsuite/gdb.fortran/assumedrank.exp |  7 +++++++
>  gdb/testsuite/gdb.fortran/assumedrank.f90 |  3 +++
>  4 files changed, 17 insertions(+), 5 deletions(-)
> 
> diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
> index 49ecb199b07..21db5aafc88 100644
> --- a/gdb/gdbtypes.c
> +++ b/gdb/gdbtypes.c
> @@ -2398,10 +2398,13 @@ resolve_dynamic_array_or_string (struct type *type,
>  
>        if (rank == 0)
>  	{
> -	  /* The dynamic property list juggling below was from the original
> -	     patch.  I don't understand what this is all about, so I've
> -	     commented it out for now and added the following error.  */
> -	  error (_("failed to resolve dynamic array rank"));
> +	  /* Rank is zero, if a variable is passed as an argument to a
> +	     function. GDB considers the variable as an array so discard
> +	     the array type and return the target type which is of variable. */

Two spaces after after each period (end of sentence) in above comment, too.

> +          type->main_type->target_type->main_type->dyn_prop_list =
> +                                  type->main_type->dyn_prop_list;
> +          type = TYPE_TARGET_TYPE (type);
> +          return type;
>  	}
>        else if (type->code () == TYPE_CODE_STRING && rank != 1)
>  	{
[...]
> diff --git a/gdb/testsuite/gdb.fortran/assumedrank.exp b/gdb/testsuite/gdb.fortran/assumedrank.exp
> index 69cd168125f..49b03e2f87f 100644
> --- a/gdb/testsuite/gdb.fortran/assumedrank.exp
> +++ b/gdb/testsuite/gdb.fortran/assumedrank.exp
> @@ -14,6 +14,7 @@
>  # along with this program.  If not, see <http://www.gnu.org/licenses/> .
>  
>  # Testing GDB's implementation of ASSUMED RANK arrays.
> +#Until the assumed rank zero is fixed in clang, XFAIL this case for clang.

Given that you've already put a comment about this below, I think the
above comment could be deleted.  However, if you prefer to retain it,
then insert a space after the '#'.

>  if {[skip_fortran_tests]} { return -1 }
>  
> @@ -58,6 +59,12 @@ while { $test_count < 500 } {
>  	    }
>  	}
>  
> +	# xfail rank 0 for clang
> +	if {$test_count == 1 && [test_compiler_info {clang-*}]} {
> +	   xfail "clang compiler does not support rank0"
> +           continue
> +	}
> +
>  	if ($found_final_breakpoint) {
>  	    break
>  	}

I'm not convinced that this is the best way to xfail the rank 0 test.
However, after I applied only your testsuite changes, I couldn't figure
out how to test with flang instead of gfortran.  Can you tell me how
this is done?

Kevin