Re: [RFA] print arrays with indexes

[Joel Brobecker <brobecker@adacore.com>]

Hmmmm, I was working on transforming one of our internal testcase
(which uses Ada) for the patch below into a dejagnu testcase. It should
all be smooth since I did the testing manually with the patch below,
but it appears I missed something. I'm seeing some unexpected failures.

> 2005-10-02  Joel Brobecker  <brobecker@adacore.com>
> 
>         * language.h (language_defn): New field la_print_array_index.
>         (LA_PRINT_ARRAY_INDEX): New macro.
>         (default_print_array_index): Add declaration.
>         * language.c (default_print_array_index): new function.
>         (unknown_language): Add value for new field.
>         (auto_language): Likewise.
>         (local_language): Likewise.
>         * ada-lang.c (ada_print_array_index): New function.
>         (ada_language_defn): Add value for new field.
>         * c-lang.c (c_language_defn): Likewise.
>         (cpluc_language_defn): Likewise.
>         (asm_language_defn): Likewise.
>         (minimal_language_defn): Likewise.
>         * f-lang.c (f_language_defn): Likewise.
>         * jv-lang.c (java_language_defn): Likewise.
>         * m2-lang.c (m2_language_defn): Likewise.
>         * objc-lang.c (objc_language_defn): Likewise.
>         * p-lang.c (pascal_language_defn): Likewise.
>         * scm-lang.c (scm_language_defn): Likewise.
>         * valprint.h (print_array_indexes_p): Add declaration.
>         (get_array_low_bound): Add declaration.
>         (maybe_print_array_index): Add declaration.
>         * valprint.c (print_array_indexes): New static variable.
>         (show_print_array_indexes): New function.
>         (print_array_indexes_p): New function.
>         (get_array_low_bound): New function.
>         (maybe_print_array_index): New function.
>         (val_print_array_elements): Print the index of each element if
>         requested by the user.
>         (_initialize_valprint): Add new array-indexes "set/show print" command.
>         * ada-valprint.c (print_optional_low_bound): Replace extracted code
>         by call to ada_get_array_low_bound_and_type(). Stop printing the low
>         bound if indexes will be printed for all elements of the array.
>         (val_print_packed_array_elements): Print the index of each element
>         of the array if necessary.

Issues:

1. I now understand the why of the

   if (TYPE_CODE (index_type) == RANGE_TYPE)
     index_type = TYPE_TARGET_TYPE (index_type)

   But this is an Ada-specific thing, and I'll take care of this in
   a separate patch. And I'll add a testcase as a bonus.

2. More annoying, I just tried something else, which is to print an
   empty Ada array. Ada allows you to create this by using declarations
   such as this:

        Table : array (1 .. 0) of Integer;

   Basically, if the lower/left bound is greater than the right/higher
   bound, then the array is empty.

   I just discovered that ada_val_print_1 calls val_print_array_elements
   even if the array is empty.  This triggers one of the guards in
   get_array_low_bound(), since the function expects a non-empty array.

   I'm happy to just put a check in the Ada part to avoid calling
   val_print_array_elements for empty arrays. This should be fine, but
   I'm wondering if other languages might be doing the same, in which
   case it's probably going to be safer to modify a bit
   val_print_array_elements to handle empty arrays...

Sorry about that...

-- 
Joel