Change extension language pretty-printers to use value API

This changes the extension language pretty-printers to use the value
API.

Note that new functions were needed, for both Guile and Python.
Currently both languages always wrap values by removing the values
from the value chain.  This makes sense to avoid strange behavior with
watchpoints, and to avoid excessive memory use.  However, when
printing, it's important to leave the passed-in value untouched, in
case pretty-printing does nothing -- that way the caller can still
access it.

gdb/ChangeLog
2020-03-13  Tom Tromey  <tom@tromey.com>

	* valprint.c (do_val_print): Update.
	* python/python-internal.h (gdbpy_apply_val_pretty_printer): Take
	a struct value.
	(value_to_value_object_no_release): Declare.
	* python/py-value.c (value_to_value_object_no_release): New
	function.
	* python/py-prettyprint.c (gdbpy_apply_val_pretty_printer): Take a
	struct value.
	* guile/scm-value.c (vlscm_scm_from_value_no_release): New
	function.
	* guile/scm-pretty-print.c (gdbscm_apply_val_pretty_printer): Take
	a struct value.
	* guile/guile-internal.h (vlscm_scm_from_value_no_release):
	Declare.
	(gdbscm_apply_val_pretty_printer): Take a struct value.
	* extension.h (apply_ext_lang_val_pretty_printer): Take a struct
	value.
	* extension.c (apply_ext_lang_val_pretty_printer): Take a struct
	value.
	* extension-priv.h (struct extension_language_ops)
	<apply_val_pretty_printer>: Take a struct value.
	* cp-valprint.c (cp_print_value): Create a struct value.
	(cp_print_value): Update.

1 files changed, 15 insertions, 13 deletions

diff --git a/gdb/cp-valprint.c b/gdb/cp-valprint.c
index 77725b7..5e4cb3c 100644
--- a/gdb/cp-valprint.c
+++ b/gdb/cp-valprint.c
@@ -848,13 +848,15 @@ cp_print_value (struct type *type, struct type *real_type,
 	      /* Attempt to run an extension language pretty-printer on the
 		 baseclass if possible.  */
 	      if (!options->raw)
-		result
-		  = apply_ext_lang_val_pretty_printer (baseclass,
-						       thisoffset + boffset,
-						       value_address (base_val),
-						       stream, recurse,
-						       base_val, options,
-						       current_language);
+		{
+		  struct value *v
+		    = value_from_component (base_val, baseclass,
+					    thisoffset + boffset);
+		  result
+		    = apply_ext_lang_val_pretty_printer (v, stream, recurse,
+							 options,
+							 current_language);
+		}
 
 	      if (!result)
 		cp_print_value_fields (baseclass, thistype,
@@ -1006,19 +1008,19 @@ cp_print_value (struct value *val, struct ui_file *stream,
 	    }
 	  else
 	    {
+	      struct value *baseclass_val = value_primitive_field (val, 0,
+								   i, type);
+
 	      /* Attempt to run an extension language pretty-printer on the
 		 baseclass if possible.  */
 	      if (!options->raw)
 		result
-		  = apply_ext_lang_val_pretty_printer (baseclass, boffset,
-						       value_address (base_val),
-						       stream, recurse,
-						       base_val, options,
+		  = apply_ext_lang_val_pretty_printer (baseclass_val, stream,
+						       recurse, options,
 						       current_language);
 
 	      if (!result)
-		cp_print_value_fields (value_primitive_field (val, 0, i, type),
-				       stream, recurse, options,
+		cp_print_value_fields (baseclass_val, stream, recurse, options,
 				       ((struct type **)
 					obstack_base (&dont_print_vb_obstack)),
 				       0);