[PATCH 1/2] Use common_val_print_checked in print_variable_and_value

[Tom Tromey <tromey@adacore.com>]

GDB was crashing in "bt full" for a large Ada program.  I tracked this
down to a combination of bugs.

The first bug, fixed here, is that print_variable_and_value calls
common_val_print.  Normally only the value-printing implementation
should call this; from the top level, common_val_print_checked is
preferred, because it correctly handles values that are wholly
optimized out.

I wasn't able to write a test case for this.

gdb/ChangeLog
2021-04-01  Tom Tromey  <tromey@adacore.com>

	* printcmd.c (print_variable_and_value): Use
	common_val_print_checked.
---
 gdb/ChangeLog  | 5 +++++
 gdb/printcmd.c | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index c82f709136f..a4f62f207d0 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -2387,7 +2387,7 @@ print_variable_and_value (const char *name, struct symbol *var,
       val = read_var_value (var, NULL, frame);
       get_user_print_options (&opts);
       opts.deref_ref = 1;
-      common_val_print (val, stream, indent, &opts, current_language);
+      common_val_print_checked (val, stream, indent, &opts, current_language);
 
       /* common_val_print invalidates FRAME when a pretty printer calls inferior
 	 function.  */
-- 
2.26.2