[RFA/commit] Set default target-wide-charset setting to "UTF-16" for x86_64-windows.

[Joel Brobecker <brobecker@adacore.com>]

GDB on x86_64-windows is having trouble printing wide characters.
For instance, from gdb.base/wchar.exp:

    wchar_t narrow = 97;  /* This is 'a' */

Without this patch, GDB prints narrow as:

    $1 = 97 L'\141'

This is because the default target wide charset is UTF-32, whereas
wchar_t is only 16bits long.

gdb/ChangeLog:

        * amd64-windows-tdep.c (amd64_windows_auto_wide_charset): New
        function.
        (amd64_windows_init_abi): Set auto_wide_charset gdbarch method
        to amd64_windows_auto_wide_charset.

Tested on x86_64-windows, using AdaCore's testsuite.  It seems to be
in line with what's done on x86-windows.

I'll commit in a few days unless there are objections.

---
 gdb/amd64-windows-tdep.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c
index 528fbb6..142e141 100644
--- a/gdb/amd64-windows-tdep.c
+++ b/gdb/amd64-windows-tdep.c
@@ -190,6 +190,14 @@ amd64_windows_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
   return destination;
 }
 
+/* Implement the "auto_wide_charset" gdbarch method.  */
+
+static const char *
+amd64_windows_auto_wide_charset (void)
+{
+  return "UTF-16";
+}
+
 static void
 amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 {
@@ -215,6 +223,8 @@ amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   set_gdbarch_iterate_over_objfiles_in_search_order
     (gdbarch, windows_iterate_over_objfiles_in_search_order);
 
+  set_gdbarch_auto_wide_charset (gdbarch, amd64_windows_auto_wide_charset);
+
   set_solib_ops (gdbarch, &solib_target_so_ops);
 }
 
-- 
1.7.9.5