New FAIL on gdb.base/printcmds.exp (was: Re: [RFA] Ensure GDB printf command can print convenience var strings without a target.)

[Sergio Durigan Junior <sergiodj@redhat.com>]

On Monday, July 08 2019, Philippe Waroquiers wrote:

> On Mon, 2019-07-08 at 19:12 +0100, Pedro Alves wrote:
>> Looks fine to me, with the nits below fixed.
> Thanks.  I have applied all the suggested changes (except one)
> and pushed the below patch as a result.
>
> I kept 
>   gdb_test "set language ada" ".*" "set language ada"
> and clarified why with:
> +	# Without a target, the below produces no output
> +	# but with a target, it gives a warning.
> +	# So, use gdb_test expecting ".*" instead of gdb_test_no_output.
> +	gdb_test "set language ada" ".*" "set language ada"

Hi Philippe,

I'm seeing new FAILures on gdb.base/printcmds.exp:

  new FAIL: gdb.base/printcmds.exp: conv var: with target, may-call-functions off: printf $wstr
  new FAIL: gdb.base/printcmds.exp: conv var: with target, may-call-functions off: set $wstr
  new FAIL: gdb.base/printcmds.exp: conv var: with target: printf $wstr
  new FAIL: gdb.base/printcmds.exp: conv var: with target: set $wstr

The BuildBot has caught them:

  https://sourceware.org/ml/gdb-testers/2019-q3/msg00361.html

The problem happens because GDB can't identify the wchar_t type:

  set var $wstr = L"facile"
  No type named wchar_t.
  (gdb) FAIL: gdb.base/printcmds.exp: conv var: with target: set $wstr

The patch below fixes the problem for me.  wchar_t is built-in on C++,
so the trick is to set the language to "c++" before dealing with it (and
restore the language back to "auto" later).  WDYT?

-- 
Sergio
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gdb/testsuite/ChangeLog:
2019-07-09  Sergio Durigan Junior  <sergiodj@redhat.com>

	* gdb.base/printcmds.exp (test_printf_convenience_var): Set
	language to "c++" before dealing with wchar_t.

diff --git a/gdb/testsuite/gdb.base/printcmds.exp b/gdb/testsuite/gdb.base/printcmds.exp
index 0e3126bcf2..aaa4d8d07d 100644
--- a/gdb/testsuite/gdb.base/printcmds.exp
+++ b/gdb/testsuite/gdb.base/printcmds.exp
@@ -959,10 +959,12 @@ proc test_printf_convenience_var {prefix do_wstring} {
 	gdb_test "printf \"astr val = %s\\n\", \$astr" "astr val = fghij" \
 	    "printf \$astr, auto language"
 	if {$do_wstring} {
+	    gdb_test_no_output "set language c++"
 	    gdb_test_no_output "set var \$wstr = L\"facile\"" \
 		"set \$wstr"
 	    gdb_test "printf \"wstr val = %ls\\n\", \$wstr" \
 		"wstr val = facile" "printf \$wstr"
+	    gdb_test_no_output "set language auto"
 	}
     }
 }