tests: fix incorrect object construction

Reported by Ken Moffat.
http://lists.gnu.org/archive/html/bug-bison/2013-10/msg00009.html

* tests/c++.at (Exception safety): Here.

NEWS

@@ -4,7 +4,9 @@ GNU Bison NEWS
 
 ** Bug fixes
 
-*** Portability issues in the test suite.
+*** Errors in caret diagnostics
+
+  On some platforms, some errors could result in endless diagnostics.
 
 *** Fixes of the -Werror option
 
@@ -20,6 +22,10 @@ GNU Bison NEWS
   As demonstrated in the documentation, one can now leave spaces between
   "%?" and its "{".
 
+*** Fixes in the test suite
+
+  Bugs and portability issues.
+
 * Noteworthy changes in release 3.0 (2013-07-25) [stable]
 
 ** WARNING: Future backward-incompatibilities!

THANKS

@@ -66,6 +66,7 @@ Johan van Selst           johans@stack.nl
 Jonathan Fabrizio         jonathan.fabrizio@lrde.epita.fr
 Jonathan Nieder           jrnieder@gmail.com
 Juan Manuel Guerrero      juan.guerrero@gmx.de
+Ken Moffat                zarniwhoop@ntlworld.com
 Kees Zeelenberg           kzlg@users.sourceforge.net
 Keith Browne              kbrowne@legato.com
 Laurent Mascherpa         laurent.mascherpa@epita.fr
@@ -79,6 +80,7 @@ Martin Mokrejs            mmokrejs@natur.cuni.cz
 Martin Nylin              martin.nylin@linuxmail.org
 Matt Kraai                kraai@alumni.cmu.edu
 Matt Rosing               rosing@peakfive.com
+Michael Felt              mamfelt@gmail.com
 Michael Hayes             m.hayes@elec.canterbury.ac.nz
 Michael Raskin            7c6f434c@mail.ru
 Michiel De Wilde          mdewilde.agilent@gmail.com

tests/c++.at

@@ -818,7 +818,8 @@ yylex (yy::parser::semantic_type *lvalp)
   case 'l':
     throw std::runtime_error ("yylex");
   default:
-    lvalp]AT_VARIANT_IF([->build (res)], [->obj = new Object (res)])[;
+    lvalp->]AT_VARIANT_IF([build (Object (res))],
+                          [obj = new Object (res)])[;
     // Fall through.
   case 0:
     return res;