C++: Support noexcept operator

The code model failed to parse the noexcept operator which is often
used in noexcept specifiers, e.g.: "void f() noexcept(noexcept(g()));"
Consequently some c++11 headers such as unordered_map, array
and unordered_set could not be parsed and no code completition was
available. I have created the NoExceptOperatorExpressionAST class
which is created whenever a noexcept token is found in an
expression with operator precedence. The noExcept test case
in the cplusplus/cxx11 test now contains a function that
uses the noexcept operator.

Fixed noexcept operator parsing

Added the test requested by Sergey Shambir, which then revealed that
i had not implemeneted the noexpect operator parsing according to the
c++ specification.
As stated here http://cpp0x.centaur.ath.cx/expr.unary.noexcept.html
the noexcept operator is a unary-expression that contains an
expression (and not a constant-expression). This should now be fixed.

Change-Id: Id4a99a43b660bd83e7680274491d99a698b57094
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

src/libs/3rdparty/cplusplus/Parser.cpp

@@ -5238,6 +5238,14 @@ bool Parser::parseUnaryExpression(ExpressionAST *&node)
         return true;
     }
 
+
+    case T_NOEXCEPT: {
+        if (!_languageFeatures.cxx11Enabled)
+            break;
+
+        return parseNoExceptOperatorExpression(node);
+    }
+
     default:
         break;
     } // switch
@@ -5674,6 +5682,19 @@ bool Parser::parseThrowExpression(ExpressionAST *&node)
     return false;
 }
 
+bool Parser::parseNoExceptOperatorExpression(ExpressionAST *&node)
+{
+    DEBUG_THIS_RULE();
+    if (_languageFeatures.cxx11Enabled && LA() == T_NOEXCEPT) {
+        NoExceptOperatorExpressionAST *ast = new (_pool) NoExceptOperatorExpressionAST;
+        ast->noexcept_token = consumeToken();
+        parseExpression(ast->expression);
+        node = ast;
+        return true;
+    }
+    return false;
+}
+
 bool Parser::lookAtObjCSelector() const
 {
     switch (LA()) {