1249. basic_ios default ctor

Section: 30.5.5.2 [basic.ios.cons] Status: C++11 Submitter: Martin Sebor Opened: 2009-10-25 Last modified: 2016-02-10

Priority: Not Prioritized

View all other issues in [basic.ios.cons].

View all issues with C++11 status.

Discussion:

The basic_ios default ctor is required to leave the objects members uninitialized (see below). The paragraph says the object must be initialized by calling basic_ios::init() before it's destroyed but I can't find a requirement that it be initialized before calling any of the class other member functions. Am I not looking in the right place or that an issue?

[ 2009-10-25 Daniel adds: ]

I agree, that your wording makes that clearer, but suggest to write

... calling basic_ios::init() before ...

Doing so, I recommend to adapt that of ios_base(); as well, where we have:

Effects: Each ios_base member has an indeterminate value after construction. These members shall be initialized by calling basic_ios::init. If an ios_base object is destroyed before these initializations have taken place, the behavior is undefined.

[ Post-Rapperswil: ]

Moved to Tentatively Ready after 5 positive votes on c++std-lib.

[ Adopted at 2010-11 Batavia ]

Proposed resolution:

Change 30.5.3.7 [ios.base.cons] p1:

ios_base();

Effects: Each ios_base member has an indeterminate value after construction. These The object's members shall be initialized by calling basic_ios::init before the object's first use or before it is destroyed, whichever comes first; otherwise the behavior is undefined.. If an ios_base object is destroyed before these initializations have taken place, the behavior is undefined.

Change 30.5.5.2 [basic.ios.cons] p2:

basic_ios();

Effects: Constructs an object of class basic_ios (27.5.2.7) leaving its member objects uninitialized. The object shall be initialized by calling its basic_ios::init before its first use or before it is destroyed, whichever comes first; otherwise the behavior is undefined. member function. If it is destroyed before it has been initialized the behavior is undefined.