Annex C (informative) Compatibility [diff]

C.4 C++ and ISO C++ 2003 [diff.cpp03]

C.4.14 [input.output]: input/output library [diff.cpp03.input.output]

Affected subclauses: [istream.sentry], [ostream.sentry], and [iostate.flags]

Change: Specify use of explicit in existing boolean conversion functions.

Rationale: Clarify intentions, avoid workarounds.

Effect on original feature: Valid C++ 2003 code that relies on implicit boolean conversions will fail to compile with this International Standard.

Such conversions occur in the following conditions:

(1.1)
passing a value to a function that takes an argument of type bool;
(1.2)
using operator== to compare to false or true;
(1.3)
returning a value from a function with a return type of bool;
(1.4)
initializing members of type bool via aggregate initialization;
(1.5)
initializing a const bool& which would bind to a temporary object.

Affected subclause: [ios.failure]

Change: Change base class of std::ios_base::failure.

Rationale: More detailed error messages.

Effect on original feature: std::ios_base::failure is no longer derived directly from std::exception, but is now derived from std::system_error, which in turn is derived from std::runtime_error.

Valid C++ 2003 code that assumes that std::ios_base::failure is derived directly from std::exception may execute differently in this International Standard.

Affected subclause: [ios.base]

Change: Flag types in std::ios_base are now bitmasks with values defined as constexpr static members.

Rationale: Required for new features.

Effect on original feature: Valid C++ 2003 code that relies on std::ios_base flag types being represented as std::bitset or as an integer type may fail to compile with this International Standard.

For example:

#include <iostream>

int main() {
  int flag = std::ios_base::hex;
  std::cout.setf(flag);         // error: setf does not take argument of type int
}