std::condition_variable::wait is now a thread cancellation point

In GCC 11 and earlier, the std::condition_variable::wait function was noexcept, which made it incompatible with thread cancellation. As a result, if a call to pthread_cancel canceled a thread blocked in std::condition_variable::wait, the process would be terminated. In GCC 12 and later, std::condition_variable::wait can be canceled by calls to the pthread_cancel function, which unwinds the stack. If you have code that depends on wait never throwing an exception, review the code and take appropriate action.

Deprecated class templates

Certain class templates have been deprecated in new versions of C++ and produce warning diagnostics in GCC 12 and later.

• The following class templates have been deprecated in C++11 and later:
  • std::unary_function
  • std::binary_function
• The std::iterator class template has been deprecated in C++17 and later.

To prevent the warning diagnostics, you can take one of the following actions:

• When you do not want to make other changes to the code, silence the warning diagnostics by using GCC’s diagnostic pragmas. For example:

  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored “-Wdeprecated-declarations"
  class Functor : public std::unary_function<int, int>
  { /* … */ };
  #pragma GCC diagnostic pop

• When you want your code to be compatible with later versions of C++, replace these class templates in the code with nested typedefs. For example, you can replace a std::unary_function base class with result_type and argument_type typedefs:

  class Functor
  {
    using result_type = int;
    using argument_type = int;
    /* … */
  };