Proposed resolution:

For the following functions in [support.start.term].

extern "C" int at_quick_exit(void (*f)(void));
extern "C++" int at_quick_exit(void (*f)(void));

Edit paragraph 10 as follows. The intent is to provide the other half of the happens before relation; to note indeterminate ordering; and to clean up some formatting.

Effects: The at_quick_exit() functions register the function pointed to by f to be called without arguments when quick_exit is called. It is unspecified whether a call to at_quick_exit() that does not happen-before happen before (1.10) all calls to quick_exit will succeed. [Note: the at_quick_exit() functions shall not introduce a data race (17.6.4.7). exitnote —end note] [Note: The order of registration may be indeterminate if at_quick_exit was called from more than one thread. —end note] [Note: The at_quick_exit registrations are distinct from the atexit registrations, and applications may need to call both registration functions with the same argument. —end note]

For the following function.

void quick_exit [[noreturn]] (int status)

Edit paragraph 13 as follows. The intent is to note that thread-local variables may be different.

Effects: Functions registered by calls to at_quick_exit are called in the reverse order of their registration, except that a function shall be called after any previously registered functions that had already been called at the time it was registered. Objects shall not be destroyed as a result of calling quick_exit. If control leaves a registered function called by quick_exit because the function does not provide a handler for a thrown exception, terminate() shall be called. [Note: Functions registered by one thread may be called by any thread, and hence should not rely on the identity of thread-storage-duration objects. —end note] After calling registered functions, quick_exit shall call _Exit(status). [Note: The standard file buffers are not flushed. See: ISO C 7.20.4.4. —end note]

[ 2009 Santa Cruz: ]

The "thread safe" language has already been change in the WP. It was changed to "happen before", but the current WP text is still a little incomplete: "happen before" is binary, but the current WP text only mentions one thing.

Move to Ready.

Addresses UK 187

The term "thread safe" is not defined nor used in this context anywhere else in the standard.

Suggested action:

Clarify the meaning of "thread safe".