Gcc/10.2.0/gcc/C 002b 002b98-Thread 002dLocal-Edits
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6.64.2 ISO/IEC 14882:1998 Edits for Thread-Local Storage
The following are a set of changes to ISO/IEC 14882:1998 (aka C++98) that document the exact semantics of the language extension.
[intro.execution]
New text after paragraph 4
A thread is a flow of control within the abstract machine.
It is implementation defined whether or not there may be more than
one thread.
New text after paragraph 7
It is unspecified whether additional action must be taken to ensure when and whether side effects are visible to other threads.
[lex.key]
Add
__thread
.[basic.start.main]
Add after paragraph 5
The thread that begins execution at the
main
function is calledthe main thread. It is implementation defined how functions beginning threads other than the main thread are designated or typed. A function so designated, as well as the
main
function, is called a thread startup function. It is implementation defined what happens if a thread startup function returns. It is implementationdefined what happens to other threads when any thread calls
exit
.[basic.start.init]
Add after paragraph 4
The storage for an object of thread storage duration shall be
statically initialized before the first statement of the thread startup function. An object of thread storage duration shall not require
dynamic initialization.
[basic.start.term]
Add after paragraph 3
The type of an object with thread storage duration shall not have a
non-trivial destructor, nor shall it be an array type whose elements
(directly or indirectly) have non-trivial destructors.
[basic.stc]
Add “thread storage duration” to the list in paragraph 1.
Change paragraph 2
Thread, static, and automatic storage durations are associated with objects introduced by declarations […].
Add
__thread
to the list of specifiers in paragraph 3.[basic.stc.thread]
New section before [basic.stc.static]
The keyword
__thread
applied to a non-local object gives the object thread storage duration.A local variable or class data member declared both
static
and__thread
gives the variable or member thread storage duration.[basic.stc.static]
Change paragraph 1
All objects that have neither thread storage duration, dynamic storage duration nor are local […].
[dcl.stc]
Add
__thread
to the list in paragraph 1.Change paragraph 1
With the exception of
__thread
, at most onestorage-class-specifier
shall appear in a givendecl-specifier-seq
. The__thread
specifier may be used alone, or immediately following theextern
orstatic
specifiers. […]Add after paragraph 5
The
__thread
specifier can be applied only to the names of objects and to anonymous unions.[class.mem]
Add after paragraph 6
Non-
static
members shall not be__thread
.
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