The following are a set of changes to ISO/IEC 9899:1999 (aka C99) that document the exact semantics of the language extension.
5.1.2 Execution environments
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Within either execution environment, a thread is a flow of
control within a program. It is implementation defined whether or not there may be more than one thread associated with a program. It is implementation defined how threads beyond the first are created, the name and type of the function called at thread startup, and how threads may be terminated. However, objects with thread storage duration shall be initialized before thread
6.2.4 Storage durations of objects
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An object whose identifier is declared with the storage-class
__threadhas thread storage duration. Its lifetime is the entire execution of the thread, and its
stored value is initialized only once, prior to thread startup.
6.7.1 Storage-class specifiers
__thread to the list of storage class specifiers in
Change paragraph 2 to
With the exception of
__thread, at most one storage-class
specifier may be given […]. The
__threadspecifier may be used alone, or immediately following
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The declaration of an identifier for a variable that has
block scope that specifies
__threadspecifier shall be used only with variables.