This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 120c. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2026-08-20
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1648. thread_local vs block extern declarations
Section: 9.2.2 [
] Status: C++14 Submitter: Richard Smith Date: 2013-04-12 [Moved to DR at the September, 2013 meeting.]
According to 9.2.2 [
] paragraph 4,
When thread_local is applied to a variable of block scope the storage-class-specifierstatic is implied if it does not appear explicitly.
This, presumably unintentionally, prohibits a declaration like
void f() { extern thread_local int n; } Proposed resolution (April, 2013):
When thread_local is applied to a variable of block scope the storage-class-specifierstatic is implied if it does not appear explicitlyno other storage-class-specifier appears in the decl-specifier-seq.