CWG Issue 1648 (original) (raw)

This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 117a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2025-04-13

1648.thread_local vs block extern declarations

Section: 9.2.2 [dcl.stc]Status: C++14Submitter: Richard SmithDate: 2013-04-12

[Moved to DR at the September, 2013 meeting.]

According to 9.2.2 [dcl.stc] paragraph 4,

When thread_local is applied to a variable of block scope the storage-class-specifier static 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-specifier static is implied if it does not appear explicitly no other_storage-class-specifier_ appears in the_decl-specifier-seq_.