This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 112c. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
[Moved to DR at the May, 2015 meeting.]
There does not appear to be any restriction on giving main() an explicit language linkage, but it should probably be either ill-formed or conditionally-supported.
Proposed resolution (November, 2014):
Change 18.104.22.168 [basic.start.main] paragraph 2 as follows:
An implementation shall not predefine the main function. This function shall not be overloaded.
Itshall have a declared return type of type int, but otherwise its type is implementation-defined. An implementation shall allow both...
Change 22.214.171.124 [basic.start.main] paragraph 3 as follows:
The function main shall not be used within a program. The linkage (6.6 [basic.link]) of main is implementation-defined. A program that defines main as deleted or that declares main to be inline, static, or constexpr is ill-formed. The name main is not otherwise reserved...