This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115d. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-10-26
The interaction between linkage specifications (9.11 [dcl.link]) and named or global module purview and attachment (10.1 [module.unit]) is confusing. The addition of linkage declarations attaching their contents to the global module is not fully integrated into the wording and examples would also help.
Suggested resolution:
Change 6.9.3.1 [basic.start.main] paragraph 1 as follows:
A program shall contain exactly one function called main that belongs to the global scope and is attached to the global module. Executing a program starts a main thread of execution (6.9.2 [intro.multithread], 33.4 [thread.threads]) in which the main function is invoked. It is implementation-defined whether a program in a freestanding environment is required to define a main function.
Change 10.1 [module.unit] bullet 7.2 as follows:
- ...
- Otherwise, if the declaration
it is attached to the global module.
is a replaceable global allocation or deallocation function (17.6.3.2 [new.delete.single], 17.6.3.3 [new.delete.array]), or- is a namespace-definition with external linkage
,or- appears within a linkage-specification,
- Otherwise, ...
[ Example:
// Translation unit #1 export module Foo; void f(); // module linkage, attached to named module Foo extern "C++" { export void g(); // nameable by importers void h(); // nameable in Foo's purview }Both g and h have external linkage, are attached to the global module, and can thus also be redeclared in other translation units:
// Legacy header "foo.h" extern "C++" void g(); // Legacy header "foo-internal.h" extern "C++" void h();-- end example ]
A module-declaration that contains neither...
A redeclaration of an entity X is implicitly exported if X was introduced by an exported declaration; otherwise it shall not be exported unless it has external linkage..