Submitter:Fred Tydeman
Submission Date: 2018年12月12日
Document: WG14 N2324
Reference Documents: N1942
Summary
SD3 item 13 (DR 482) against C2X: Macro invocation span files.
It was decided that DR 482 would be fixed in C2X as undefined behaviour.
Possible Technical Corrigendum:
Add to §5.1.1.2 (Translation phases), paragraph 1, bullet 3, words along the lines of:
(追記) A macro invocation shall be contained within one source file. (追記ここまで)
Add after §6.10.3 (Macro replacement), paragraph 6 (constraints), a new paragraph:
(追記) A macro invocation shall be contained within one source file. (追記ここまで)
Add after §6.10.3 (Macro replacement), paragraph 12 (semantics), a new paragraph:
(追記) A macro invocation that spans two or more files is undefined behavior. (追記ここまで)
Add to J.2 Undefined behavior
(追記) A macro invocation that spans two or more files is undefined behavior. (追記ここまで)
Existing practice
Some implementations accept (as required by all previous versions of the C standard) a macro invocation that is split between two or more files. Other implementations, consider it a translation error and will not compile such code. Making this undefined allows both sets of implementations to conform. This is a silent change.