This issue has been automatically converted from the original issue lists and some formatting may not have been preserved.
Authors: Robert Paul Corbett, WG14
Date: 1992-12-10
Reference document: X3J11/92-004
Submitted against: C90
Status: Closed
Converted from: dr.htm, dr_043.html
Subclause 7.1.3 implies that an identifier that begins with an underscore cannot be defined as a macro name in any source file that includes at least one standard header. Footnote 91 emphasizes this restriction. Nonetheless, there are texts on Standard C that imply that such macro definitions are allowed.
The first paragraph of subclause 7.1.3 states that each header optionally declares or defines identifiers which are always reserved either for any use or for use as file scope identifiers. The second bullet item states, “All identifiers that begin with an underscore are always reserved for use as identifiers with file scope in both the ordinary identifier and tag name spaces.” The final sentence states, “If the program declares or defines an identifier with the same name as an identifier reserved in that context (other than as allowed by 7.1.7), the behavior is undefined.” Taken together, these statements imply that an identifier that starts with an underscore cannot be defined as a macro in a source file that includes at least one of the standard headers.
Can an identifier that starts with an underscore be defined as a macro in a source file that includes at least one standard header?
Comment from WG14 on 1997-09-23:
No. See subclause 7.1.3 and Footnote 91.