On Thu, Jan 17, 2013 at 01:21:41PM +0000, Ben Hutchings wrote: > On Thu, 2013-01-17 at 12:06 +0000, Thorsten Glaser wrote: > > Adam Borowski <kilobyte <at> angband.pl> writes: > > > > > #define DEB_HOST_MULTIARCH "x86_64-linux-gnu" > > > > And then #include "<" DEB_HOST_MULTIARCH "/foo/bar.h" or what? > > Is that even valid C? > > It's not standard, nor is it supported in gcc (coincidentally I had a > completely different reason to try it yesterday).
No, it is both blessed by ISO C, and supported by gcc: 6.10.2.2: } # include <h-char-sequence> new-line 6.10.2.3: } # include "q-char-sequence" new-line 6.10.2.4 says: } A preprocessing directive of the form } # include pp-tokens new-line } (that does not match one of the two previous forms) is permitted. The } preprocessing tokens after include in the directive are processed just as } in normal text. (Each identifier currently defined as a macro name is } replaced by its replacement list of preprocessing tokens.) The directive } resulting after all replacements shall match one of the two previous } forms. [...] > > (#include CONFIG_H works in GCC, but…) As required by the above. > That *is* standard, but limited to a single macro. You can combine them as you wish, there's just one trick: the #include line _directly_ can include at most one of delimiters, or otherwise it will match 6.10.2.2 or 6.10.2.3 (yes, it is an unintuitive quirk). Also, the behaviour of ## is unclear and might be what the following discussion declares to be implementation specific, but fortunately, it's not needed: #define STDIO stdio #define _H .h #define sysinclude(x) < x > #include sysinclude(STDIO _H) -- ᛊᚨᚾᛁᛏᚣ᛫ᛁᛊ᛫ᚠᛟᚱ᛫ᚦᛖ᛫ᚹᛖᚨᚲ -- To UNSUBSCRIBE, email to debian-devel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20130117155940.ga6...@angband.pl
