------- Comment #3 from gryan at akoostix dot com 2008-03-06 16:38 ------- I understand your concern here, which is why I wrote that I thought that it was "implicit".
The standard says "where get<i>(t) == get<i>(u)" is a valid expression" only, however; 6.1.3.4 says that get<i>(t) is "ill formed if I is out of bounds." In the original proposal Jarvi writes "An attempt to compare two tuples of different lengths results in a compile time error." This is co-operated by Becker in his TR-1 book, where we writes "... can be compared if they have the same number of elements..." But the standard itself isn't so explicit. To me, if get<i>(t) fails to compile under the assumption of "ill formed", then by the definitions of 6.1.3.5, get<i>(t) == get<i>(u) should also fail to compile. Although it is not explicitly stated in N1836=05-0096. At least that's my interpretation of "ill-formed." Are all ill-formed expression compilation errors? On an aside, it would certainly be useless to have something compile and run with no side effects (as it does) when the construct is clearly erroneous. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35480
