On Mon, Dec 27, 2010 at 3:37 PM, Michel MORIN
Neil Groves wrote:
You might get a quicker response from the GCC team, but I'm happy to look into this issue if you provide the exact version of GCC and library version you are using. It will, of course, take me a while since I'll have to setup the compiler and environment.
You might want to take a look at the relevant standard library, or the compiler implementation of the new 'for' syntax. I suspect there might be an unqualified call to begin() and/or end().
For this issue, there is some information in the following thread: (a patch and a test case are also provided in the thread.) http://article.gmane.org/gmane.comp.lib.boost.devel/211863
If we are allowed to break existing codes that rely on ADL to find boost::begin/end, this issue can be easily resolved by putting boost::begin/end into an ADL-barrier namespace and bringing them into namespace boost with a using directive.
None of our boost code should be using unqualified calls to begin/end. The Boost.Range design explicitly provided range_begin and range_end as the function names to be found via ADL so that everyone could use qualified boost::begin and boost::end calls. boost::begin and boost::end are explicitly qualified throughout Boost.Range and hence the ambiguous call isn't coming from Boost.Range. Please see http://www.boost.org/doc/libs/1_45_0/libs/range/doc/html/range/reference/ext... the relevant documentation. Hence we can certainly break code that is erroneously relying on ADL for begin/end to be found via ADL. However in this case I have yet to understand the nature of the underlying problem, because there isn't an obvious unqualified call to begin/end. The reverse adaptor uses qualified calls that can't possibly be ambiguous with std::begin/end. I haven't yet checked to see if unqualified calls to begin/end are intended to be used as an extension mechanism for the next C++ standard. I shall put begin and end in an ADL barrier namespace anyhow, since these are explicitly designed to be qualified when called.
Regards, Michel
Regards, Neil Groves