Also known as concept checking.
The primary author of the checking code, Jeremy Siek, had already started work on a replacement implementation. The new code has been formally reviewed and accepted into the Boost libraries, and we are pleased to incorporate it into the GNU C++ library.
The new version imposes a much smaller space overhead on the generated object file. The checks are also cleaner and easier to read and understand.
They are off by default for all versions of GCC from 3.0 to 3.4 (the
latest release at the time of writing).
They can be enabled at configure time with
--enable-concept-checks
.
You can enable them on a per-translation-unit basis with
#define _GLIBCXX_CONCEPT_CHECKS
for GCC 3.4 and higher
(or with #define _GLIBCPP_CONCEPT_CHECKS
for versions
3.1, 3.2 and 3.3).
Please note that the upcoming C++ standard has first-class support for template parameter constraints based on concepts in the core language. This will obviate the need for the library-simulated concept checking described above.