This has just bit me, so i though it would be nice to avoid that next time :)
Basically, it's likely to happen if you don't like shadowing issues,
and use -Wshadow and friends. And it won't be diagnosed by clang.
The reason is, these self-assign diagnostics only work for builtin assignment
operators. Which makes sense, one could have a very special operator=,
that does something unusual in case of self-assignment,
so it may make sense to not warn on that.
But while it may be intentional in some cases, it may be a bug in other cases,
so it would be really great to have some diagnostic about it...