Improve our handling of user-defined conversions as part of overload
resolution. There are two sources of problems involving user-defined
conversions that this change eliminates, along with providing simpler
interfaces for checking implicit conversions:

  - It eliminates a case of infinite recursion found in Boost.

  - It eliminates the search for the constructor needed to copy a temporary
    generated by an implicit conversion from overload
    resolution. Overload resolution assumes that, if it gets a value
    of the parameter's class type (or a derived class thereof), there
    is a way to copy if... even if there isn't. We now model this
    properly.




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101680 91177308-0d34-0410-b5e6-96231b3b80d8
11 files changed