> To be fair to clang, one big motivating reason for starting clang (one of the reasons I got involved in helping clang myself) was the fact that at that time GCC would refuse any patch which made it easier for anyone to get a C++ parse tree out of gcc.

A friend of mine is a long-time kibitzer of C compilers, and his occasional remarks about the state of the world wholly harmonize with this - GCC was not good for interop, and the contributing process has a higher bar than others.