Renato Golin of Linaro volleyed an interesting message to the GCC mailing list on Friday about "LLVM collaboration?" While controversial, he suggested LLVM and GCC developers begin collaborating due to an "unnecessary fence" between the competing compilers and decisions that need to be shared. He acknowledges while there's licensing differences (GPL vs. UIUC / BSD) there's differences between the compilers and their stacks that really shouldn't exist as it hinders the users and developers.
Renato makes known the fact that developers begin relying upon one compiler but then hit roadblocks when trying to compile against the competing compiler for extensions and other changes that are developed in the olpen. He says that there's "decisions that NEED to be shared" when it comes to compiler extensions and other non-standard or undocumented features.
Towards the end of his remarks, Renato Golin says, "For the last year or two, Clang and GCC are approaching an asymptote as to what people believe a toolchain should be, but we won't converge to the same solution unless we talk. If we keep our ideas enclosed inside our own communities, we'll forever fly around the expected target and never reach it. To solve the technical problem of duplicated work we just need to start talking to each other."
Interestingly, this didn't turn into a GCC vs. LLVM flame fest or GPL vs. BSD, but there are developers on both sides of the table interested in better cooperating and proving standards even though they may have their fundamental differences. At the GNU Cauldron 2014 in Cambridge (England) this summer it looks like there may be a GCC + LLVM discussion which some are already calling the "The Open Source Compiler Initiative."
So far the responses to the aforelinked mailing list thread are in support of better cooperation, we will keep monitoring the discussion to see if anything else of interest emerges.