As other's have noted, GCC has a plugin system (and not a [edit:stable] external interface) -- so that extensions/tools (plugins) will have to link to GCC, and be covered by the GPL. This is similar to how the Linux kernel tries to limit binary drivers, by explicitly not having a stable ABI (although, in the case of the Linux kernel I <i>think</i> it is also a case of "we don't want the burden of maintaining an outdated, inferior ABI for the sake your proprietary crap -- share or GTFO (And it's easier for everyone if we can just see your code, bugs and all)").<p>However, isn't this paragraph:<p>"I also think it bears noticing that nobody outside of Microsoft seems
to particularly want to write proprietary compilers any more. GCC won
its war; the cost and time-to-market advantages of hooking into
open-source toolchains are now so widely understood that new processor
designs support them as a matter of course."<p>proved wrong by Apple's Xcode? Isn't that exactly what Aplle is (partially) doing? I know Apple makes great contributions to (among other projects, clang) -- but is upstream clang the same as what comes with Xcode?