swift234

SIL: Don't reabstract functions with C calling conventions.

Reabstraction doesn't exist in the C world, so even in generic contexts, C functions and blocks have to preserve their usual by-value calling conventions, and to call them generically, we'd have to dynamically form an invocation (but we probably won't bother supporting that for 1.0). More realistically, we can't reabstract a block just to store it in an optional without breaking ABI with ObjC.

Swift SVN r16151