duplicates:

• SR-397 Linux - module using <dispatch/dispatch.h> does not compile cleanly with "swift build"

Issue Description:

I wanted to do some code in C because of missing support in Swift (try to use a socket interface, that casting is horrible) so I did the "complex" part in C and just wanted to call back into swift with the data.

If you use a C-Function pointer as callback interface you'll get:
"error: a C function pointer cannot be formed from a closure that captures context"

that sounds reasonable so i tried to use a clang block callback but then i get:
"error: blocks support disabled - compile with -fblocks or pick a deployment target that supports them"

I know for compiling my C test program that uses the interface I have to link against "BlocksRuntime" and compile with "-fBlocks" but how do I set the compile parameter with "swift build"?

If you want to see what I want to do look here: https://github.com/dunkelstern/libUnchainedSocket

(current github checkin with tag 0.0.1 has the c function pointer interface, see branch "blocks" for the blocks version, you'll need "libblocksruntime-dev")