Post #1606372
2026-04-22 01:18 UTC
I need Swift / C interop help!
I want to import a C library into my Swift project. Its type definitions _lie_ about their layout. Some structs have a field `some_c_type data[1];' but the array is actually dynamically sized at runtime. I've marked these structs as SWIFT_NONCOPYABLE and when compiling in Debug mode that's fine. The address of Swift variables of this type are consistent with the address of the C allocation. (1/3)
Replies (1)
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@json@micro.sadlerjw.com 2026-04-22 01:18
In Release mode, it seems that Swift is copying the memory or aliasing it or something - the address of the Swift variable is different than the address of the C allocation. And because the compiler thinks the struct's field is an array of length 1, it doesn't know to copy/alias the right amount of memory. I feel there must be a way to tell the compiler "just use the C memory as-is, where-is" (which is what happens in Debug mode). Anyone have any ideas? (2/3)