Ah, I see. That makes sense.

On Tuesday, September 24, 2013 12:36:22 PM UTC-7, Ian Lance Taylor wrote:

On Tue, Sep 24, 2013 at 12:16 PM, <thebroke...@gmail.com <javascript:>>
Hi, I am trying to use the zlib library in Go using Cgo (yes, I know there
is a zlib library in Go, but I needed some advanced functionality only the C
version provides), but I was unable to compile my test program. When I try
to compile I get the following error:

# command-line-arguments
1: error: 'inflateInit' undeclared (first use in this function)
1: note: each undeclared identifier is reported only once for each function
it appears in

On the interwebs, it seems the most common issue with undeclared functions
is due to incorrectly included headers, but I think I have done so

// #cgo LDFLAGS: -lz
// #include "zlib.h"
import "C"

Does anyone know why the following block fails to compile?

var strm C.z_stream
strm.zalloc = C.alloc_func(unsafe.Pointer(uintptr(C.Z_NULL)))
strm.zfree = C.free_func(unsafe.Pointer(uintptr(C.Z_NULL)))
strm.opaque = C.voidpf(uintptr(C.Z_NULL))
strm.avail_in = 0
strm.next_in = (*C.Bytef)(unsafe.Pointer(uintptr(C.Z_NULL)))
zerr(C.inflateInit(&strm)) // Fails here due to inflateInit not being
defer C.inflateEnd(&strm)

I'm fairly sure the zlib.h header is being included. If I remove the
inflateInit call, it compiles properly even though there are references to
other functions and structs in zlib.h like inflateEnd and z_stream. I should
note that if I create a C source wrapper around all the functions I use, and
then use the wrapper functions in Cgo, it magically works.
Is this a bug in cgo?
At least in the zlib.h on my system, inflateInit is a macro.
Unfortunately cgo does not support calling macros directly. You have
to use a C wrapper, as you tried.

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postedSep 24, '13 at 7:16p
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