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c++iosczlibxcode15

Xcode 15 compile error: Import of C++ module 'zlib' appears within extern "C" language linkage specification

I am trying to compile an existing project with Xcode 15 RC, the project uses some dependencies that internally use zlib.

zlib.h is included using

#ifdef __cplusplus
extern "C" {
#endif

#ifndef _ZLIB_H
#include "zlib.h"
#endif
...

I get this error: Import of C++ module 'zlib' appears within extern "C" language linkage specification

Everything was working fine on Xcode 14. Is zlib a c++ library now?

I can move the includes out of the extern "C" scope, but my I have POD dependencies failing and I don't have control over them, I can try using cocoapods-patch but I wonder if there is an easier way to solve this problem.

Solution

  • extern "C" { is a C++ feature that is invalid in C and further code in that block is expected to be C.

    zlib.h has own extern "C" {, and when you include zlib.h in extern "C" { you get nested extern "C" { and the compiler warns you about that: C++ code is met where C code is expected.

    Don't include zlib.h in extern "C" { block, move the last after all inclusions.