[pcre-dev] [Bug 2769] r1315: apple_update_wx_flags() calls …

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Author: admin
To: pcre-dev
Subject: [pcre-dev] [Bug 2769] r1315: apple_update_wx_flags() calls unavailable API when compiling to deploy on older macOS

--- Comment #2 from Rich Siegel <siegel@???> ---
Calling an unavailable API is never a NOP. You'll get a runtime error from dyld
which ends up calling abort() on any OS which doesn't implement it. It looks
like this:

dyld: Symbol not found: _pthread_jit_write_protect_np
Referenced from: /path/to/app/executable
Expected in: /usr/lib/libSystem.B.dylib

If compiler compatibility is more than a theoretical issue, it should be
possible to further conditionalize the call as needed:

#ifdef __has_builtin
#if __has_builtin(builtin_available)
// do the work

If you're not compiling with a version of Xcode which includes a version of
clang which supports __builtin_availble(), it's a given that you can't call
pthread_jit_write_protect_np() because it won't exist in the SDK.

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