what does macosx-version-min imply?

Question

When I pass compiler flag -mmacosx-version-min=10.5, what does it mean? I think it implies the result binary is x86, not ppc, but is it 32 bits or 64 bits? I\'m

Answer 1

This option will be used by the various availability macros placed into the headers. This means that you can require a minimum version of OS, even if you have a more recent SDK (i.e. target 10.5 with a 10.6 SDK). Using a 10.6 API while targetting 10.5 will trigger a warning and the API will be linked with a weak_import attribute.

Most Apple's API headers contains availability macros for each class, methods, functions or enumerations in order to declare for each of them:

• The minimum OS supported
• The deprecation
• The unavailability
• ...

The macros look like:

• AVAILABLE_MAC_OS_X_VERSION_10_2_AND_LATER
• AVAILABLE_MAC_OS_X_VERSION_10_2_AND_LATER_BUT_DEPRECATED
• ...

As for the architecture, it only depends on the available architectures in the binaries of the SDK. For example with a 10.5 SDK, you can target four architectures (Intel/32bits, PowerPC/32bits, Intel/64bits, PowerPC 64bits), while with a 10.6 SDK, you can only target three architecture (Intel/32bits, PowerPC/32bits, Intel/64bits).

As you are using Snow Leopard, you can either target i386 (Intel/32bits), ppc (PowerPC/32bits) or x86_64 (Intel/64bits) very simply by passing an architecture option like this:

gcc -arch i386

or like this (for configure-based projects):

CFLAGS="-arch i386" LDFLAGS="-arch i386" ./configure

Answer 2

It triggers compiler warnings for methods that appeared after Mac OS X 10.5. Is has nothing to do with architecture.

Answer 3

-mmacosx-version-min=... also influences the default choice of C++ STL implementation (GNU or LLVM), and in this regard, it is equally important for the compiler and the linker.

Answer 4

From my testing, it's also important that this option be passed to the link step (like -arch); so it does more than affect macros/preprocessing (as might be inferred from other answers).

When passed to compile step but not passed to the link step, I found that shared libraries built with 10.6 would not load under 10.5.