FSF GCC on Darwin does not create “fat” object files; it creates an object file for the single architecture that GCC was built to target. Apple's GCC on Darwin does create “fat” files if multiple -arch options are used; it does so by running the compiler or linker multiple times and joining the results together with lipo .
The subtype of the file created (like ‘ ppc7400 ’ or ‘ ppc970 ’ or ‘ i686 ’) is determined by the flags that specify the ISA that GCC is targeting, like -mcpu or -march . The -force_cpusubtype_ALL option can be used to override this.
The Darwin tools vary in their behavior when presented with an ISA mismatch. The assembler, as , only permits instructions to be used that are valid for the subtype of the file it is generating, so you cannot put 64-bit instructions in a ‘ ppc750 ’ object file. The linker for shared libraries, /usr/bin/libtool , fails and prints an error if asked to create a shared library with a less restrictive subtype than its input files (for instance, trying to put a ‘ ppc970 ’ object file in a ‘ ppc7400 ’ library). The linker for executables, ld , quietly gives the executable the most restrictive subtype of any of its input files.
A framework directory is a directory with frameworks in it. A framework is a directory with a
directory contained directly in it that ends in
. The name of a framework is the name of this directory excluding the
. Headers associated with the framework are found in one of those two directories, with
being searched first. A subframework is a framework directory that is in a framework's
directory. Includes of subframework headers can only appear in a header of a framework that contains the subframework, or in a sibling subframework header. Two subframeworks are siblings if they occur in the same framework. A subframework should not have the same name as a framework; a warning is issued if this is
violated. Currently a subframework cannot have subframeworks; in the future, the mechanism may be extended to support this. The standard frameworks can be found in
. An example include looks like
denotes the name of the framework and
is found in the
If the compiler was built to use the system's headers by default, then the default for this option is the system version on which the compiler is running, otherwise the default is to make choices that are compatible with as many systems and code bases as possible.
sizeof(bool)==1. By default
4when compiling for Darwin/PowerPC and
1when compiling for Darwin/x86, so this option has no effect on x86.
switch causes GCC to generate code that is not binary compatible with code generated without that switch. Using this switch may require recompiling all other modules in a program, including system libraries. Use this switch to conform to a non-default data model.