CODEWITHSUNDEEP
c++cmacosgcc
Tokubara
Tokubara

Reputation: 470

How does gcc search framework headers on Mac OSX(10.15)?

By gcc -v I know that gcc searches in these paths:

/usr/local/include
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/11.0.3/include
 /usr/include
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
 /System/Library/Frameworks (framework directory)
 /Library/Frameworks (framework directory)

I write:

#include <CoreFoundation/CoreFoundation.h>
int main() {
        return 0;
}

It gives no error messages. But with the following, gcc cannot find the header.

#include <CoreFoundation.framework/Headers/CoreFoundation.h>
int main() {
        return 0;
}

I know that gcc finds the header CoreFoundation.h in /System/Library/Frameworks. And the path of the header is /System/Library/Frameworks/CoreFoundation.framework/Headers/CoreFoundation.h.

My question is: why #include <CoreFoundation/CoreFoundation.h> is OK? Why not CoreFoundation.framework/Headers/CoreFoundation.h (it gives error messages)? I think it should be CoreFoundation.framework/Headers/CoreFoundation.h, as the full path of the header is /System/Library/Frameworks/CoreFoundation.framework/Headers/CoreFoundation.h, and the inlcude path is /System/Library/Frameworks.

Thanks in advance.

The following may have something to do with this problem.

I compile a file that include 'CoreServices/CoreServices.h'.

did not find header 'CoreServices.h' in framework 'CoreServices' (loaded from '/System/Library/Frameworks')

Then I use gcc -I /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/CoreServices.framework/, because I know the header's path is /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/CoreServices.framework/Headers/CoreServices.h. But it still doesn't work. Why?

Upvotes: 1

Views: 1477

Answers (1)

3CxEZiVlQ
3CxEZiVlQ

Reputation: 38991

Two lines in the gcc -v output is a hint about special directories that are handled not like include directories.

 /System/Library/Frameworks (framework directory)
 /Library/Frameworks (framework directory)

Apple's gcc for Darwing architecture has special extensions for finding include files from framworks. You can read about the Darwin Options

Especially look at -Fdir option. It allows to specify other framework dirs additional to the listed above. This option describes how gcc looks for header files in a framework:

A framework directory is a directory with frameworks in it. A framework is a directory with a Headers and/or PrivateHeaders directory contained directly in it that ends in .framework. The name of a framework is the name of this directory excluding the .framework. Headers associated with the framework are found in one of those two directories, with Headers being searched first. A subframework is a framework directory that is in a framework’s Frameworks 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 /System/Library/Frameworks and /Library/Frameworks. An example include looks like #include <Framework/header.h>, where Framework denotes the name of the framework and header.h is found in the PrivateHeaders or Headers directory.

Upvotes: 4

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