How to use gcc 4.2 with Xcode 4.2

I need to use gcc 4.2 with Xcode 4.2 for some older code. How do i get it to show up. Xcode4.2 seems to have dropped support for it.

Thanks

Here is a way to enable compiling with gcc 4.2 in xcode 4.2. This is mostly done via command line so when you see lines starting with: [ 15:30 jon@MacBookPro / ]$, you need to open up Terminal.app and run the command that starts after the $.

No files or directories are removed or deleted in this process, so it is easy to undo if you need to compile with LLVM in the future.

Download - but do not install yet - xcode_4.1_for_lion.dmg or xcode_4.1_for_snow_leopard.dmg
Now, follow these steps to install Xcode 4.1 into /Developer-4.1:
1. Backup the working /Developer directory (where Xcode 4.2 is installed)
Run the Xcode 4.1 installer using the default install location (/Developer)

Move the new Xcode 4.1 installation to /Developer-4.1:

[ 15:30 jon@MacBookPro / ]$ sudo mv -v /Developer /Developer-4.1

Move the Xcode 4.2 developer directory back to /Developer:

[ 15:30 jon@MacBookPro / ]$ sudo mv -v /Developer-4.2 /Developer

Edit the Xcode 4.2 GCC 4.2.xcspec file to get gcc 4.2 to show in the list of compiler options ^[1]:

[ 15:30 jon@MacBookPro / ]$ sudo vi "/Developer/Library/Xcode/PrivatePlugIns/Xcode3Core.ideplugin/Contents/SharedSupport/Developer/Library/Xcode/Plug-ins/GCC 4.2 (Plausible Blocks).xcplugin/Contents/Resources/GCC 4.2.xcspec"

Change lines 41 and 42 from this:

ShowInCompilerSelectionPopup = NO;
IsNoLongerSupported = YES;

To This:

ShowInCompilerSelectionPopup = YES; 
IsNoLongerSupported = NO;

Backup the Xcode 4.2 iOS/Simulator Framework usr directories:

[ 15:30 jon@MacBookPro / ]$ sudo mv -v /Developer/Platforms/iPhoneOS.platform/Developer/usr /Developer/Platforms/iPhoneOS.platform/Developer/usr.backup
[ 15:30 jon@MacBookPro / ]$ sudo mv -v /Developer/Platforms/iPhoneSimulator.platform/Developer/usr /Developer/Platforms/iPhoneSimulator.platform/Developer/usr.backup

Copy Xcode 4.1 iOS/Simulator Framework usr directories to Xcode 4.2:

[ 15:30 jon@MacBookPro / ]$ sudo cp -rv /Developer-4.1/Platforms/iPhoneOS.platform/Developer/usr /Developer/Platforms/iPhoneOS.platform/Developer/usr
[ 15:30 jon@MacBookPro / ]$ sudo cp -rv /Developer-4.1/usr /Developer/Platforms/iPhoneSimulator.platform/Developer/usr

Copy the gcc and info iOS SDK library directories from Xcode 4.1 to Xcode 4.2 ^[2]:

[ 15:30 jon@MacBookPro / ]$ sudo cp -rv /Developer-4.1/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk/usr/lib/gcc /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.0.sdk/usr/lib/gcc
[ 15:30 jon@MacBookPro / ]$ sudo cp -rv /Developer-4.1/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk/usr/lib/info /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.0.sdk/usr/lib/info

Compile using gcc-4.2!

This is a blog post I've written with a little more info about this process. Feel free to leave a comment on the blog if you run into any issues or have any questions.

^[1] If opening from a command line (using something like vi, emacs, nano, etc) make sure to either enclose the path in quotes "/long path/with spaces/in it/file.xcspec" or escape the spaces /some/long\ path/with\ spaces/in\ it/file.xcspec

^[2] This is necessary because the iPhoneOS.platform SDK has its own seperate /usr/lib directories but the iPhoneSimulator.platform SDK does not

So the full process for getting gcc 4.2 to work with a fresh install of Xcode 4.2 (non-iOS) is:

Install gcc 4.2
```
sudo port install apple-gcc42
```

Tweak Xcode so that gcc 4.2 appears as a compiler option, by editing the Xcode 4.2 GCC 4.2.xcspec file to get gcc 4.2 to show in the list of compiler options:

Open the xcspec file for editing:

sudo vi "/Developer/Library/Xcode/PrivatePlugIns/Xcode3Core.ideplugin/Contents/SharedSupport/Developer/Library/Xcode/Plug-ins/GCC 4.2.xcplugin/Contents/Resources/GCC 4.2.xcspec"

Change lines 41 and 42 from this:

ShowInCompilerSelectionPopup = NO;
IsNoLongerSupported = YES;

To This:

ShowInCompilerSelectionPopup = YES;
IsNoLongerSupported = NO;

Link the gcc 4.2 binary to the location that Xcode expects:

sudo ln -s /opt/local/bin/gcc-apple-4.2 /Developer/usr/bin/gcc-4.2
sudo ln -s /opt/local/bin/g++-apple-4.2 /Developer/usr/bin/g++-4.2

I explained the problem and workaround in this blog post, which condenses the information I found. Feel free to comment.

Thanks chown for sharing this! I struggled around half a day, but at the end it turned out, that I only needed a few steps to achieve my goal:

For everyone that just needs GCC-4.2 to compile apps (no iOS stuff) it's pretty easy: You don't need to install anything just follow these few steps:

EDIT: If you don't have GCC 4.2 installed already (from an earlier version of Xcode, or manual install), follow the instruciotns from Sean DeNigris in the comments!
Follow step 3 from the original description:
Edit the Xcode 4.2 GCC 4.2.xcspec file to get gcc 4.2 to show in the list of compiler options.
Make Xcode find the compiler again:

ln -s /usr/bin/gcc-4.2 /Developer/usr/bin/gcc-4.2
Also make the linker available:

ln -s /usr/bin/g++-4.2 /Developer/usr/bin/g++-4.2

This works perfectly for me! But as I said it's just for non iOS products!

Simple and userful solution https://github.com/kennethreitz/osx-gcc-installer/ It automates the lists of the declaration on the stackoverflow

来源：https://stackoverflow.com/questions/7786302/how-to-use-gcc-4-2-with-xcode-4-2

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xcode4.2

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