Thread: LLVM __COUNTER__ Macro not expanding

Hi everybody,

I'm using the LLVM compiler at the moment. I've written the following (test) code:

Code:

#define F2(x, y) x##y 
#define F1(x, y) F2(x, y)
#define TEST(x) F1(x, __COUNTER__)

TEST(abc) 
TEST(abc)

I don't actually compile this code, but I preprocess it using "gcc -E". The output becomes:

Code:

abc__COUNTER__
abc__COUNTER__

However, when I change __COUNTER__ to __LINE__, it does work:

Code:

abc5
abc6

Am I doing something wrong here? __LINE__ just doesn't cut it for me in this situation...

Thanks in advance!

Actually, it seems that __COUNTER__ doesn't work at all. It seemed to work when I compiled with "make", as my Mac is a bit of a mess with several compilers installed. But even a basic app like this:

Code:

#include <stdio.h>

int main()
{
  printf("%d %d\n", __COUNTER__, __COUNTER__);
}

Doesn't seem to expand __COUNTER__. Any idea why? My compiler version is:

$ gcc -v
Using built-in specs.
Target: i686-apple-darwin11
Configured with: /private/var/tmp/llvmgcc42/llvmgcc42-2336.11~67/src/configure --disable-checking --enable-werror --prefix=/Applications/Xcode.app/Contents/Developer/usr/llvm-gcc-4.2 --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-prefix=llvm- --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with-slibdir=/usr/lib --build=i686-apple-darwin11 --enable-llvm=/private/var/tmp/llvmgcc42/llvmgcc42-2336.11~67/dst-llvmCore/Developer/usr/local --program-prefix=i686-apple-darwin11- --host=x86_64-apple-darwin11 --target=i686-apple-darwin11 --with-gxx-include-dir=/usr/include/c++/4.2.1
Thread model: posix
gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00)

As provided by Apple's command line tools.

IMO, it's working as __LINE__, is a global directive and __COUNTER__ is being expanded to the __LINE__ number of the code, as in

Code:

abc5
abc6

Or if I didn't get it then explain yourself better

Originally Posted by itCbitC

IMO, it's working as __LINE__, is a global directive and __COUNTER__ is being expanded to the __LINE__ number of the code, as in

Code:

abc5
abc6

Or if I didn't get it then explain yourself better

Yes, __LINE__ worked, __COUNTER__ didn't. As I explained in the second post, __COUNTER__ isn't expanded at all (it did work with make as it used gcc, it didn't with gcc as it used llvm). But according to the documents, LLVM should support __COUNTER__.

__LINE__ isn't good enough for a unique identifier, as that may still cause conflicting names through multiple files.

Take a look here, which says that __COUNTER__ macro is found only in gcc release 4.3 and above.

Originally Posted by itCbitC

Take a look here, which says that __COUNTER__ macro is found only in gcc release 4.3 and above.

I don't think that is correct. Clang Language Extensions

Code:

$ gcc --version
gcc (Ubuntu/Linaro 4.6.1-9ubuntu3) 4.6.1
$ cat test.c
#define F2(x, y) x##y
#define F1(x, y) F2(x, y)
#define TEST(x) F1(x, __COUNTER__)
 
TEST(abc)
TEST(abc)
$ gcc -E test.c | tail -n 2
abc0
abc1

Bye, Andreas

Originally Posted by Codeplug

>> I don't think that is correct. ...

>> $ gcc -v ...

Never used it myself, but if clang were being used, I would expect the command line to use "clang" instead of "gcc".

gg

Right. I didn't even know I had the "clang" command. Mac's a bit of a mess compiler wise. See:

Code:

$ cat /tmp/a.c 
#define F2(x, y) x##y 
#define F1(x, y) F2(x, y)
#define TEST(x) F1(x, __COUNTER__)
 
TEST(abc) 
TEST(abc)

Now the info about the available compilers:

Code:

$ ls -al /usr/bin/gcc 
lrwxr-xr-x  1 root  wheel  12 24 Oct 13:52 /usr/bin/gcc -> llvm-gcc-4.2
$ ls -al /usr/bin/clang
-rwxr-xr-x  1 root  wheel  21622640 24 Oct 13:52 /usr/bin/clang
$ clang -v
Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
Target: x86_64-apple-darwin12.2.0
Thread model: posix
$ gcc -v
Using built-in specs.
Target: i686-apple-darwin11
Configured with: /private/var/tmp/llvmgcc42/llvmgcc42-2336.11~67/src/configure --disable-checking --enable-werror --prefix=/Applications/Xcode.app/Contents/Developer/usr/llvm-gcc-4.2 --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-prefix=llvm- --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with-slibdir=/usr/lib --build=i686-apple-darwin11 --enable-llvm=/private/var/tmp/llvmgcc42/llvmgcc42-2336.11~67/dst-llvmCore/Developer/usr/local --program-prefix=i686-apple-darwin11- --host=x86_64-apple-darwin11 --target=i686-apple-darwin11 --with-gxx-include-dir=/usr/include/c++/4.2.1
Thread model: posix
gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00)

As for the compilation:

Code:

$ clang -E /tmp/a.c 
# 1 "/tmp/a.c"
# 1 "/tmp/a.c" 1
# 1 "<built-in>" 1
# 1 "<built-in>" 3
# 147 "<built-in>" 3
# 1 "<command line>" 1
# 1 "<built-in>" 2
# 1 "/tmp/a.c" 2




abc0
abc1

And:

Code:

$ llvm-gcc -E /tmp/a.c 
# 1 "/tmp/a.c"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "/tmp/a.c"




abc__COUNTER__
abc__COUNTER__

So I do have "LLVM" and "clang" separately, where clang works fine and LLVM doesn't.

I thought clang was part of LLVM, but now I don't know what LLVM is even supposed to be anymore. It seems to simply be an old version of gcc, though... Apple's compiler infrastructure is a mess... I guess I'll just stop using that compiler (or whatever it may be).


Thanks for your replies, guys!

llvm-gcc is a front end for LLVM based on gcc 4.2.x (where I can't remember the x). That puts it as older than the 4.3 needed to have the __COUNTER__ macro added to gcc. Clang is a gcc-alike front end for LLVM that's actively being developed, so it probably copied GCC4.3's addition of __COUNTER__ development.