OSX: make fails with unrecognized command line option "-Wcovered-switch-default"

[swatanabe]

Reverted to cmake 2.8.6, ran the usual cmake and make steps and ran into this:

[ 5%] Building C object lib/Support/CMakeFiles/LLVMSupport.dir/regerror.c.o
cc1: error: unrecognized command line option "-Wcovered-switch-default"
make[2]: *** [lib/Support/CMakeFiles/LLVMSupport.dir/regcomp.c.o] Error 1
make[2]: *** Waiting for unfinished jobs....
cc1: error: unrecognized command line option "-Wcovered-switch-default"
make[2]: *** [lib/Support/CMakeFiles/LLVMSupport.dir/regerror.c.o] Error 1

This failure is reminiscent of a problem recently reported to clang-dev:
http://lists.cs.uiuc.edu/pipermail/cfe-dev/2012-October/024748.html
which resulted in this reply:
http://lists.cs.uiuc.edu/pipermail/cfe-dev/2012-October/024753.html
which states:

this is a guess, but it's possible you're setting the C++
compiler to clang++, but not setting the C compiler to clang.

This appears to be the case.

-- Check for working C compiler: /usr/bin/gcc
-- Check for working C compiler: /usr/bin/gcc -- works
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works

And on the system that I'm working on, the various c and c++ paths look like this.

$ for p in gcc g++ llvm-gcc-4.2 llvm-g++-4.2 /usr/llvm-gcc-4.2/bin/llvm-gcc-4.2 /usr/llvm-gcc-4.2/bin/llvm-g++-4.2 clang clang++ cc c++; do ls -l which $p; done
lrwxr-xr-x 1 root wheel 12 Oct 16 13:44 /usr/bin/gcc -> llvm-gcc-4.2
lrwxr-xr-x 1 root wheel 12 Oct 16 13:44 /usr/bin/g++ -> llvm-g++-4.2
lrwxr-xr-x 1 root wheel 32 Oct 16 13:44 /usr/bin/llvm-gcc-4.2 -> ../llvm-gcc-4.2/bin/llvm-gcc-4.2
lrwxr-xr-x 1 root wheel 32 Oct 16 13:44 /usr/bin/llvm-g++-4.2 -> ../llvm-gcc-4.2/bin/llvm-g++-4.2
-rwxr-xr-x 1 root wheel 117168 Oct 16 13:44 /usr/llvm-gcc-4.2/bin/llvm-gcc-4.2
-rwxr-xr-x 1 root wheel 117168 Oct 16 13:44 /usr/llvm-gcc-4.2/bin/llvm-g++-4.2
-rwxr-xr-x 1 root wheel 21622640 Oct 16 13:44 /usr/bin/clang
lrwxr-xr-x 1 root wheel 5 Oct 16 13:44 /usr/bin/clang++ -> clang
lrwxr-xr-x 1 root wheel 5 Oct 16 13:44 /usr/bin/cc -> clang
lrwxr-xr-x 1 root wheel 7 Oct 16 13:44 /usr/bin/c++ -> clang++

We see that the "C" compiler choice resolves to /usr/bin/gcc (/usr/llvm-gcc-4.2/bin/llvm-gcc-4.2) and the "CXX" compiler resolves to /usr/bin/c++ (clang++).

The question is: what cmake incantation do I need to work around this issue? For example, I'd like to set CC to 'clang'.
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#1

Updated by Gary Funck 3 months ago
Comment

Gary Funck wrote:

The question is: what cmake incantation do I need to work around this issue?
For example, I'd like to set CC to 'clang'.

I think that I found the answer here:
http://www.cmake.org/Wiki/CMake_Useful_Variables

I can set the CC and CXX environment variables when running cmake. Will try that.

[nenadv]

I cloned the latest tree of llvm-upc and clang-upc. I was able to pass this point by doing the following on Mac:

CC=/usr/bin/cc CXX=/usr/bin/c++ cmake ../src/llvm

OR

cmake -DCMAKE_C_COMPILER=/usr/bin/cc -DCMAKE_CXX_COMPILER=/usr/bin/c++ ../src/llvm

[swatanabe]

Okay, so I can close this?