Don't force CC=cc (if CC is not defined) for all installing phase

[sorah]

(Continuing from a0570c9's commit comment)

What's the commit

a0570c9

• This meaning to force clang by specifying CC=cc if CC isn't set, because ruby-2.0.0-p0 build fails on llvm-gcc
  • cc is symlinked to clang, but gcc symlinked to llvm-gcc and llvm-gcc make failures.
  • ruby-2.0.0-p0 uses gcc for default, so llvm-gcc will be used. and currently build will be failed with llvm-gcc.
  • Here's must read about OS X's C compiler background: 2.0.0-rc2 build failed #290 (comment)

Problems

• Segmentation faults on 1.8 because 1.8 doesn't support clang.

So, I recommend to...

• Add comment that like "this is forcing to clang due to 2.0.0-p0's problem"
• Use CC=clang instead of CC=cc
• check platform, or gcc is llvm-gcc
• Move CC=clang into 2.0.0-p0 file, because 1.8 doesn't support clang and it makes SEGV on 1.8.

[sorah]

@sstephenson oh, Sorry I don't know require_gcc.

But, I still think we should check gcc = llvm-gcc and this workaround should be only in 2.0.0-p0.

How about that change?

[nurse]

Ruby 2.0.0 can choice suitable compiler from gcc-4.2, clang, gcc, and cc in configure.in by itself.
see https://github.com/ruby/ruby/blob/v2_0_0_0/configure.in#L373

Ruby 1.8.7-p371 supports clang (r36253).

[jeremy]

OK - the issue we had with Ruby's auto-detect is that gcc-4.2 may be symlinked to llvm-gcc, which resulted in build failures.

Sounds like we can set CFLAGS to fix that issue, instead.

[sorah]

What? I don't know an environment which gcc-4.2 = llvm-gcc, normally it just not exists by default.

It should be users' problem.

[jeremy]

I may be remembering wrong. Confusing 😁

[nurse]

gcc-4.2 is always GNU GCC. cc/gcc can be llvm-gcc.

[sstephenson]

Fixed - thank you.