stdenv-darwin: Revert to clang 3.3

In 3.3, a C++ class defined in a header will get a typeinfo symbol
like this (e.g. in Nix's src/libutil/util.o):

  (__DATA,__datacoal_nt) weak external typeinfo for nix::BaseError

But in 3.4, this has changed to:

  (__DATA,__datacoal_nt) weak external automatically hidden typeinfo for nix::BaseError

This causes the linker to change the symbol to:

  (__DATA,__data) non-external (was signed char private external) typeinfo for nix::BaseError

i.e. losing its weak linkage. But without weak linkage, dynamic_cast
and other RTTI-based mechanisms (such as catching an exception of a
certain type) don't work across shared libraries / executables.

The clang compiler in the SDK doesn't have this behaviour, but it's
not clear exactly which version it is (it just says "based on LLVM
3.4svn").

1 files changed, 1 insertions, 1 deletions

diff --git a/pkgs/stdenv/darwin/default.nix b/pkgs/stdenv/darwin/default.nix
index 26114d2726e1..cbc9a38b77de 100644
--- a/pkgs/stdenv/darwin/default.nix
+++ b/pkgs/stdenv/darwin/default.nix
@@ -1,6 +1,6 @@
 { stdenv, pkgs, config
 , haveLibCxx ? true
-, useClang33 ? false }:
+, useClang33 ? true }:
 
 import ../generic rec {
   inherit config;