Configure: if we compile with clang, check that it is not broken

Some linux distibutions (for example, Mageia 2, Fedora 17) ship Clang that is
essentially broken for the end user.  Clang can not find or compile libstdc++
headers.

The issue is that our configure prefers clang over gcc, thus selecting a broken
Clang when a working GCC is available.

Now we detect this issue by compiling a simple program.  If it does not
compile, configure stops with an error suggesting the user to select a
different compiler.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171975 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 93 insertions, 2 deletions

diff --git a/configure b/configure
index 4392e97..3ca2df9 100755
--- a/configure
+++ b/configure
@@ -3471,6 +3471,98 @@ ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
+if test "$CXX" = "clang++" ; then
+  { echo "$as_me:$LINENO: checking whether clang works" >&5
+echo $ECHO_N "checking whether clang works... $ECHO_C" >&6; }
+  ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
+
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <limits>
+#if __has_include (<cxxabi.h>)
+#include <cxxabi.h>
+#endif
+#if __has_include (<unwind.h>)
+#include <unwind.h>
+#endif
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_cxx_werror_flag" || test ! -s conftest.err'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+
+  { echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+  { echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+  { { echo "$as_me:$LINENO: error: Selected compiler could not find or parse C++ standard library headers.  Rerun with CC=c-compiler CXX=c++-compiler ./configure ..." >&5
+echo "$as_me: error: Selected compiler could not find or parse C++ standard library headers.  Rerun with CC=c-compiler CXX=c++-compiler ./configure ..." >&2;}
+   { (exit 1); exit 1; }; }
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+fi
+
 
 
 if test -d ${srcdir}/projects/llvm-gcc ; then
@@ -10393,7 +10485,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<EOF
-#line 10396 "configure"
+#line 10488 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -16330,7 +16422,6 @@ rm -f core conftest.err conftest.$ac_objext \
 
 
 
-
   { echo "$as_me:$LINENO: checking for HUGE_VAL sanity" >&5
 echo $ECHO_N "checking for HUGE_VAL sanity... $ECHO_C" >&6; }
 if test "${ac_cv_huge_val_sanity+set}" = set; then