Sink the autoconf check for sufficiently modern host toolchain below the

enable flag that selects the C++ standard library to use with the host
toolchain. Otherwise we end up testing the wrong config.

I'm not really happy about this placement, but its pragmatic and should
unblock the Apple builders.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199325 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 260 insertions, 260 deletions

diff --git a/configure b/configure
index a1b63f8888..0f03eace1e 100755
--- a/configure
+++ b/configure
@@ -1395,11 +1395,11 @@ if test -n "$ac_init_help"; then
 Optional Features:
   --disable-FEATURE       do not include FEATURE (same as --enable-FEATURE=no)
   --enable-FEATURE[=ARG]  include FEATURE [ARG=yes]
+  --enable-polly          Use polly if available (default is YES)
+  --enable-libcpp         Use libc++ if available (default is NO)
   --enable-compiler-version-checks
                           Check the version of the host compiler (default is
                           YES)
-  --enable-polly          Use polly if available (default is YES)
-  --enable-libcpp         Use libc++ if available (default is NO)
   --enable-cxx11          Use c++11 if available (default is NO)
   --enable-split-dwarf    Use split-dwarf if available (default is NO)
   --enable-clang-arcmt    Enable building of clang ARCMT (default is YES)
@@ -3702,264 +3702,6 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 { echo "$as_me:$LINENO: result: ${llvm_cv_cxx_compiler}" >&5
 echo "${ECHO_T}${llvm_cv_cxx_compiler}" >&6; }
 
-# Check whether --enable-compiler-version-checks was given.
-if test "${enable_compiler_version_checks+set}" = set; then
-  enableval=$enable_compiler_version_checks;
-else
-  enableval=default
-fi
-
-case "$enableval" in
-  no)
-    ;;
-  yes|default)
-    ac_ext=cpp
-ac_cpp='$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
-
-    case "$llvm_cv_cxx_compiler" in
-    clang)
-      { echo "$as_me:$LINENO: checking whether Clang is new enough" >&5
-echo $ECHO_N "checking whether Clang is new enough... $ECHO_C" >&6; }
-      cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-
-#if __clang_major__ < 3 || (__clang_major__ == 3 && __clang_minor__ < 1)
-#error This version of Clang is too old to build LLVM
-#endif
-
-_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:$LINENO: error:
-The selected Clang compiler is not new enough to build LLVM. Please upgrade to
-Clang 3.1. You may pass --disable-compiler-version-checks to configure to
-bypass these sanity checks." >&5
-echo "$as_me: error:
-The selected Clang compiler is not new enough to build LLVM. Please upgrade to
-Clang 3.1. You may pass --disable-compiler-version-checks to configure to
-bypass these sanity checks." >&2;}
-   { (exit 1); exit 1; }; }
-fi
-
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-
-                              { echo "$as_me:$LINENO: checking whether Clang will select a modern C++ standard library" >&5
-echo $ECHO_N "checking whether Clang will select a modern C++ standard library... $ECHO_C" >&6; }
-      llvm_cv_old_cxxflags="$CXXFLAGS"
-      CXXFLAGS="$CXXFLAGS -std=c++0x"
-      cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-
-#include <atomic>
-std::atomic<float> x(0.0f);
-int main() { return (float)x; }
-
-_ACEOF
-rm -f conftest.$ac_objext conftest$ac_exeext
-if { (ac_try="$ac_link"
-case "(($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_link") 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_exeext'
-  { (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:$LINENO: error:
-We detected a missing feature in the standard C++ library that was known to be
-missing in libstdc++4.6 and implemented in libstdc++4.7. There are numerous
-C++11 problems with 4.6's library, and we don't support GCCs or libstdc++ older
-than 4.7. You will need to update your system and ensure Clang uses the newer
-standard library.
-
-If this error is incorrect or you need to force things to work, you may pass
-'--disable-compiler-version-checks' to configure to bypass this test." >&5
-echo "$as_me: error:
-We detected a missing feature in the standard C++ library that was known to be
-missing in libstdc++4.6 and implemented in libstdc++4.7. There are numerous
-C++11 problems with 4.6's library, and we don't support GCCs or libstdc++ older
-than 4.7. You will need to update your system and ensure Clang uses the newer
-standard library.
-
-If this error is incorrect or you need to force things to work, you may pass
-'--disable-compiler-version-checks' to configure to bypass this test." >&2;}
-   { (exit 1); exit 1; }; }
-fi
-
-rm -f core conftest.err conftest.$ac_objext \
-      conftest$ac_exeext conftest.$ac_ext
-      CXXFLAGS="$llvm_cv_old_cxxflags"
-      ;;
-    gcc)
-      { echo "$as_me:$LINENO: checking whether GCC is new enough" >&5
-echo $ECHO_N "checking whether GCC is new enough... $ECHO_C" >&6; }
-      cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-
-#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
-#error This version of GCC is too old to build LLVM
-#endif
-
-_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:$LINENO: error:
-The selected GCC C++ compiler is not new enough to build LLVM. Please upgrade
-to GCC 4.7. You may pass --disable-compiler-version-checks to configure to
-bypass these sanity checks." >&5
-echo "$as_me: error:
-The selected GCC C++ compiler is not new enough to build LLVM. Please upgrade
-to GCC 4.7. You may pass --disable-compiler-version-checks to configure to
-bypass these sanity checks." >&2;}
-   { (exit 1); exit 1; }; }
-fi
-
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-      ;;
-    unknown)
-      ;;
-    esac
-    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
-
-    ;;
-  *)
-    { { echo "$as_me:$LINENO: error: Invalid setting for --enable-compiler-version-checks. Use \"yes\" or \"no\"" >&5
-echo "$as_me: error: Invalid setting for --enable-compiler-version-checks. Use \"yes\" or \"no\"" >&2;}
-   { (exit 1); exit 1; }; }
-    ;;
-esac
-
 
 
 if test -d ${srcdir}/projects/test-suite ; then
@@ -4790,6 +4532,264 @@ echo "$as_me: error: Invalid setting for --enable-libcpp. Use \"yes\" or \"no\""
    { (exit 1); exit 1; }; } ;;
 esac
 
+# Check whether --enable-compiler-version-checks was given.
+if test "${enable_compiler_version_checks+set}" = set; then
+  enableval=$enable_compiler_version_checks;
+else
+  enableval=default
+fi
+
+case "$enableval" in
+  no)
+    ;;
+  yes|default)
+    ac_ext=cpp
+ac_cpp='$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
+
+    case "$llvm_cv_cxx_compiler" in
+    clang)
+      { echo "$as_me:$LINENO: checking whether Clang is new enough" >&5
+echo $ECHO_N "checking whether Clang is new enough... $ECHO_C" >&6; }
+      cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#if __clang_major__ < 3 || (__clang_major__ == 3 && __clang_minor__ < 1)
+#error This version of Clang is too old to build LLVM
+#endif
+
+_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:$LINENO: error:
+The selected Clang compiler is not new enough to build LLVM. Please upgrade to
+Clang 3.1. You may pass --disable-compiler-version-checks to configure to
+bypass these sanity checks." >&5
+echo "$as_me: error:
+The selected Clang compiler is not new enough to build LLVM. Please upgrade to
+Clang 3.1. You may pass --disable-compiler-version-checks to configure to
+bypass these sanity checks." >&2;}
+   { (exit 1); exit 1; }; }
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+                              { echo "$as_me:$LINENO: checking whether Clang will select a modern C++ standard library" >&5
+echo $ECHO_N "checking whether Clang will select a modern C++ standard library... $ECHO_C" >&6; }
+      llvm_cv_old_cxxflags="$CXXFLAGS"
+      CXXFLAGS="$CXXFLAGS -std=c++0x"
+      cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#include <atomic>
+std::atomic<float> x(0.0f);
+int main() { return (float)x; }
+
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (ac_try="$ac_link"
+case "(($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_link") 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_exeext'
+  { (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:$LINENO: error:
+We detected a missing feature in the standard C++ library that was known to be
+missing in libstdc++4.6 and implemented in libstdc++4.7. There are numerous
+C++11 problems with 4.6's library, and we don't support GCCs or libstdc++ older
+than 4.7. You will need to update your system and ensure Clang uses the newer
+standard library.
+
+If this error is incorrect or you need to force things to work, you may pass
+'--disable-compiler-version-checks' to configure to bypass this test." >&5
+echo "$as_me: error:
+We detected a missing feature in the standard C++ library that was known to be
+missing in libstdc++4.6 and implemented in libstdc++4.7. There are numerous
+C++11 problems with 4.6's library, and we don't support GCCs or libstdc++ older
+than 4.7. You will need to update your system and ensure Clang uses the newer
+standard library.
+
+If this error is incorrect or you need to force things to work, you may pass
+'--disable-compiler-version-checks' to configure to bypass this test." >&2;}
+   { (exit 1); exit 1; }; }
+fi
+
+rm -f core conftest.err conftest.$ac_objext \
+      conftest$ac_exeext conftest.$ac_ext
+      CXXFLAGS="$llvm_cv_old_cxxflags"
+      ;;
+    gcc)
+      { echo "$as_me:$LINENO: checking whether GCC is new enough" >&5
+echo $ECHO_N "checking whether GCC is new enough... $ECHO_C" >&6; }
+      cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
+#error This version of GCC is too old to build LLVM
+#endif
+
+_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:$LINENO: error:
+The selected GCC C++ compiler is not new enough to build LLVM. Please upgrade
+to GCC 4.7. You may pass --disable-compiler-version-checks to configure to
+bypass these sanity checks." >&5
+echo "$as_me: error:
+The selected GCC C++ compiler is not new enough to build LLVM. Please upgrade
+to GCC 4.7. You may pass --disable-compiler-version-checks to configure to
+bypass these sanity checks." >&2;}
+   { (exit 1); exit 1; }; }
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+      ;;
+    unknown)
+      ;;
+    esac
+    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
+
+    ;;
+  *)
+    { { echo "$as_me:$LINENO: error: Invalid setting for --enable-compiler-version-checks. Use \"yes\" or \"no\"" >&5
+echo "$as_me: error: Invalid setting for --enable-compiler-version-checks. Use \"yes\" or \"no\"" >&2;}
+   { (exit 1); exit 1; }; }
+    ;;
+esac
+
 # Check whether --enable-cxx11 was given.
 if test "${enable_cxx11+set}" = set; then
   enableval=$enable_cxx11;