configure: check that C++ compiler actually works
Check that the C++ compiler works with the C compiler; if it
does not, then don't pass CXX to the build process. This
fixes a regression where QEMU was no longer building if the
build environment didn't have a C++ compiler (introduced
in commit 3144f78b, which incorrectly assumed that rules.mak
would only see a non-empty $(CXX) if configure had actually
found a working C++ compiler).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reported-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Tested-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-id: 1392909016-14028-1-git-send-email-peter.maydell@linaro.org
diff --git a/configure b/configure
index 39f2a1a..352a9c7 100755
--- a/configure
+++ b/configure
@@ -1289,6 +1289,35 @@
error_exit "\"$cc\" either does not exist or does not work"
fi
+# Check that the C++ compiler exists and works with the C compiler
+if has $cxx; then
+ cat > $TMPC <<EOF
+int c_function(void);
+int main(void) { return c_function(); }
+EOF
+
+ compile_object
+
+ cat > $TMPC <<EOF
+extern "C" {
+ int c_function(void);
+}
+int c_function(void) { return 42; }
+EOF
+
+ if (cc=$cxx do_cc $QEMU_CFLAGS -o $TMPE $TMPC $TMPO $LDFLAGS); then
+ # C++ compiler $cxx works ok with C compiler $cc
+ :
+ else
+ echo "C++ compiler $cxx does not work with C compiler $cc"
+ echo "Disabling C++ specific optional code"
+ cxx=
+ fi
+else
+ echo "No C++ compiler available; disabling C++ specific optional code"
+ cxx=
+fi
+
# Consult white-list to determine whether to enable werror
# by default. Only enable by default for git builds
z_version=`cut -f3 -d. $source_path/VERSION`
