+printf "int main(void){return 0;}\n" > minimal.c
+
+printf "Sanity checking C compilation environment... "
+if ${CC} ${CFLAGS} ${CPPFLAGS} minimal.c ${LDFLAGS} -o minimal > /dev/null 2>&1
+then
+ printf "OK.\n"
+else
+ printf "Fail.\n"
+ errors=$((errors + 1))
+fi
+
+printf "Sanity checking C++ compilation environment... "
+if ${CXX} ${CXXFLAGS_for_sh} ${CPPFLAGS} minimal.c ${LDFLAGS} -o minimal > /dev/null 2>&1
+then
+ printf "OK.\n"
+else
+ printf "Fail.\n"
+ errors=$((errors + 1))
+fi
+
+if [ $errors -gt 0 ]; then
+ cat <<EOF
+*** Error: Initial sanity checking of environment failed. Please try
+running configure in a clean environment, and if the problem persists,
+report a bug.
+EOF
+ rm -f minimal minimal.c
+ exit 1
+fi
+
+printf "Reading libnotmuch version from source... "
+cat > _libversion.c <<EOF
+#include <stdio.h>
+#include "lib/notmuch.h"
+int main(void) {
+ printf("libnotmuch_version_major=%d\n",
+ LIBNOTMUCH_MAJOR_VERSION);
+ printf("libnotmuch_version_minor=%d\n",
+ LIBNOTMUCH_MINOR_VERSION);
+ printf("libnotmuch_version_release=%d\n",
+ LIBNOTMUCH_MICRO_VERSION);
+ return 0;
+}
+EOF
+if ${CC} ${CFLAGS} _libversion.c -o _libversion > /dev/null 2>&1 && \
+ ./_libversion > _libversion.sh && . ./_libversion.sh
+then
+ printf "OK.\n"
+else
+ cat <<EOF
+
+*** Error: Reading lib/notmuch.h failed.
+Please try running configure again in a clean environment, and if the
+problem persists, report a bug.
+EOF
+ rm -f _libversion _libversion.c _libversion.sh
+ exit 1
+fi