# GCC >= 4.4 supports UTF16 string literals. The CFLAGS and CXXFLAGS may change in the future.

if test "$CHECK_UTF16_STRING_RESULT" = "unknown"; then

    if test "$GCC" = yes; then

        OLD_CFLAGS="${CFLAGS}"

        CFLAGS="${CFLAGS} -std=gnu99"

        AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[

static const char16_t test[] = u"This is a UTF16 literal string.";

        ]], [[]])],[CC_UTF16_STRING=1],[CC_UTF16_STRING=0])

        if test "$CC_UTF16_STRING" = 1; then

            CHECK_UTF16_STRING_RESULT="C only";

        else

            CFLAGS="${OLD_CFLAGS}"

        fi

    fi

    if test "$GXX" = yes; then

        OLD_CXXFLAGS="${CXXFLAGS}"

        # -Wno-return-type-c-linkage is desired so that stable ICU API is not warned about.

        CXXFLAGS="${CXXFLAGS} -std=c++11"

        AC_LANG_PUSH([C++])

        AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[

static const char16_t test[] = u"This is a UTF16 literal string.";

        ]], [[]])],[CXX_UTF16_STRING=1],[CXX_UTF16_STRING=0])

        AC_LANG_POP([C++])

        if test "$CXX_UTF16_STRING" = 1; then

            if test "$CC_UTF16_STRING" = 1; then

                CHECK_UTF16_STRING_RESULT="available";

            else

                CHECK_UTF16_STRING_RESULT="C++ only";

            fi

        else

            CXXFLAGS="${OLD_CXXFLAGS}"

        fi

    fi

fi

AC_MSG_RESULT($CHECK_UTF16_STRING_RESULT)