+# Add -Wstack-usage if the compiler is a sufficiently recent version of GCC.
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+__GNUC__
+_ACEOF
+if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
+ $EGREP "^[0-4]$" >/dev/null 2>&1; then :
+
+else
+ GCC_WARN_CFLAGS="$GCC_WARN_CFLAGS -Wstack-usage=262144"
+fi
+rm -f conftest*
+
+
+# Set WARN_WRITE_STRINGS if the compiler supports -Wwrite-strings.
+WARN_WRITE_STRINGS=""
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+__GNUC__
+_ACEOF
+if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
+ $EGREP "^[0-3]$" >/dev/null 2>&1; then :
+
+else
+ WARN_WRITE_STRINGS="-Wwrite-strings"
+fi
+rm -f conftest*
+
+
+# Verify CC_FOR_BUILD to be compatible with warning flags
+
+# Add -Wshadow if the compiler is a sufficiently recent version of GCC.
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+__GNUC__
+_ACEOF
+if (eval "$ac_cpp_for_build conftest.$ac_ext") 2>&5 |
+ $EGREP "^[0-3]$" >/dev/null 2>&1; then :
+
+else
+ GCC_WARN_CFLAGS_FOR_BUILD="$GCC_WARN_CFLAGS_FOR_BUILD -Wshadow"
+fi
+rm -f conftest*
+
+
+# Add -Wstack-usage if the compiler is a sufficiently recent version of GCC.
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+__GNUC__
+_ACEOF
+if (eval "$ac_cpp_for_build conftest.$ac_ext") 2>&5 |
+ $EGREP "^[0-4]$" >/dev/null 2>&1; then :
+
+else
+ GCC_WARN_CFLAGS_FOR_BUILD="$GCC_WARN_CFLAGS_FOR_BUILD -Wstack-usage=262144"
+fi
+rm -f conftest*
+
+