+# ==================================================================
+gl_other_headers_ ?= \
+ intprops.h \
+ openat.h \
+ stat-macros.h
+
+# Perl -lne code to extract "significant" cpp-defined symbols from a
+# gnulib header file, eliminating a few common false-positives.
+gl_extract_significant_defines_ = \
+ /^\# *define ([^_ (][^ (]*)(\s*\(|\s+\w+)/\
+ && $$2 !~ /(?:rpl_|_used_without_)/\
+ && $$1 !~ /^(?:NSIG|ATTRIBUTE_NORETURN)$$/\
+ and print $$1
+
+# Create a list of regular expressions matching the names
+# of macros that are guaranteed to be defined by parts of gnulib.
+define def_sym_regex
+ gen_h=$(gl_generated_headers_); \
+ (cd $(gnulib_dir)/lib; \
+ for f in *.in.h $(gl_other_headers_); do \
+ perl -lne '$(gl_extract_significant_defines_)' $$f; \
+ done; \
+ ) | sort -u \
+ | grep -Ev '^ATTRIBUTE_NORETURN' \
+ | sed 's/^/^ *# *(define|undef) */;s/$$/\\>/'
+endef
+
+# Don't define macros that we already get from gnulib header files.
+sc_prohibit_always-defined_macros:
+ @if test -d $(gnulib_dir); then \
+ case $$(echo all: | grep -l -f - Makefile) in Makefile);; *) \
+ echo '$(ME): skipping $@: you lack GNU grep' 1>&2; exit 0;; \
+ esac; \
+ $(def_sym_regex) | grep -E -f - $$($(VC_LIST_EXCEPT)) \
+ && { echo '$(ME): define the above via some gnulib .h file' \
+ 1>&2; exit 1; } || :; \
+ fi
+# ==================================================================
+