--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2010-04-07  Jim Meyering  <meyering@redhat.com>
+
+	maint.mk: add a PATH crosschecking syntax-check rule
+	* top/maint.mk (sc_cross_check_PATH_usage_in_tests): New rule.
+	Useful if you use a test like the one in help-version (coreutils,
+	diffutils, grep, gzip) that ensures $(VERSION) matches what is
+	printed by prog --version.
+
 2010-04-06  Bruno Haible  <bruno@clisp.org>
 
 	Fix link error on mingw.

--- a/top/maint.mk
+++ b/top/maint.mk
@@ -849,6 +849,26 @@
 	halt='out of date copyright in $(texi); update it'		\
 	  $(_sc_search_regexp)
 
+# If tests/help-version exists and seems to be new enough, assume that its
+# use of init.sh and path_prepend_ is correct, and ensure that every other
+# use of init.sh is identical.
+# This is useful because help-version cross-checks prog --version
+# with $(VERSION), which verifies that its path_prepend_ invocation
+# sets PATH correctly.  This is an inexpensive way to ensure that
+# the other init.sh-using tests also get it right.
+_hv_file ?= $(srcdir)/tests/help-version
+_hv_regex ?= ^ *\. [^ ]*/init\.sh
+sc_cross_check_PATH_usage_in_tests:
+	@if grep -l 'VERSION mismatch' $(_hv_file) >/dev/null		\
+	    && grep -lE '$(_hv_regex)' $(_hv_file) >/dev/null; then	\
+	  good=$$(grep -E '$(_hv_regex)' < $(_hv_file));		\
+	  grep -LFx "$$good"						\
+		$$(grep -lE '$(_hv_regex)' $$($(VC_LIST_EXCEPT)))	\
+	      | grep . &&						\
+	    { echo "$(ME): the above files use path_prepend_ inconsistently" \
+		1>&2; exit 1; } || :;					\
+	fi
+
 # #if HAVE_... will evaluate to false for any non numeric string.
 # That would be flagged by using -Wundef, however gnulib currently
 # tests many undefined macros, and so we can't enable that option.