maintcheck: avoid failures, sync with 'ng/master' more

* syntax-checks.mk (sc_diff_aclocal_in_aclocal,
sc_diff_automake_in_automake): Rename ...
(sc_diff_aclocal, sc_diff_automake): ... respectively to these, rewrite
to use static pattern rules and 'diff -u' instead of bare 'diff'.  This
makes the rules more robust in the face of edits to 'automake.in' and
'aclocal.in', and get them in sync with the corresponding checks in the
'ng/master' branch.
(syntax_check_rules): Adjust.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

1 files changed, 21 insertions, 17 deletions

diff --git a/syntax-checks.mk b/syntax-checks.mk
index a7aaeac20..9a8a7e701 100644
--- a/syntax-checks.mk
+++ b/syntax-checks.mk
@@ -43,8 +43,8 @@ ams := $(shell find $(srcdir) -name '*.dir' -prune -o -name '*.am' -print)
 # guaranteed to work on my machine.
 syntax_check_rules = \
 $(sc_tests_plain_check_rules) \
-sc_diff_automake_in_automake \
-sc_diff_aclocal_in_automake \
+sc_diff_automake \
+sc_diff_aclocal \
 sc_no_brace_variable_expansions \
 sc_rm_minus_f \
 sc_no_for_variable_in_macro \
@@ -79,21 +79,25 @@ sc_tabs_in_texi \
 sc_at_in_texi
 
 ## These check avoids accidental configure substitutions in the source.
-## There are exactly 9 lines that should be modified from automake.in to
-## automake, and 10 lines that should be modified from aclocal.in to
-## aclocal; these wors out to 32 and 34 lines of diffs, respectively.
-sc_diff_automake_in_automake:
-	@if test `diff $(srcdir)/automake.in automake | wc -l` -ne 32; then \
-	  echo "found too many diffs between automake.in and automake" 1>&2; \
-	  diff -c $(srcdir)/automake.in automake; \
-	  exit 1; \
-	fi
-sc_diff_aclocal_in_aclocal:
-	@if test `diff $(srcdir)/aclocal.in aclocal | wc -l` -ne 34; then \
-	  echo "found too many diffs between aclocal.in and aclocal" 1>&2; \
-	  diff -c $(srcdir)/aclocal.in aclocal; \
-	  exit 1; \
-	fi
+## There are exactly 8 lines that should be modified from automake.in to
+## automake, and 9 lines that should be modified from aclocal.in to
+## aclocal.
+automake_diff_no = 8
+aclocal_diff_no = 9
+sc_diff_automake sc_diff_aclocal: sc_diff_% :
+	@set +e; tmp=$*-diffs.tmp; \
+	 diff -u $(srcdir)/$*.in $* > $$tmp; test $$? -eq 1 || exit 1; \
+	 added=`grep -v '^+++ ' $$tmp | grep -c '^+'` || exit 1; \
+	 removed=`grep -v '^--- ' $$tmp | grep -c '^-'` || exit 1; \
+	 test $$added,$$removed = $($*_diff_no),$($*_diff_no) \
+	  || { \
+	    echo "Found unexpected diffs between $*.in and $*"; \
+	    echo "Lines added:   $$added"  ; \
+	    echo "Lines removed: $$removed"; \
+	    cat $$tmp >&2; \
+	    exit 1; \
+	  } >&1; \
+	rm -f $$tmp
 
 ## Expect no instances of '${...}'.  However, $${...} is ok, since that
 ## is a shell construct, not a Makefile construct.