[PATCH] maint.mk: also prohibit "#undef" of always-defined symbols

[Jim Meyering]

I noticed some #undef uses that were made obsolete by gnulib use,
so tweaked this syntax-check rule to spot them, just like it does
for #define'd symbols:

>From 8b4add2c64d10b260c21352768e22d41dc9d2ff7 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Thu, 27 May 2010 13:33:04 +0200
Subject: [PATCH] maint.mk: also prohibit "#undef" of always-defined symbols

* top/maint.mk (def_sym_regex): Handle #undef as well as #define.
Allow more than one space before the symbol name.
(sc_prohibit_always-defined_macros): Use grep's -E, now that
the regexp uses alternation.
---
 ChangeLog    |    8 ++++++++
 top/maint.mk |    5 +++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 1ee9575..6a54e63 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2010-05-27  Jim Meyering  <address@hidden>
+
+       maint.mk: also prohibit "#undef" of always-defined symbols
+       * top/maint.mk (def_sym_regex): Handle #undef as well as #define.
+       Allow more than one space before the symbol name.
+       (sc_prohibit_always-defined_macros): Use grep's -E, now that
+       the regexp uses alternation.
+
 2010-05-26  Eric Blake  <address@hidden>

        maint.mk: avoid echo -e
diff --git a/top/maint.mk b/top/maint.mk
index 045537f..644fbb6 100644
--- a/top/maint.mk
+++ b/top/maint.mk
@@ -689,7 +689,8 @@ define def_sym_regex
            perl -lne '$(gl_extract_significant_defines_)' $$f;         \
          done;                                                         \
        ) | sort -u                                                     \
-         | sed 's/^/^ *# *define /;s/$$/\\>/'
+         | grep -Ev '^ATTRIBUTE_NORETURN'                              \
+         | sed 's/^/^ *# *(define|undef)  */;s/$$/\\>/'
 endef

 # Don't define macros that we already get from gnulib header files.
@@ -698,7 +699,7 @@ sc_prohibit_always-defined_macros:
          case $$(echo all: | grep -l -f - Makefile) in Makefile);; *)  \
            echo '$(ME): skipping $@: you lack GNU grep' 1>&2; exit 0;; \
          esac;                                                         \
-         $(def_sym_regex) | grep -f - $$($(VC_LIST_EXCEPT))            \
+         $(def_sym_regex) | grep -E -f - $$($(VC_LIST_EXCEPT))         \
            && { echo '$(ME): define the above via some gnulib .h file' \
                  1>&2;  exit 1; } || :;                                \
        fi
--
1.7.1.348.gb26ba