From 22970f8ac1f173d882139e4dccc7831871252f47 Mon Sep 17 00:00:00 2001
From: =?utf8?q?P=C3=A1draig=20Brady?= <P@draigBrady.com>
Date: Mon, 25 Jan 2010 10:55:34 +0000
Subject: [PATCH] syntax-check: detect incorrect boolean macro values in
 config.h

* modules/maintainer-makefile (configure.ac): Parameterize the location
of config.h which will be available to makefiles as $(CONFIG_INCLUDE).
The logic is from Eric Blake and the location indicated by Jim Meyering.
Note the more natural CONFIG_HEADER name is prohibited by automake
for backwards compatibility reasons.
* top/maint.mk (sc_Wundef_boolean): New rule.
---
 ChangeLog                   | 10 ++++++++++
 modules/maintainer-makefile |  4 ++++
 top/maint.mk                |  8 ++++++++
 3 files changed, 22 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 2c79e308c8..5d82d10891 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2010-01-25 Pádraig Brady <P@draigBrady.com>
+
+	syntax-check: detect incorrect boolean macro values in config.h
+	* modules/maintainer-makefile (configure.ac): Parameterize the location
+	of config.h which will be available to makefiles as $(CONFIG_INCLUDE).
+	The logic is from Eric Blake and the location indicated by Jim Meyering.
+	Note the more natural CONFIG_HEADER name is prohibited by automake
+	for backwards compatibility reasons.
+	* top/maint.mk (sc_Wundef_boolean): New rule.
+
 2010-01-25  Jim Meyering  <meyering@redhat.com>
 
 	bootstrap: detect MacOS 10.6's shasum, too
diff --git a/modules/maintainer-makefile b/modules/maintainer-makefile
index 21c28020ec..ed43e8790a 100644
--- a/modules/maintainer-makefile
+++ b/modules/maintainer-makefile
@@ -9,6 +9,10 @@ gnumakefile
 useless-if-before-free
 vc-list-files
 
+configure.ac:
+AC_CONFIG_COMMANDS_PRE([m4_ifdef([AH_HEADER],
+  [AC_SUBST([CONFIG_INCLUDE], m4_defn([AH_HEADER]))])])
+
 License:
 GPLed build tool
 
diff --git a/top/maint.mk b/top/maint.mk
index 346d6813bd..d384ca62b2 100644
--- a/top/maint.mk
+++ b/top/maint.mk
@@ -718,6 +718,14 @@ sc_copyright_check:
 	       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.
+# So at least preclude common boolean strings as macro values.
+sc_Wundef_boolean:
+	@grep -Ei '^#define.*(yes|no|true|false)$$' '$(CONFIG_INCLUDE)' && \
+	  { echo 'Use 0 or 1 for macro values' 1>&2; exit 1; } || :
+
 vc-diff-check:
 	(unset CDPATH; cd $(srcdir) && $(VC) diff) > vc-diffs || :
 	if test -s vc-diffs; then				\
-- 
2.30.2