>From e22bc6279b9659e39d2e0d8589bc735ea8a2893d Mon Sep 17 00:00:00 2001
From: Bernhard Voelker <address@hidden>
Date: Fri, 4 Jan 2019 21:46:14 +0100
Subject: [PATCH] build: use distributed man pages when running with --help
 fails

When building against an incompatible GLIBC version compared to that
on the build host, then running the just-built binary might fail
although it is the same platform - thus CROSS_COMPILING is false.
As a result, generating the man pages fails.

* man/local.mk (.x.1): Add a check to verify that running the utility
with --help succeeds, otherwise falling back to using 'dummy-man'.
---
 man/local.mk | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/man/local.mk b/man/local.mk
index eee38396c..ee74d1f9b 100644
--- a/man/local.mk
+++ b/man/local.mk
@@ -191,9 +191,16 @@ endif
 	  && $(MKDIR_P) $$t						\
 	  && (cd $$t && $(LN_S) '$(abs_top_builddir)/src/'$$prog$(EXEEXT) \
 				$$argv$(EXEEXT))			\
-	&& : $${SOURCE_DATE_EPOCH=`cat $(srcdir)/.timestamp 2>/dev/null || :`} \
+	  || exit 1;							\
+## Double-check whether the built binary succeeds with --help as the above
+## CROSS_COMPILING condition might have been wrong in some cases, e.g. when
+## building against an incompatible glibc version on the same platform.
+	$$t/$$argv$(EXEEXT) --help </dev/null >/dev/null		\
+	  && run_help2man="$(run_help2man)"				\
+	  || run_help2man="$(srcdir)/man/dummy-man";			\
+	: $${SOURCE_DATE_EPOCH=`cat $(srcdir)/.timestamp 2>/dev/null || :`} \
 	&& : $${TZ=UTC0} && export TZ					\
-	&& export SOURCE_DATE_EPOCH && $(run_help2man)			\
+	&& export SOURCE_DATE_EPOCH && $${run_help2man}			\
 		     --source='$(PACKAGE_STRING)'			\
 		     --include=$(srcdir)/man/$$name.x			\
 		     --output=$$t/$$name.1				\
-- 
2.20.1