From facdea659083095a6ec8bcc7aa322f683898739b Mon Sep 17 00:00:00 2001
From: Bruno Haible <bruno@clisp.org>
Date: Sun, 22 Dec 2019 21:12:52 +0100
Subject: build: Don't erase the .sym file if 'sed' is not GNU sed.

* lib/Makefile.am (libunistring.sym): Test the exit status of the
declared.sh command. Preserve the existing libunistring.sym if it
failed.
---
 ChangeLog       |  7 +++++++
 lib/Makefile.am | 26 +++++++++++++++++---------
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index c52f289..ca1ca30 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2019-12-22  Bruno Haible  <bruno@clisp.org>
+
+	build: Don't erase the .sym file if 'sed' is not GNU sed.
+	* lib/Makefile.am (libunistring.sym): Test the exit status of the
+	declared.sh command. Preserve the existing libunistring.sym if it
+	failed.
+
 2019-12-22  Bruno Haible  <bruno@clisp.org>
 
 	build: Update after gnulib changed.
diff --git a/lib/Makefile.am b/lib/Makefile.am
index aa32f57..3798a0a 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -242,16 +242,24 @@ HEADERS_WITH_EXTERNS = \
 # '-export-symbols', but we don't use this option, because it would prevent us
 # from building some of the gnulib unit tests.
 $(srcdir)/libunistring.sym : $(HEADERS_WITH_EXTERNS)
-	for f in $(HEADERS_WITH_EXTERNS); do \
-	  if test -f $$f; then \
-	    cat $$f; \
+	if \
+	  for f in $(HEADERS_WITH_EXTERNS); do \
+	    if test -f $$f; then \
+	      cat $$f; \
+	    else \
+	      cat $(srcdir)/$$f; \
+	    fi; \
+	  done \
+	  | $(srcdir)/declared.sh > $@-t1; \
+	then \
+	  LC_ALL=C sort < $@-t1 | LC_ALL=C uniq > $@-t2 && mv $@-t2 $@; \
+	else \
+	  if test -f $@; then \
+	    echo "Continuing with existing libunistring.sym."; \
 	  else \
-	    cat $(srcdir)/$$f; \
+	    exit 1; \
 	  fi; \
-	done \
-	  | $(srcdir)/declared.sh | LC_ALL=C sort | LC_ALL=C uniq \
-	  > $@-t
-	mv $@-t $@
+	fi
 # We distribute it because declared.sh relies on GNU sed.
 # The GNU Coding Standards say in
 # <https://www.gnu.org/prep/standards/html_node/Makefile-Basics.html>:
@@ -261,7 +269,7 @@ $(srcdir)/libunistring.sym : $(HEADERS_WITH_EXTERNS)
 #    So Makefile rules to update them should put the updated files in the
 #    source directory."
 # Therefore we put this file in the source directory, not the build directory.
-MOSTLYCLEANFILES     += libunistring.sym-t
+MOSTLYCLEANFILES     += libunistring.sym-t1 libunistring.sym-t2
 MAINTAINERCLEANFILES += libunistring.sym
 EXTRA_DIST           += libunistring.sym declared.sh
 
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