[bug-gettext] [PATCH] Add support for msgmerge --previous

[Stanislav Brabec]

msgmerge --previous is a very useful feature that makes adjusting of
translation much easier when small changes in the source code are done.
msgmerge supports it for 10 years, but it is not used by most projects,
as Makefile.in.in never added support for it.

Use msgmerge --previous as default on all systems with gettext >= 0.16.

---
 NEWS                              |  3 +++
 gettext-runtime/po/Makefile.in.in | 16 ++++++++++------
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/NEWS b/NEWS
index bbbf1e3..83f1280 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,6 @@
+* Runtime behaviour:
+  - update-po target in Makefile.in.in now uses msgfmt --previous.
+
 Version 0.19.8 - June 2016
 
 * Support for reproducible builds:
diff --git a/gettext-runtime/po/Makefile.in.in 
b/gettext-runtime/po/Makefile.in.in
index 38c293d..44ec103 100644
--- a/gettext-runtime/po/Makefile.in.in
+++ b/gettext-runtime/po/Makefile.in.in
@@ -232,13 +232,15 @@ $(POFILES): $(POFILESDEPS)
        if test -f "$(srcdir)/$${lang}.po"; then \
          test -f $(srcdir)/$(DOMAIN).pot || $(MAKE) $(srcdir)/$(DOMAIN).pot; \
          test "$(srcdir)" = . && cdcmd="" || cdcmd="cd $(srcdir) && "; \
-         echo "$${cdcmd}$(MSGMERGE_UPDATE) $(MSGMERGE_OPTIONS) --lang=$${lang} 
$${lang}.po $(DOMAIN).pot"; \
+         echo "$${cdcmd}$(MSGMERGE_UPDATE) $(MSGMERGE_OPTIONS) --lang=$${lang} 
--previous $${lang}.po $(DOMAIN).pot"; \
          cd $(srcdir) \
            && { case `$(MSGMERGE) --version | sed 1q | sed -e 's,^[^0-9]*,,'` 
in \
-                  '' | 0.[0-9] | 0.[0-9].* | 0.1[0-7] | 0.1[0-7].*) \
+                  '' | 0.[0-9] | 0.[0-9].* | 0.1[0-5] | 0.1[0-5].*) \
                     $(MSGMERGE_UPDATE) $(MSGMERGE_OPTIONS) $${lang}.po 
$(DOMAIN).pot;; \
+                  0.1[6-7] | 0.1[6-7].*) \
+                    $(MSGMERGE_UPDATE) $(MSGMERGE_OPTIONS) --previous 
$${lang}.po $(DOMAIN).pot;; \
                   *) \
-                    $(MSGMERGE_UPDATE) $(MSGMERGE_OPTIONS) --lang=$${lang} 
$${lang}.po $(DOMAIN).pot;; \
+                    $(MSGMERGE_UPDATE) $(MSGMERGE_OPTIONS) --lang=$${lang} 
--previous $${lang}.po $(DOMAIN).pot;; \
                 esac; \
               }; \
        else \
@@ -439,13 +441,15 @@ update-po: Makefile
        tmpdir=`pwd`; \
        echo "$$lang:"; \
        test "$(srcdir)" = . && cdcmd="" || cdcmd="cd $(srcdir) && "; \
-       echo "$${cdcmd}$(MSGMERGE) $(MSGMERGE_OPTIONS) --lang=$$lang $$lang.po 
$(DOMAIN).pot -o $$lang.new.po"; \
+       echo "$${cdcmd}$(MSGMERGE) $(MSGMERGE_OPTIONS) --lang=$$lang --previous 
$$lang.po $(DOMAIN).pot -o $$lang.new.po"; \
        cd $(srcdir); \
        if { case `$(MSGMERGE) --version | sed 1q | sed -e 's,^[^0-9]*,,'` in \
-              '' | 0.[0-9] | 0.[0-9].* | 0.1[0-7] | 0.1[0-7].*) \
+              '' | 0.[0-9] | 0.[0-9].* | 0.1[0-5] | 0.1[0-5].*) \
                 $(MSGMERGE) $(MSGMERGE_OPTIONS) -o $$tmpdir/$$lang.new.po 
$$lang.po $(DOMAIN).pot;; \
+              0.1[6-7] | 0.1[6-7].*) \
+                $(MSGMERGE) $(MSGMERGE_OPTIONS) --previous -o 
$$tmpdir/$$lang.new.po $$lang.po $(DOMAIN).pot;; \
               *) \
-                $(MSGMERGE) $(MSGMERGE_OPTIONS) --lang=$$lang -o 
$$tmpdir/$$lang.new.po $$lang.po $(DOMAIN).pot;; \
+                $(MSGMERGE) $(MSGMERGE_OPTIONS) --lang=$$lang --previous -o 
$$tmpdir/$$lang.new.po $$lang.po $(DOMAIN).pot;; \
             esac; \
           }; then \
          if cmp $$lang.po $$tmpdir/$$lang.new.po >/dev/null 2>&1; then \
-- 
2.8.4

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
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