[FYI] {maint} texi: warn against '.txi' and '.texinfo' input suffixes

[Stefano Lattarini]

The warning being in the 'obsolete' category.  This is mostly to
ease transition to Automake-NG (see commit v1.12.1-416-gd5459b9),
and to discourage use of seldom-tested setups.

* automake.in (handle_texinfo_helper): Warn against Texinfo input
files with '.txi' or '.texinfo' suffixes.
* NEWS: Update.
* t/txinfo-other-suffixes.sh: Adjust and enhance.
* t/txinfo-no-repeated-targets.sh: No longer use '.txi' and
'.texinfo' extensions.

Signed-off-by: Stefano Lattarini <address@hidden>
---
 NEWS                            |  5 +++++
 automake.in                     | 16 +++++++++++-----
 t/txinfo-no-repeated-targets.sh |  6 +++---
 t/txinfo-other-suffixes.sh      | 10 ++++++++--
 4 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/NEWS b/NEWS
index 0e5455b..c9ad88a 100644
--- a/NEWS
+++ b/NEWS
@@ -55,6 +55,11 @@ New in 1.13.2:
     '@setfilename' macro in Texinfo input files) is discouraged, and
     its use will raise warnings in the 'obsolete' category.
 
+  - Use of Texinfo input files with '.txi' or '.texinfo' extensions
+    is discouraged, and its use will raise warnings in the 'obsolete'
+    category.  You are advised to simply use the '.texi' extension
+    instead.
+
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 New in 1.13.1:
diff --git a/automake.in b/automake.in
index 386bbf2..7a863cf 100644
--- a/automake.in
+++ b/automake.in
@@ -3146,11 +3146,17 @@ sub handle_texinfo_helper ($)
       ($info_texinfos->value_as_list_recursive (inner_expand => 1))
     {
       my $infobase = $texi;
-      # TODO: In Automake 1.14 (or even 1.13.2), start warning against
-      # TODO: suffixes != ".texi", to ease transition to Automake-NG.
-      $infobase =~ s/\.(txi|texinfo|texi)$//;
-
-      if ($infobase eq $texi)
+      if ($infobase =~ s/\.texi$//)
+        {
+          1; # Nothing more to do.
+        }
+      elsif ($infobase =~ s/\.(txi|texinfo)$//)
+        {
+         msg_var 'obsolete', $info_texinfos,
+                 "suffix '.$1' for Texinfo files is discouraged;" .
+                  " use '.texi' instead";
+        }
+      else
        {
          # FIXME: report line number.
          err_am "texinfo file '$texi' has unrecognized extension";
diff --git a/t/txinfo-no-repeated-targets.sh b/t/txinfo-no-repeated-targets.sh
index c9b977a..99894f5 100755
--- a/t/txinfo-no-repeated-targets.sh
+++ b/t/txinfo-no-repeated-targets.sh
@@ -19,12 +19,12 @@
 . test-init.sh
 
 cat > Makefile.am << 'END'
-info_TEXINFOS = maude.texi liver.txi heart.texinfo
+info_TEXINFOS = maude.texi liver.texi heart.texi
 END
 
 echo '@setfilename maude.info' > maude.texi
-echo '@setfilename liver.info' > liver.txi
-echo '@setfilename heart.info' > heart.texinfo
+echo '@setfilename liver.info' > liver.texi
+echo '@setfilename heart.info' > heart.texi
 : > texinfo.tex
 
 $ACLOCAL
diff --git a/t/txinfo-other-suffixes.sh b/t/txinfo-other-suffixes.sh
index 11f3a04..cbb3afa 100755
--- a/t/txinfo-other-suffixes.sh
+++ b/t/txinfo-other-suffixes.sh
@@ -14,7 +14,8 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-# Test to make sure '.txi' extension works.
+# Test to make sure '.txi' and '.texinfo' extensions are deprecated,
+# but still work.
 
 . test-init.sh
 
@@ -27,7 +28,12 @@ echo '@setfilename bar.info' > bar.texinfo
 : > texinfo.tex
 
 $ACLOCAL
-$AUTOMAKE
+AUTOMAKE_fails
+grep "^Makefile\.am:.*suffix '.txi'.*Texinfo file.*discouraged" stderr
+grep "^Makefile\.am:.*suffix '.texinfo'.*Texinfo file.*discouraged" stderr
+grep "^Makefile\.am:.* use '.texi' instead" stderr
+
+$AUTOMAKE -Wno-obsolete
 
 grep '^\.txi\.info: *$' Makefile.in
 grep '^\.texinfo\.info: *$' Makefile.in
-- 
1.8.1.rc3.27.g3b73c7d