grep: -T no longer outputs BS

* NEWS: Document this (Bug#24451).
* src/grep.c (print_line_head): Do not attempt to backspace output.
* tests/initial-tab: New test.
* tests/Makefile.am (TESTS): Add it.

4 files changed, 42 insertions, 20 deletions

diff --git a/NEWS b/NEWS
index 29a0e8d2..0037edd7 100644
--- a/NEWS
+++ b/NEWS
@@ -16,6 +16,10 @@ GNU grep NEWS                                    -*- outline -*-
 
   grep -m0 -L PAT FILE now outputs "FILE".  [bug introduced in grep-2.5]
 
+  To output ':' and tab-align the following character C, grep -T no
+  longer outputs tab-backspace-':'-C, an approach that has problems if
+  run inside an Emacs shell window.  [bug introduced in grep-2.5.2]
+
   grep's use of getprogname no longer causes a build failure on HP-UX.
 
 ** Improvements
diff --git a/src/grep.c b/src/grep.c
index a794af48..86cf18b9 100644
--- a/src/grep.c
+++ b/src/grep.c
@@ -1134,13 +1134,11 @@ print_line_head (char *beg, size_t len, char const *lim, char sep)
         }
     }
 
-  bool pending_sep = false;
-
   if (out_file)
     {
       print_filename ();
       if (filename_mask)
-        pending_sep = true;
+        print_sep (sep);
       else
         putchar_errno (0);
     }
@@ -1153,34 +1151,21 @@ print_line_head (char *beg, size_t len, char const *lim, char sep)
           totalnl = add_count (totalnl, 1);
           lastnl = lim;
         }
-      if (pending_sep)
-        print_sep (sep);
       print_offset (totalnl, 4, line_num_color);
-      pending_sep = true;
+      print_sep (sep);
     }
 
   if (out_byte)
     {
       uintmax_t pos = add_count (totalcc, beg - bufbeg);
       pos = dossified_pos (pos);
-      if (pending_sep)
-        print_sep (sep);
       print_offset (pos, 6, byte_num_color);
-      pending_sep = true;
-    }
-
-  if (pending_sep)
-    {
-      /* This assumes sep is one column wide.
-         Try doing this any other way with Unicode
-         (and its combining and wide characters)
-         filenames and you're wasting your efforts.  */
-      if (align_tabs)
-        fputs_errno ("\t\b");
-
       print_sep (sep);
     }
 
+  if (align_tabs && (out_file | out_line | out_byte) && len != 0)
+    putchar_errno ('\t');
+
   return true;
 }
 
diff --git a/tests/Makefile.am b/tests/Makefile.am
index b6f0df32..56e860f0 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -108,6 +108,7 @@ TESTS =						\
   in-eq-out-infloop				\
   include-exclude				\
   inconsistent-range				\
+  initial-tab					\
   invalid-multibyte-infloop			\
   khadafy					\
   kwset-abuse					\
diff --git a/tests/initial-tab b/tests/initial-tab
new file mode 100755
index 00000000..af5efb37
--- /dev/null
+++ b/tests/initial-tab
@@ -0,0 +1,32 @@
+#!/bin/sh
+# Exercise -T.
+
+# Copyright 2016 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/init.sh"; path_prepend_ ../src
+
+fail=0
+
+printf 'x\n\n' > in || framework_failure_
+
+grep -T '^' in > out || fail=1
+compare in out || fail=1
+
+printf 'in:\tx\nin:\n' > exp || framework_failure_
+grep -T '^' in /dev/null > out || fail=1
+compare exp out || fail=1
+
+Exit $fail