[groff] 32/33: [tbl]: Fix Savannah #63838.

[G. Branden Robinson]

gbranden pushed a commit to branch branden-post-1.23.0
in repository groff.

commit d036588d6528d712d390e1e6769303aedb6e67a7
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Sat Feb 25 18:44:58 2023 -0600

    [tbl]: Fix Savannah #63838.
    
    * src/preproc/tbl/table.cpp (table::add_entry): Throw error diagnostic
      if table entry ends in the zero-motion escape sequence `\z`.  This is
      nonsense and provokes baffling diagnostics from the formatter.  Stick
      user's nose directly into the problem.
    
    Fixes <https://savannah.gnu.org/bugs/?63838>.  Thanks to the mandoc(1)
    project for documenting the issue in a regression test.
    
    Also annotate a null pointer with `nullptr` comment to ease any future
    transition to C++11, which defines it as a keyword.
---
 src/preproc/tbl/table.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/preproc/tbl/table.cpp b/src/preproc/tbl/table.cpp
index c391c90ae..a12874d2b 100644
--- a/src/preproc/tbl/table.cpp
+++ b/src/preproc/tbl/table.cpp
@@ -1513,7 +1513,14 @@ void table::add_entry(int r, int c, const string &str,
                      const entry_format *f, const char *fn, int ln)
 {
   allocate(r);
-  table_entry *e = 0;
+  table_entry *e = 0 /* nullptr */;
+  int len = str.length();
+  if (len > 1) {
+    string last_two_chars = str.substring((len - 2), 2);
+    if ("\\z" == last_two_chars)
+      error_with_file_and_line(fn, ln, "table entry ends with"
+                              " zero-motion escape sequence");
+  }
   char *s = str.extract();
   if (str.search('\n') >= 0) {
     bool was_changed = false;