* lib/quote.h, lib/quote.c, lib/quotearg.h, lib/quotearg.c:

* m4/prereq.m4, m4/c-bs-a.m4, m4/mbstate.m4:
New files, from Fileutils 4.0.27.
* src/main.c (printable_version): Remove.
* src/lex.c, src/reader.c: Use `quote'.


* lib/error.c, lib/error.h: New files, needed by xmalloc.c.

tests/regression.m4

@@ -24,3 +24,29 @@ exp: '(' exp ')' | NUM ;
 AT_CHECK([bison -v duplicate.y -o duplicate.c], 0, ignore, ignore)
 
 AT_CLEANUP(duplicate.*)
+#                                                        -*- Autoconf -*-
+
+cat <<EOF
+
+Regression tests.
+
+EOF
+
+AT_SETUP(Duplicate string)
+
+AT_DATA([duplicate.y],
+[[/* `Bison -v' used to dump core when two tokens are defined with the same
+   string, as LE and GE below. */
+
+%token NUM
+%token LE "<="
+%token GE "<="
+
+%%
+exp: '(' exp ')' | NUM ;
+%%
+]])
+
+AT_CHECK([bison -v duplicate.y -o duplicate.c], 0, ignore, ignore)
+
+AT_CLEANUP(duplicate.*)