Do not allow identifiers that start with a dash.

This cleans up our previous fixes for a bug whereby Bison
discarded `.field' in `$-1.field'.  The previous fixes were less
restrictive about where a dash could appear in an identifier, but
the restrictions were hard to explain.  That bug was reported and
this final fix was originally suggested by Paul Hilfinger.  This
also fixes a remaining bug reported by Paul Eggert whereby Bison
parses `%token ID -123' as `%token ID - 123' and handles `-' as an
identifier.  Now, `-' cannot be an identifier.  Discussed in
threads beginning at
<http://lists.gnu.org/archive/html/bug-bison/2011-01/msg00000.html>,
<http://lists.gnu.org/archive/html/bug-bison/2011-01/msg00004.html>.
* NEWS (2.5): Update entry describing the dash extension to
grammar symbol names.  Also, move that entry before the named
references entry because the latter mentions the former.
* doc/bison.texinfo (Symbol): Update documentation for symbol
names.  As suggested by Paul Eggert, mention the effect of periods
and dashes on named references.
(Decl Summary): Update documentation for unquoted %define values,
which, as a side effect, can no longer start with dashes either.
* src/scan-code.l (id): Implement.
* src/scan-gram.l (id): Implement.
* tests/actions.at (Exotic Dollars): Extend test group to exercise
bug reported by Paul Hilfinger.
* tests/input.at (Symbols): Update test group, and extend to
exercise bug reported by Paul Eggert.
* tests/named-refs.at (Stray symbols in brackets): Update test
group.
($ or @ followed by . or -): Likewise.
* tests/regression.at (Invalid inputs): Likewise.

1 files changed, 16 insertions, 11 deletions

diff --git a/tests/named-refs.at b/tests/named-refs.at
index 74549c6e..3c7b072d 100644
--- a/tests/named-refs.at
+++ b/tests/named-refs.at
@@ -446,13 +446,14 @@ AT_SETUP([Stray symbols in brackets])
 AT_DATA_GRAMMAR([test.y],
 [[
 %%
-start: foo[ /* aaa */ *&-+ ] bar
+start: foo[ /* aaa */ *&-.+ ] bar
   { s = $foo; }
 ]])
 AT_BISON_CHECK([-o test.c test.y], 1, [],
 [[test.y:11.23: invalid character in bracketed name: `*'
 test.y:11.24: invalid character in bracketed name: `&'
-test.y:11.26: invalid character in bracketed name: `+'
+test.y:11.25: invalid character in bracketed name: `-'
+test.y:11.27: invalid character in bracketed name: `+'
 ]])
 AT_CLEANUP
 
@@ -570,23 +571,27 @@ AT_DATA([[test.y]],
 %%
 start:
   .field { $.field; }
-| -field { @-field; }
 | 'a'    { @.field; }
-| 'a'    { $-field; }
 ;
 .field: ;
--field: ;
 ]])
 AT_BISON_CHECK([[test.y]], [[1]], [],
 [[test.y:4.12-18: invalid reference: `$.field'
 test.y:4.13:        syntax error after `$', expecting integer, letter, `_', `@<:@', or `$'
 test.y:4.3-8:       possibly meant: $[.field] at $1
-test.y:5.12-18: invalid reference: `@-field'
+test.y:5.12-18: invalid reference: `@.field'
 test.y:5.13:        syntax error after `@', expecting integer, letter, `_', `@<:@', or `$'
-test.y:5.3-8:       possibly meant: @[-field] at $1
-test.y:6.12-18: invalid reference: `@.field'
-test.y:6.13:        syntax error after `@', expecting integer, letter, `_', `@<:@', or `$'
-test.y:7.12-18: invalid reference: `$-field'
-test.y:7.13:        syntax error after `$', expecting integer, letter, `_', `@<:@', or `$'
+]])
+AT_DATA([[test.y]],
+[[
+%%
+start:
+  'a' { $-field; }
+| 'b' { @-field; }
+;
+]])
+AT_BISON_CHECK([[test.y]], [[0]], [],
+[[test.y:4.9: warning: stray `$'
+test.y:5.9: warning: stray `@'
 ]])
 AT_CLEANUP