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Do not allow identifiers that start with a dash.

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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.
This commit is contained in:
Joel E. Denny
2011-01-29 12:54:28 -05:00
parent 676997e53b
commit 82f3355eaf
9 changed files with 123 additions and 35 deletions
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18
doc/bison.texinfo
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@@ -3123,12 +3123,13 @@ A @dfn{nonterminal symbol} stands for a class of syntactically
equivalent groupings. The symbol name is used in writing grammar rules.
By convention, it should be all lower case.
Symbol names can contain letters, underscores, periods, dashes, and (not
at the beginning) digits. Dashes in symbol names are a GNU
extension, incompatible with POSIX Yacc. Terminal symbols
that contain periods or dashes make little sense: since they are not
valid symbols (in most programming languages) they are not exported as
token names.
Symbol names can contain letters, underscores, periods, and non-initial
digits and dashes. Dashes in symbol names are a GNU extension, incompatible
with POSIX Yacc. Periods and dashes make symbol names less convenient to
use with named references, which require brackets around such names
(@pxref{Named References}). Terminal symbols that contain periods or dashes
make little sense: since they are not valid symbols (in most programming
languages) they are not exported as token names.
There are three ways of writing terminal symbols in the grammar:
@@ -5039,9 +5040,8 @@ Define a variable to adjust Bison's behavior.
It is an error if a @var{variable} is defined by @code{%define} multiple
times, but see @ref{Bison Options,,-D @var{name}[=@var{value}]}.
@var{value} must be placed in quotation marks if it contains any
character other than a letter, underscore, period, dash, or non-initial
digit.
@var{value} must be placed in quotation marks if it contains any character
other than a letter, underscore, period, or non-initial dash or digit.
Omitting @code{"@var{value}"} entirely is always equivalent to specifying
@code{""}.