patch for C99; plus NEWS updates

[Paul Eggert]

I installed the following.  The NEWS file was a bit wrong, since the
usage checking is now available only with destructors.  One of our tests
wasn't safe for C99.

2006-02-13  Paul Eggert  <address@hidden>

        * NEWS: Version 2.1a.
        * tests/headers.at (AT_TEST_CPP_GUARD_H): Declare yyerror and yylex,
        since C99 requires this.

Index: NEWS
===================================================================
RCS file: /cvsroot/bison/bison/NEWS,v
retrieving revision 1.141
diff -p -u -r1.141 NEWS
--- NEWS        19 Jan 2006 06:44:49 -0000      1.141
+++ NEWS        13 Feb 2006 19:06:26 -0000
@@ -1,14 +1,14 @@
 Bison News
 ----------
 
-Changes in version 2.1a:
+Changes in version 2.1a, 2006-02-13:
 
 * Bison now allows multiple %union declarations, and concatenates
   their contents together.
 
 * New warning: unused values
-  Typed right-hand side symbols whose value are not used are reported.
-  For instance:
+  Typed right-hand side symbols whose values are not used are reported,
+  if the associated types have destructors.  For instance:
 
      exp: exp "?" exp ":" exp { $1 ? $1 : $3; }
        | exp "+" exp
@@ -16,14 +16,17 @@ Changes in version 2.1a:
 
   will trigger a warning about $$ and $5 in the first rule, and $3 in
   the second ($1 is copied to $$ by the default rule).  This example
-  most likely contains three errors, and should be rewritten as:
+  most likely contains three errors, and could be rewritten as:
 
-     exp: exp "?" exp ":" exp { $$ = $1 ? $3 : $5; }
-       | exp "+" exp         { $$ = $1 + $3; }
+     exp: exp "?" exp ":" exp
+           { $$ = $1 ? $3 : $5; free ($1 ? $5 : $3); free ($1); }
+       | exp "+" exp
+           { $$ = $1 ? $1 : $3; if ($1) free ($3); }
        ;
 
-  However, if the original actions were really intended, the warnings
-  can be suppressed by letting Bison believe the values are used, e.g.:
+  However, if the original actions were really intended, memory leaks
+  and all, the warnings can be suppressed by letting Bison believe the
+  values are used, e.g.:
 
      exp: exp "?" exp ":" exp { $1 ? $1 : $3; (void) ($$, $5); }
        | exp "+" exp         { $$ = $1; (void) $3; }
@@ -34,12 +37,6 @@ Changes in version 2.1a:
 
      exp: exp { push ($1); } '+' exp { push ($3); sum (); };
 
-  Mid-rule actions that use $$ cause the corresponding value to be
-  set, therefore the following action must use it.  The following rule
-  triggers a warning about $2.
-
-     exp: '1' { $$ = 1; } '+' exp { $$ = $1 + $4; };
-
   The warning is intended to help catching lost values and memory leaks.
   If a value is ignored, its associated memory typically is not reclaimed.
 
@@ -53,14 +50,14 @@ Changes in version 2.1a:
   instead of warnings.
 
 * GLR, YACC parsers.
-  The %parse-params are available in the %destructor's (and the
-  experimental %printer's) as per the documentation.
+  The %parse-params are available in the destructors (and the
+  experimental printers) as per the documentation.
 
 * Bison now warns if it finds a stray `$' or `@' in an action.
 
 * %require "VERSION"
-  To specify that the grammar file depends on features implemented in
-  Bison version VERSION or higher.
+  This specifies that the grammar file depends on features implemented
+  in Bison version VERSION or higher.
 
 * lalr1.cc: The token and value types are now class members.
   The tokens were defined as free form enums and cpp macros.  YYSTYPE
Index: tests/headers.at
===================================================================
RCS file: /cvsroot/bison/bison/tests/headers.at,v
retrieving revision 1.13
diff -p -u -r1.13 headers.at
--- tests/headers.at    6 Feb 2006 23:49:52 -0000       1.13
+++ tests/headers.at    13 Feb 2006 19:06:27 -0000
@@ -58,6 +58,8 @@ AS_MKDIR_P([$dirname])
 AT_DATA_GRAMMAR([$1.y],
 [%{
 #include <$1.h>
+void yyerror (const char *);
+int yylex (void);
 %}
 %%
 dummy:;