parsers: rename YY_NULL as YY_NULLPTR to avoid conflicts with Flex

Flex also defines YY_NULL (to 0).  Avoid gratuitous conflicts.

* data/c.m4 (b4_null_define): Rename YY_NULL as YY_NULLPTR.

* data/glr.c, data/lalr1.cc, data/location.cc, data/variant.hh,
* data/yacc.c, src/parse-gram.c, tests/actions.at, tests/c++.at,
* tests/cxx-type.at, tests/glr-regression.at, tests/headers.at,
* tests/push.at, tests/regression.at:
Adjust.

tests/actions.at

@@ -596,7 +596,7 @@ thing:
 ;
 %%
 /* Alias to ARGV[1]. */
-const char *source = YY_NULL;
+const char *source = YY_NULLPTR;
 
 ]AT_YYERROR_DEFINE[
 

tests/c++.at

@@ -796,11 +796,11 @@ item:
 // Not just 'E', otherwise we reduce when 'E' is the lookahead, and
 // then the stack is emptied, defeating the point of the test.
 | 'E' 'a' { YYUSE($][1); $][$ = $][2; }
-| 'R'     { ]AT_VARIANT_IF([], [$][$ = YY_NULL; delete $][1]; )[YYERROR; }
+| 'R'     { ]AT_VARIANT_IF([], [$][$ = YY_NULLPTR; delete $][1]; )[YYERROR; }
 | 'p'     { $][$ = $][1; }
 | 's'     { $][$ = $][1; throw std::runtime_error ("reduction"); }
-| 'T'     { ]AT_VARIANT_IF([], [$][$ = YY_NULL; delete $][1]; )[YYABORT; }
-| error   { ]AT_VARIANT_IF([], [$][$ = YY_NULL; ])[yyerrok; }
+| 'T'     { ]AT_VARIANT_IF([], [$][$ = YY_NULLPTR; delete $][1]; )[YYABORT; }
+| error   { ]AT_VARIANT_IF([], [$][$ = YY_NULLPTR; ])[yyerrok; }
 ;
 %%
 
@@ -868,7 +868,7 @@ main (int argc, const char *argv[])
   {
     std::cerr << "unknown exception caught" << std::endl;
   }
-  Object::log (YY_NULL, "end");
+  Object::log (YY_NULLPTR, "end");
   assert (Object::empty());
   return res;
 }

tests/cxx-type.at

@@ -94,19 +94,19 @@ prog :
 
 stmt : expr ';'  $2     { $$ = ]$[1; }
      | decl      $3
-     | error ';'        { $$ = new_nterm ("<error>", YY_NULL, YY_NULL, YY_NULL); }
+     | error ';'        { $$ = new_nterm ("<error>", YY_NULLPTR, YY_NULLPTR, YY_NULLPTR); }
      | '@'              { YYACCEPT; }
      ;
 
 expr : ID
      | TYPENAME '(' expr ')'
-                        { $$ = new_nterm ("<cast>(%s,%s)", ]$[3, ]$[1, YY_NULL); }
-     | expr '+' expr    { $$ = new_nterm ("+(%s,%s)", ]$[1, ]$[3, YY_NULL); }
-     | expr '=' expr    { $$ = new_nterm ("=(%s,%s)", ]$[1, ]$[3, YY_NULL); }
+                        { $$ = new_nterm ("<cast>(%s,%s)", ]$[3, ]$[1, YY_NULLPTR); }
+     | expr '+' expr    { $$ = new_nterm ("+(%s,%s)", ]$[1, ]$[3, YY_NULLPTR); }
+     | expr '=' expr    { $$ = new_nterm ("=(%s,%s)", ]$[1, ]$[3, YY_NULLPTR); }
      ;
 
 decl : TYPENAME declarator ';'
-                        { $$ = new_nterm ("<declare>(%s,%s)", ]$[1, ]$[2, YY_NULL); }
+                        { $$ = new_nterm ("<declare>(%s,%s)", ]$[1, ]$[2, YY_NULLPTR); }
      | TYPENAME declarator '=' expr ';'
                         { $$ = new_nterm ("<init-declare>(%s,%s,%s)", ]$[1,
                                           ]$[2, ]$[4); }
@@ -195,7 +195,7 @@ main (int argc, char **argv)
               {
                 colNum += 1;
                 tok = c;
-                yylval = YY_NULL;
+                yylval = YY_NULLPTR;
               }]AT_LOCATION_IF([[
             yylloc.last_column = colNum-1;]])[
             return tok;
@@ -287,7 +287,7 @@ m4_bmatch([$2], [stmtMerge],
 [[static YYSTYPE
 stmtMerge (YYSTYPE x0, YYSTYPE x1)
 {
-  return new_nterm ("<OR>(%s,%s)", x0, x1, YY_NULL);
+  return new_nterm ("<OR>(%s,%s)", x0, x1, YY_NULLPTR);
 }
 ]])
 )

tests/glr-regression.at

@@ -67,7 +67,7 @@ static YYSTYPE exprMerge (YYSTYPE x0, YYSTYPE x1)
   return 0;
 }
 
-const char *input = YY_NULL;
+const char *input = YY_NULLPTR;
 
 int
 main (int argc, const char* argv[])
@@ -304,7 +304,7 @@ MergeRule (int x0, int x1)
 }
 ]AT_YYERROR_DEFINE[
 
-FILE *input = YY_NULL;
+FILE *input = YY_NULLPTR;
 
 int P[] = { P1, P2 };
 int O[] = { O1, O2 };

tests/headers.at

@@ -229,7 +229,7 @@ AT_CHECK([[$PERL -n -0777 -e '
       |YY_IGNORE_MAYBE_UNINITIALIZED_(?:BEGIN|END)
       |YY_INITIAL_VALUE
       |YY_\w+_INCLUDED
-      |YY_NULL
+      |YY_NULLPTR
       |(defined|if)\ YYDEBUG
       )\b}{}gx;
   while (/^(.*YY.*)$/gm)

tests/push.at

@@ -57,12 +57,12 @@ main (void)
   /* yypstate_delete used to leak ps->yyss if the stack was reallocated but the
      parse did not return on success, syntax error, or memory exhaustion.  */
   ps = yypstate_new ();
-  assert (yypush_parse (ps, 'a', YY_NULL) == YYPUSH_MORE);
+  assert (yypush_parse (ps, 'a', YY_NULLPTR) == YYPUSH_MORE);
   yypstate_delete (ps);
 
   ps = yypstate_new ();
-  assert (yypush_parse (ps, 'a', YY_NULL) == YYPUSH_MORE);
-  assert (yypush_parse (ps, 'b', YY_NULL) == YYPUSH_MORE);
+  assert (yypush_parse (ps, 'a', YY_NULLPTR) == YYPUSH_MORE);
+  assert (yypush_parse (ps, 'b', YY_NULLPTR) == YYPUSH_MORE);
   yypstate_delete (ps);
 
   return 0;
@@ -111,11 +111,11 @@ main (void)
     {
       yypstate *ps = yypstate_new ();
       assert (ps);
-      assert (yypstate_new () == YY_NULL);
+      assert (yypstate_new () == YY_NULLPTR);
       ]m4_if([$1], [[both]], [[assert (yyparse () == 2)]])[;
       yychar = 0;
       assert (yypush_parse (ps) == 0);
-      assert (yypstate_new () == YY_NULL);
+      assert (yypstate_new () == YY_NULLPTR);
       ]m4_if([$1], [[both]], [[assert (yyparse () == 2)]])[;
       yypstate_delete (ps);
     }

tests/regression.at

@@ -770,7 +770,7 @@ static const yytype_uint8 yyrline[] =
 static const char *const yytname[] =
 {
   "$end", "error", "$undefined", "\"if\"", "\"const\"", "\"then\"",
-  "\"else\"", "$accept", "statement", "struct_stat", "if", "else", YY_NULL
+  "\"else\"", "$accept", "statement", "struct_stat", "if", "else", YY_NULLPTR
 };
 static const yytype_uint16 yytoknum[] =
 {