tests: use %empty

* tests/actions.at, tests/input.at, tests/reduce.at,
* tests/regression.at:
here.

tests/actions.at

@@ -261,7 +261,7 @@ AT_DATA_GRAMMAR([[input.y]],
 ]AT_YYLEX_DECLARE[
 }
 %%
-exp: /* empty */;
+exp: %empty;
 %%
 ]AT_YYERROR_DEFINE[
 ]AT_YYLEX_DEFINE[
@@ -1706,7 +1706,7 @@ AT_DATA_GRAMMAR([input.y],
 // that has set yychar might not always return normally.  Instead,
 // skeletons must translate before every use of yytoken.
 start: 'a' accept { USE($1); } ;
-accept: /*empty*/ {
+accept: %empty {
   assert (yychar == YYEMPTY);
   yychar = 'b';
   YYACCEPT;

tests/input.at

@@ -108,17 +108,17 @@ AT_SETUP([Invalid $n and @n])
 
 AT_DATA([input.y],
 [[%%
-exp: { $$ = $1 ; };
-exp: { @$ = @1 ; };
+exp: %empty { $$ = $1 ; };
+exp: %empty { @$ = @1 ; };
 ]])
 
 AT_BISON_CHECK([-fcaret input.y], [1], [],
-[[input.y:2.13-14: error: integer out of range: '$1'
- exp: { $$ = $1 ; };
-             ^^
-input.y:3.13-14: error: integer out of range: '@1'
- exp: { @$ = @1 ; };
-             ^^
+[[input.y:2.20-21: error: integer out of range: '$1'
+ exp: %empty { $$ = $1 ; };
+                    ^^
+input.y:3.20-21: error: integer out of range: '@1'
+ exp: %empty { @$ = @1 ; };
+                    ^^
 ]])
 
 AT_CLEANUP
@@ -137,7 +137,7 @@ AT_DATA([input.y],
 %%
 exp: foo { $$; } foo { $2; } foo
    | foo
-   | /* empty. */
+   | %empty
    ;
 ]])
 
@@ -154,9 +154,9 @@ input.y:5.6-32: warning: type clash on default action: <bar> != <> [-Wother]
 input.y:6.6-8: warning: type clash on default action: <bar> != <> [-Wother]
     | foo
       ^^^
-input.y:7.5: warning: empty rule for typed nonterminal, and no action [-Wother]
-    | /* empty. */
-     ^
+input.y:7.6-11: warning: empty rule for typed nonterminal, and no action [-Wother]
+    | %empty
+      ^^^^^^
 ]])
 
 AT_CLEANUP
@@ -192,7 +192,7 @@ start:
 ;
 
 a: INT | INT { } INT { } INT { };
-b: INT | /* empty */;
+b: INT | %empty;
 c: INT | INT { $]1[; } INT { $<integer>2; } INT { $<integer>4; };
 d: INT | INT { } INT { $]1[; } INT { $<integer>2; };
 e: INT | INT { } INT {  } INT { $]1[; };
@@ -220,9 +220,9 @@ input.y:11.18-20: warning: unused value: $][3 [-Wother]
 input.y:11.26-28: warning: unused value: $][5 [-Wother]
  a: INT | INT { } INT { } INT { };
                           ^^^
-input.y:12.9: warning: empty rule for typed nonterminal, and no action [-Wother]
- b: INT | /* empty */;
-         ^
+input.y:12.10-15: warning: empty rule for typed nonterminal, and no action [-Wother]
+ b: INT | %empty;
+          ^^^^^^
 ]]m4_ifval($2, [[[input.y:13.14-20: warning: unset value: $][$ [-Wmidrule-values]
  c: INT | INT { $][1; } INT { $<integer>2; } INT { $<integer>4; };
               ^^^^^^^
@@ -351,7 +351,7 @@ AT_DATA([[input.y]],
 
 %%
 
-start: ;
+start: %empty;
 
 %destructor { destroy ($$); } <*>;
 %printer { print ($$); } <*>;
@@ -453,7 +453,7 @@ AT_DATA([[input.y]],
 
 %%
 
-start: ;
+start: %empty;
 
 %destructor { destroy ($$); } <field2> <field1>;
 %printer { print ($$); } <field2> <field1>;
@@ -849,7 +849,7 @@ exp: '@<:@' '\1' two '$' '@' '{' oline output.or.oline.opt
 
 two: '\x000000000000000000000000000000000000000000000000000000000000000000002';
 oline: '@' 'o' 'l' 'i' 'n' 'e' '@' '_' '_' 'o' 'l' 'i' 'n' 'e' '_' '_';
-output.or.oline.opt: ;|oline;;|output;;;
+output.or.oline.opt: %empty;|oline;;|output;;;
 output: '#' 'o' 'u' 't' 'p' 'u' 't' ' ';
 %%
 /* Exercise M4 quoting: '@:>@@:>@', @<:@, 2.  */
@@ -931,7 +931,7 @@ m4_define([AT_CHECK_REQUIRE],
 AT_DATA_GRAMMAR([input.y],
 [[%require "$1";
 %%
-empty_file: /* empty */;
+empty_file: %empty;
 ]])
 AT_BISON_CHECK([-o input.c input.y], $2, [], ignore)
 AT_CLEANUP
@@ -1089,7 +1089,7 @@ AT_DATA([input.y],
 
 %%
 
-start: ;
+start: %empty;
 
 // Used to report a syntax error because it didn't see any kind of symbol
 // identifier.
@@ -1134,7 +1134,7 @@ AT_SETUP([%start after first rule])
 
 AT_DATA([input.y],
 [[%%
-false_start: ;
+false_start: %empty;
 start: false_start ;
 %start start;
 ]])
@@ -1155,7 +1155,7 @@ AT_SETUP([%prec takes a token])
 AT_DATA([input.y],
 [[%%
 start: PREC %prec PREC ;
-PREC: ;
+PREC: %empty;
 ]])
 
 AT_BISON_CHECK([input.y], [1], [],
@@ -1197,7 +1197,7 @@ AT_DATA([input-c.y],
 %code bad {}
 %code format {}
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[input-c.y]], [[1]], [],
 [[input-c.y:1.7: error: %code qualifier 'q' is not used
@@ -1211,7 +1211,7 @@ AT_DATA([input-c-glr.y],
 %code bad {}
  %code bad {}
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[input-c-glr.y]], [[1]], [],
 [[input-c-glr.y:1.7: error: %code qualifier 'q' is not used
@@ -1224,7 +1224,7 @@ AT_DATA([input-c++.y],
 %code bad {}
  %code q {}
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[input-c++.y]], [[1]], [],
 [[input-c++.y:1.7: error: %code qualifier 'q' is not used
@@ -1237,7 +1237,7 @@ AT_DATA([input-c++-glr.y],
 %code q {}
 %code q {}
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[input-c++-glr.y]], [[1]], [],
 [[input-c++-glr.y:1.7-9: error: %code qualifier 'bad' is not used
@@ -1250,7 +1250,7 @@ AT_DATA([special-char-@@.y],
 %code q {}
 %code q {}
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[special-char-@@.y]], [[1]], [],
 [[special-char-@@.y:1.7-9: error: %code qualifier 'bad' is not used
@@ -1263,7 +1263,7 @@ AT_DATA([special-char-@:>@.y],
 %code q {}
 %code q {}
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[special-char-@:>@.y]], [[1]], [],
 [[special-char-@:>@.y:1.7-9: error: %code qualifier 'bad' is not used
@@ -1287,7 +1287,7 @@ AT_DATA([input-redefined.y],
 %define special1 "@:>@"
 %define special2 "@<:@"
 %%
-start: ;
+start: %empty;
 ]])
 
 AT_BISON_CHECK([[input-redefined.y]], [[1]], [],
@@ -1300,7 +1300,7 @@ input-redefined.y:2.9-11:      previous definition
 AT_DATA([input-unused.y],
 [[%define var "value"
 %%
-start: ;
+start: %empty;
 ]])
 
 AT_BISON_CHECK([[input-unused.y]], [[1]], [],
@@ -1328,7 +1328,7 @@ m4@&t@_divert_pop(0)
 AT_DATA([[input.y]],
 [[%define var-dfg "gram"
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[-Dvar-dd=cmd-d1 -Dvar-dd=cmd-d2 \
                  -Fvar-ff=cmd-f1 -Fvar-ff=cmd-f2 \
@@ -1345,7 +1345,7 @@ var-fd: cmd-d
 AT_DATA([[input-dg.y]],
 [[%define var "gram"
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[-Dvar=cmd-d input-dg.y]], [[1]], [],
 [[input-dg.y:1.9-11: error: %define variable 'var' redefined
@@ -1355,7 +1355,7 @@ AT_BISON_CHECK([[-Dvar=cmd-d input-dg.y]], [[1]], [],
 AT_DATA([[input-dg.y]],
 [[%define var "gram"
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[-fcaret -Dvar=cmd-d input-dg.y]], [[1]], [],
 [[input-dg.y:1.9-11: error: %define variable 'var' redefined
@@ -1366,7 +1366,7 @@ AT_BISON_CHECK([[-fcaret -Dvar=cmd-d input-dg.y]], [[1]], [],
 
 AT_DATA([[input-unused.y]],
 [[%%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[-Dunused-d -Funused-f input-unused.y]], [[1]], [],
 [[<command line>:2: error: %define variable 'unused-d' is not used
@@ -1386,7 +1386,7 @@ AT_DATA([Input.y],
 %define public "maybe"
 %define parser_class_name "Input"
 %%
-start: ;
+start: %empty;
 ]])
 
 AT_BISON_CHECK([[Input.y]], [1], [],
@@ -1409,7 +1409,7 @@ AT_SETUP([["%define" enum variables]])
 AT_DATA([[input.y]],
 [[%define lr.default-reduction bogus
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[-fcaret input.y]], [[1]], [[]],
 [[input.y:1.9-28: error: invalid value for %define variable 'lr.default-reduction': 'bogus'
@@ -1424,7 +1424,7 @@ input.y:1.9-28:     accepted value: 'accepting'
 AT_DATA([[input.y]],
 [[%define api.push-pull neither
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[-fcaret input.y]], [[1]], [[]],
 [[input.y:1.9-21: error: invalid value for %define variable 'api.push-pull': 'neither'
@@ -1451,7 +1451,7 @@ AT_DATA([[input.y]],
 %define api.namespace "foo"
 %define variant
 %%
-start: ;
+start: %empty;
 ]])
 AT_BISON_CHECK([[-fcaret input.y]], [1], [],
 [[input.y:1.9-21: warning: deprecated directive, use '%define api.push-pull both' [-Wdeprecated]
@@ -1492,7 +1492,7 @@ AT_DATA([[input.y]],
 [[%define api.pure ]$2[
 ]$1[
 %%
-start: ;
+start: %empty;
 ]])
 
 AT_BISON_CHECK([[input.y]], [[1]], [],
@@ -1525,7 +1525,7 @@ AT_DATA([[input.y]],
 %defines
 %define api.namespace "]$1["
 %%
-start: ;
+start: %empty;
 ]])
 
 AT_BISON_CHECK([[input.y]], [1], [],
@@ -1685,7 +1685,7 @@ AT_SETUP([[LAC: Errors for %define]])
 
 AT_DATA([[input.y]],
 [[%%
-start: ;
+start: %empty;
 ]])
 
 # parse.lac.* options are useless if LAC isn't actually activated.
@@ -1708,7 +1708,7 @@ AT_SETUP([[-Werror is not affected by -Wnone and -Wall]])
 
 AT_DATA([[input.y]],
 [[%%
-foo-bar: ;
+foo-bar: %empty;
 ]])
 
 # -Werror is not enabled by -Wall or equivalent.
@@ -1745,7 +1745,7 @@ m4_pushdef([AT_TEST],
 [AT_DATA([[input.y]],
 [[$1
 %%
-exp: /* empty */;
+exp: %empty;
 ]])
 AT_BISON_CHECK([[$2 input.y]], [[1]], [[]],
 [[$3: error: '%name-prefix' and '%define api.prefix' cannot be used together

tests/reduce.at

@@ -933,7 +933,7 @@ S: 'a' A 'a'
 A: 'a' 'a' B
  ;
 B: 'a'
- | %prec 'a'
+ | %empty %prec 'a'
  ;
 c: 'a' 'a' 'b'
  | A
@@ -1533,8 +1533,8 @@ a: 'a' ;
    and multiple reductions.  The first reduction has more lookaheads than the
    second, so the first should always be preferred as the default reduction if
    enabled.  The second reduction has one lookahead.  */
-b: ;
-c: ;
+b: %empty;
+c: %empty;
 ]],
 dnl Visit each state mentioned above.
 [['a', 'a']],

tests/regression.at

@@ -373,7 +373,7 @@ AT_DATA([input.y],
 %token  <operator>  LE 134  "<="
 %left  OR  "<="
 %%
-exp: ;
+exp: %empty;
 %%
 ]])
 
@@ -721,7 +721,7 @@ AT_KEYWORDS([report])
 AT_DATA([input.y],
 [[%%
 statement:  struct_stat;
-struct_stat:  /* empty. */ | if else;
+struct_stat:  %empty | if else;
 if: "if" "const" "then" statement;
 else: "else" statement;
 %%
@@ -869,7 +869,7 @@ type: DATA
    | INVALID
    ;
 
-body: /* empty */
+body: %empty
    | body member
    ;
 
@@ -929,7 +929,7 @@ $1
 %token B
 
 %%
-program: /* empty */
+program: %empty
  | program e ';'
  | program error ';';