version 3.6

* NEWS: Record release date.

.prev-version

@@ -1 +1 @@
-3.5.92
+3.5.94

NEWS

@@ -1,39 +1,6 @@
 GNU Bison NEWS
 
-* Noteworthy changes in release 3.5.93 (2020-05-03) [beta]
-
-  Portability issues.
-
-* Noteworthy changes in release 3.5.92 (2020-05-03) [beta]
-
-  Portability issues.
-
-  More documentation.
-
-  Backward compatibility issues with C++.
-
-* Noteworthy changes in release 3.5.91 (2020-04-29) [stable]
-
-** New features
-
-*** Returning the error token
-
-  When the scanner returns an invalid token or the undefined token
-  (YYUNDEF), the parser generates an error message and enters error
-  recovery.  Because of that error message, most scanners that find lexical
-  errors generate an error message, and then ignore the invalid input
-  without entering the error-recovery.
-
-  The scanners may now return YYerror, the error token, to enter the
-  error-recovery mode without triggering an additional error message.  See
-  the bistromathic for an example.
-
-*** The bistromathic features internationalization
-
-  Its way to build the error message is more general and is easy to use in
-  other projects.
-
-* Noteworthy changes in release 3.5.90 (2020-04-18) [beta]
+* Noteworthy changes in release 3.6 (2020-05-08) [stable]
 
 ** Backward incompatible changes
 
@@ -138,6 +105,18 @@ GNU Bison NEWS
   It makes little sense to use this feature without enabling LAC (lookahead
   correction).
 
+*** Returning the error token
+
+  When the scanner returns an invalid token or the undefined token
+  (YYUNDEF), the parser generates an error message and enters error
+  recovery.  Because of that error message, most scanners that find lexical
+  errors generate an error message, and then ignore the invalid input
+  without entering the error-recovery.
+
+  The scanners may now return YYerror, the error token, to enter the
+  error-recovery mode without triggering an additional error message.  See
+  the bistromathic for an example.
+
 *** Deep overhaul of the symbol and token kinds
 
   To avoid the confusion with types in programming languages, we now refer

TODO

@@ -1,4 +1,7 @@
 * Bison 3.6
+** Doc
+*** api.header.include
+
 ** Questions
 *** Java
 - Should i18n be part of the Lexer?  Currently it's a static method of
@@ -192,10 +195,10 @@ define it to the same type as the C ptrdiff_t type.
 * Completion
 Several features are not available in all the backends.
 
-- push parsers: glr.c, glr.cc, lalr1.cc
-- lac: D, Java
-- glr: D, Java
-- token constructors: Java, C, D
+- lac: D, Java (easy)
+- push parsers: glr.c, glr.cc, lalr1.cc (not very difficult)
+- token constructors: Java, C, D (a bit difficult)
+- glr: D, Java (super difficult)
 
 * Bugs
 ** Autotest has quotation issues

data/skeletons/c.m4

@@ -205,7 +205,11 @@ m4_define([b4_c99_int_type],
 # Define private types suitable for holding small integers in C99 or later.
 m4_define([b4_c99_int_type_define],
 [m4_copy_force([b4_c99_int_type], [b4_int_type])dnl
-[/* On compilers that do not define __PTRDIFF_MAX__ etc., make sure
+[#ifdef short
+# undef short
+#endif
+
+/* On compilers that do not define __PTRDIFF_MAX__ etc., make sure
    <limits.h> and (if available) <stdint.h> are included
    so that the code can choose integer types of a good width.  */
 
@@ -261,6 +265,50 @@ typedef int yytype_uint16;
 #endif]])
 
 
+# b4_sizes_types_define
+# ---------------------
+# Define YYPTRDIFF_T/YYPTRDIFF_MAXIMUM, YYSIZE_T/YYSIZE_MAXIMUM,
+# and YYSIZEOF.
+m4_define([b4_sizes_types_define],
+[[#ifndef YYPTRDIFF_T
+# if defined __PTRDIFF_TYPE__ && defined __PTRDIFF_MAX__
+#  define YYPTRDIFF_T __PTRDIFF_TYPE__
+#  define YYPTRDIFF_MAXIMUM __PTRDIFF_MAX__
+# elif defined PTRDIFF_MAX
+#  ifndef ptrdiff_t
+#   include <stddef.h> /* INFRINGES ON USER NAME SPACE */
+#  endif
+#  define YYPTRDIFF_T ptrdiff_t
+#  define YYPTRDIFF_MAXIMUM PTRDIFF_MAX
+# else
+#  define YYPTRDIFF_T long
+#  define YYPTRDIFF_MAXIMUM LONG_MAX
+# endif
+#endif
+
+#ifndef YYSIZE_T
+# ifdef __SIZE_TYPE__
+#  define YYSIZE_T __SIZE_TYPE__
+# elif defined size_t
+#  define YYSIZE_T size_t
+# elif defined __STDC_VERSION__ && 199901 <= __STDC_VERSION__
+#  include <stddef.h> /* INFRINGES ON USER NAME SPACE */
+#  define YYSIZE_T size_t
+# else
+#  define YYSIZE_T unsigned
+# endif
+#endif
+
+#define YYSIZE_MAXIMUM                                  \
+  YY_CAST (YYPTRDIFF_T,                                 \
+           (YYPTRDIFF_MAXIMUM < YY_CAST (YYSIZE_T, -1)  \
+            ? YYPTRDIFF_MAXIMUM                         \
+            : YY_CAST (YYSIZE_T, -1)))
+
+#define YYSIZEOF(X) YY_CAST (YYPTRDIFF_T, sizeof (X))
+]])
+
+
 # b4_int_type_for(NAME)
 # ---------------------
 # Return a narrow int type able to handle numbers ranging from

data/skeletons/glr.c

@@ -249,6 +249,7 @@ static YYLTYPE yyloc_default][]b4_yyloc_default;])[
 #include <string.h>
 
 ]b4_c99_int_type_define[
+]b4_sizes_types_define[
 
 #ifndef YY_
 # if defined YYENABLE_NLS && YYENABLE_NLS
@@ -277,9 +278,6 @@ static YYLTYPE yyloc_default][]b4_yyloc_default;])[
 # define YYREALLOC realloc
 #endif
 
-#define YYSIZEMAX \
-  (PTRDIFF_MAX < SIZE_MAX ? PTRDIFF_MAX : YY_CAST (ptrdiff_t, SIZE_MAX))
-
 #ifdef __cplusplus
   typedef bool yybool;
 # define yytrue true
@@ -507,7 +505,7 @@ struct yyGLRState {
   /** Preceding state in this stack */
   yyGLRState* yypred;
   /** Source position of the last token produced by my symbol */
-  ptrdiff_t yyposn;
+  YYPTRDIFF_T yyposn;
   union {
     /** First in a chain of alternative reductions producing the
      *  nonterminal corresponding to this state, threaded through
@@ -527,8 +525,8 @@ struct yyGLRStateSet {
    *  operation, yylookaheadNeeds[0] is not maintained since it would merely
    *  duplicate yychar != ]b4_symbol(-2, id)[.  */
   yybool* yylookaheadNeeds;
-  ptrdiff_t yysize;
-  ptrdiff_t yycapacity;
+  YYPTRDIFF_T yysize;
+  YYPTRDIFF_T yycapacity;
 };
 
 struct yySemanticOption {
@@ -568,7 +566,7 @@ struct yyGLRStack {
   YYJMP_BUF yyexception_buffer;
   yyGLRStackItem* yyitems;
   yyGLRStackItem* yynextFree;
-  ptrdiff_t yyspaceLeft;
+  YYPTRDIFF_T yyspaceLeft;
   yyGLRState* yysplitPoint;
   yyGLRState* yylastDeleted;
   yyGLRStateSet yytops;
@@ -680,7 +678,7 @@ yysymbol_name (yysymbol_kind_t yysymbol)
    multiple parsers can coexist.  */
 int yydebug;
 
-static void yypstack (yyGLRStack* yystackp, ptrdiff_t yyk)
+static void yypstack (yyGLRStack* yystackp, YYPTRDIFF_T yyk)
   YY_ATTRIBUTE_UNUSED;
 static void yypdumpstack (yyGLRStack* yystackp)
   YY_ATTRIBUTE_UNUSED;
@@ -696,7 +694,7 @@ static void yypdumpstack (yyGLRStack* yystackp)
          [simple],
 [[]],
 [[#ifndef yystrlen
-# define yystrlen(S) (YY_CAST (ptrdiff_t, strlen (S)))
+# define yystrlen(S) (YY_CAST (YYPTRDIFF_T, strlen (S)))
 #endif
 
 ]b4_parse_error_bmatch(
@@ -731,12 +729,12 @@ yystpcpy (char *yydest, const char *yysrc)
    backslash-backslash).  YYSTR is taken from yytname.  If YYRES is
    null, do not copy; instead, return the length of what the result
    would have been.  */
-static ptrdiff_t
+static YYPTRDIFF_T
 yytnamerr (char *yyres, const char *yystr)
 {
   if (*yystr == '"')
     {
-      ptrdiff_t yyn = 0;
+      YYPTRDIFF_T yyn = 0;
       char const *yyp = yystr;
 
       for (;;)
@@ -1104,7 +1102,7 @@ yynewGLRStackItem (yyGLRStack* yystackp, yybool yyisState)
  *  alternative actions for YYSTATE.  Assumes that YYRHS comes from
  *  stack #YYK of *YYSTACKP. */
 static void
-yyaddDeferredAction (yyGLRStack* yystackp, ptrdiff_t yyk, yyGLRState* yystate,
+yyaddDeferredAction (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yyGLRState* yystate,
                      yyGLRState* yyrhs, yyRuleNum yyrule)
 {
   yySemanticOption* yynewOption =
@@ -1136,14 +1134,14 @@ yyinitStateSet (yyGLRStateSet* yyset)
   yyset->yycapacity = 16;
   yyset->yystates
     = YY_CAST (yyGLRState**,
-               YYMALLOC (YY_CAST (size_t, yyset->yycapacity)
+               YYMALLOC (YY_CAST (YYSIZE_T, yyset->yycapacity)
                          * sizeof yyset->yystates[0]));
   if (! yyset->yystates)
     return yyfalse;
   yyset->yystates[0] = YY_NULLPTR;
   yyset->yylookaheadNeeds
     = YY_CAST (yybool*,
-               YYMALLOC (YY_CAST (size_t, yyset->yycapacity)
+               YYMALLOC (YY_CAST (YYSIZE_T, yyset->yycapacity)
                          * sizeof yyset->yylookaheadNeeds[0]));
   if (! yyset->yylookaheadNeeds)
     {
@@ -1152,7 +1150,7 @@ yyinitStateSet (yyGLRStateSet* yyset)
     }
   memset (yyset->yylookaheadNeeds,
           0,
-          YY_CAST (size_t, yyset->yycapacity) * sizeof yyset->yylookaheadNeeds[0]);
+          YY_CAST (YYSIZE_T, yyset->yycapacity) * sizeof yyset->yylookaheadNeeds[0]);
   return yytrue;
 }
 
@@ -1165,14 +1163,14 @@ static void yyfreeStateSet (yyGLRStateSet* yyset)
 /** Initialize *YYSTACKP to a single empty stack, with total maximum
  *  capacity for all stacks of YYSIZE.  */
 static yybool
-yyinitGLRStack (yyGLRStack* yystackp, ptrdiff_t yysize)
+yyinitGLRStack (yyGLRStack* yystackp, YYPTRDIFF_T yysize)
 {
   yystackp->yyerrState = 0;
   yynerrs = 0;
   yystackp->yyspaceLeft = yysize;
   yystackp->yyitems
     = YY_CAST (yyGLRStackItem*,
-               YYMALLOC (YY_CAST (size_t, yysize)
+               YYMALLOC (YY_CAST (YYSIZE_T, yysize)
                          * sizeof yystackp->yynextFree[0]));
   if (!yystackp->yyitems)
     return yyfalse;
@@ -1198,9 +1196,9 @@ yyexpandGLRStack (yyGLRStack* yystackp)
 {
   yyGLRStackItem* yynewItems;
   yyGLRStackItem* yyp0, *yyp1;
-  ptrdiff_t yynewSize;
-  ptrdiff_t yyn;
-  ptrdiff_t yysize = yystackp->yynextFree - yystackp->yyitems;
+  YYPTRDIFF_T yynewSize;
+  YYPTRDIFF_T yyn;
+  YYPTRDIFF_T yysize = yystackp->yynextFree - yystackp->yyitems;
   if (YYMAXDEPTH - YYHEADROOM < yysize)
     yyMemoryExhausted (yystackp);
   yynewSize = 2*yysize;
@@ -1208,7 +1206,7 @@ yyexpandGLRStack (yyGLRStack* yystackp)
     yynewSize = YYMAXDEPTH;
   yynewItems
     = YY_CAST (yyGLRStackItem*,
-               YYMALLOC (YY_CAST (size_t, yynewSize)
+               YYMALLOC (YY_CAST (YYSIZE_T, yynewSize)
                          * sizeof yynewItems[0]));
   if (! yynewItems)
     yyMemoryExhausted (yystackp);
@@ -1273,7 +1271,7 @@ yyupdateSplit (yyGLRStack* yystackp, yyGLRState* yys)
 
 /** Invalidate stack #YYK in *YYSTACKP.  */
 static inline void
-yymarkStackDeleted (yyGLRStack* yystackp, ptrdiff_t yyk)
+yymarkStackDeleted (yyGLRStack* yystackp, YYPTRDIFF_T yyk)
 {
   if (yystackp->yytops.yystates[yyk] != YY_NULLPTR)
     yystackp->yylastDeleted = yystackp->yytops.yystates[yyk];
@@ -1297,7 +1295,7 @@ yyundeleteLastStack (yyGLRStack* yystackp)
 static inline void
 yyremoveDeletes (yyGLRStack* yystackp)
 {
-  ptrdiff_t yyi, yyj;
+  YYPTRDIFF_T yyi, yyj;
   yyi = yyj = 0;
   while (yyj < yystackp->yytops.yysize)
     {
@@ -1330,8 +1328,8 @@ yyremoveDeletes (yyGLRStack* yystackp)
  * state YYLRSTATE, at input position YYPOSN, with (resolved) semantic
  * value *YYVALP and source location *YYLOCP.  */
 static inline void
-yyglrShift (yyGLRStack* yystackp, ptrdiff_t yyk, yy_state_t yylrState,
-            ptrdiff_t yyposn,
+yyglrShift (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yy_state_t yylrState,
+            YYPTRDIFF_T yyposn,
             YYSTYPE* yyvalp]b4_locations_if([, YYLTYPE* yylocp])[)
 {
   yyGLRState* yynewState = &yynewGLRStackItem (yystackp, yytrue)->yystate;
@@ -1351,8 +1349,8 @@ yyglrShift (yyGLRStack* yystackp, ptrdiff_t yyk, yy_state_t yylrState,
  *  state YYLRSTATE, at input position YYPOSN, with the (unresolved)
  *  semantic value of YYRHS under the action for YYRULE.  */
 static inline void
-yyglrShiftDefer (yyGLRStack* yystackp, ptrdiff_t yyk, yy_state_t yylrState,
-                 ptrdiff_t yyposn, yyGLRState* yyrhs, yyRuleNum yyrule)
+yyglrShiftDefer (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yy_state_t yylrState,
+                 YYPTRDIFF_T yyposn, yyGLRState* yyrhs, yyRuleNum yyrule)
 {
   yyGLRState* yynewState = &yynewGLRStackItem (yystackp, yytrue)->yystate;
   YY_ASSERT (yynewState->yyisState);
@@ -1382,7 +1380,7 @@ yyglrShiftDefer (yyGLRStack* yystackp, ptrdiff_t yyk, yy_state_t yylrState,
 `----------------------------------------------------------------------*/
 
 static inline void
-yy_reduce_print (yybool yynormal, yyGLRStackItem* yyvsp, ptrdiff_t yyk,
+yy_reduce_print (yybool yynormal, yyGLRStackItem* yyvsp, YYPTRDIFF_T yyk,
                  yyRuleNum yyrule]b4_user_formals[)
 {
   int yynrhs = yyrhsLength (yyrule);]b4_locations_if([
@@ -1415,7 +1413,7 @@ yy_reduce_print (yybool yynormal, yyGLRStackItem* yyvsp, ptrdiff_t yyk,
  *  and *YYLOCP to the computed location (if any).  Return value is as
  *  for userAction.  */
 static inline YYRESULTTAG
-yydoAction (yyGLRStack* yystackp, ptrdiff_t yyk, yyRuleNum yyrule,
+yydoAction (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yyRuleNum yyrule,
             YYSTYPE* yyvalp]b4_locuser_formals[)
 {
   int yynrhs = yyrhsLength (yyrule);
@@ -1467,10 +1465,10 @@ yydoAction (yyGLRStack* yystackp, ptrdiff_t yyk, yyRuleNum yyrule,
  *  added to the options for the existing state's semantic value.
  */
 static inline YYRESULTTAG
-yyglrReduce (yyGLRStack* yystackp, ptrdiff_t yyk, yyRuleNum yyrule,
+yyglrReduce (yyGLRStack* yystackp, YYPTRDIFF_T yyk, yyRuleNum yyrule,
              yybool yyforceEval]b4_user_formals[)
 {
-  ptrdiff_t yyposn = yystackp->yytops.yystates[yyk]->yyposn;
+  YYPTRDIFF_T yyposn = yystackp->yytops.yystates[yyk]->yyposn;
 
   if (yyforceEval || yystackp->yysplitPoint == YY_NULLPTR)
     {
@@ -1492,7 +1490,7 @@ yyglrReduce (yyGLRStack* yystackp, ptrdiff_t yyk, yyRuleNum yyrule,
     }
   else
     {
-      ptrdiff_t yyi;
+      YYPTRDIFF_T yyi;
       int yyn;
       yyGLRState* yys, *yys0 = yystackp->yytops.yystates[yyk];
       yy_state_t yynewLRState;
@@ -1534,8 +1532,8 @@ yyglrReduce (yyGLRStack* yystackp, ptrdiff_t yyk, yyRuleNum yyrule,
   return yyok;
 }
 
-static ptrdiff_t
-yysplitStack (yyGLRStack* yystackp, ptrdiff_t yyk)
+static YYPTRDIFF_T
+yysplitStack (yyGLRStack* yystackp, YYPTRDIFF_T yyk)
 {
   if (yystackp->yysplitPoint == YY_NULLPTR)
     {
@@ -1544,8 +1542,8 @@ yysplitStack (yyGLRStack* yystackp, ptrdiff_t yyk)
     }
   if (yystackp->yytops.yycapacity <= yystackp->yytops.yysize)
     {
-      ptrdiff_t state_size = sizeof yystackp->yytops.yystates[0];
-      ptrdiff_t half_max_capacity = YYSIZEMAX / 2 / state_size;
+      YYPTRDIFF_T state_size = YYSIZEOF (yystackp->yytops.yystates[0]);
+      YYPTRDIFF_T half_max_capacity = YYSIZE_MAXIMUM / 2 / state_size;
       if (half_max_capacity < yystackp->yytops.yycapacity)
         yyMemoryExhausted (yystackp);
       yystackp->yytops.yycapacity *= 2;
@@ -1554,7 +1552,7 @@ yysplitStack (yyGLRStack* yystackp, ptrdiff_t yyk)
         yyGLRState** yynewStates
           = YY_CAST (yyGLRState**,
                      YYREALLOC (yystackp->yytops.yystates,
-                                (YY_CAST (size_t, yystackp->yytops.yycapacity)
+                                (YY_CAST (YYSIZE_T, yystackp->yytops.yycapacity)
                                  * sizeof yynewStates[0])));
         if (yynewStates == YY_NULLPTR)
           yyMemoryExhausted (yystackp);
@@ -1565,7 +1563,7 @@ yysplitStack (yyGLRStack* yystackp, ptrdiff_t yyk)
         yybool* yynewLookaheadNeeds
           = YY_CAST (yybool*,
                      YYREALLOC (yystackp->yytops.yylookaheadNeeds,
-                                (YY_CAST (size_t, yystackp->yytops.yycapacity)
+                                (YY_CAST (YYSIZE_T, yystackp->yytops.yycapacity)
                                  * sizeof yynewLookaheadNeeds[0])));
         if (yynewLookaheadNeeds == YY_NULLPTR)
           yyMemoryExhausted (yystackp);
@@ -1996,8 +1994,8 @@ yycompressStack (yyGLRStack* yystackp)
 }
 
 static YYRESULTTAG
-yyprocessOneStack (yyGLRStack* yystackp, ptrdiff_t yyk,
-                   ptrdiff_t yyposn]b4_pure_formals[)
+yyprocessOneStack (yyGLRStack* yystackp, YYPTRDIFF_T yyk,
+                   YYPTRDIFF_T yyposn]b4_pure_formals[)
 {
   while (yystackp->yytops.yystates[yyk] != YY_NULLPTR)
     {
@@ -2040,7 +2038,7 @@ yyprocessOneStack (yyGLRStack* yystackp, ptrdiff_t yyk,
           for (/* nothing */; *yyconflicts; yyconflicts += 1)
             {
               YYRESULTTAG yyflag;
-              ptrdiff_t yynewStack = yysplitStack (yystackp, yyk);
+              YYPTRDIFF_T yynewStack = yysplitStack (yystackp, yyk);
               YY_DPRINTF ((stderr, "Splitting off stack %ld from %ld.\n",
                            YY_CAST (long, yynewStack), YY_CAST (long, yyk)));
               yyflag = yyglrReduce (yystackp, yynewStack,
@@ -2121,6 +2119,8 @@ yypcontext_expected_tokens (const yyGLRStack* yystackp,
               yyarg[yycount++] = YY_CAST (yysymbol_kind_t, yyx);
           }
     }
+  if (yyarg && yycount == 0 && 0 < yyargn)
+    yyarg[0] = ]b4_symbol(-2, kind)[;
   return yycount;
 }]])[
 
@@ -2228,7 +2228,7 @@ yyreportSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
      one per "expected"). */
   yysymbol_kind_t yyarg[YYARGS_MAX];
   /* Cumulated lengths of YYARG.  */
-  ptrdiff_t yysize = 0;
+  YYPTRDIFF_T yysize = 0;
 
   /* Actual size of YYARG. */
   int yycount
@@ -2259,11 +2259,11 @@ yyreportSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
     int yyi;
     for (yyi = 0; yyi < yycount; ++yyi)
       {
-        ptrdiff_t yysz
+        YYPTRDIFF_T yysz
           = ]b4_parse_error_case(
                      [verbose], [[yytnamerr (YY_NULLPTR, yytname[yyarg[yyi]])]],
                      [[yystrlen (yysymbol_name (yyarg[yyi]))]]);[
-        if (YYSIZEMAX - yysize < yysz)
+        if (YYSIZE_MAXIMUM - yysize < yysz)
           yysize_overflow = yytrue;
         else
           yysize += yysz;
@@ -2271,7 +2271,7 @@ yyreportSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
   }
 
   if (!yysize_overflow)
-    yymsg = YY_CAST (char *, YYMALLOC (YY_CAST (size_t, yysize)));
+    yymsg = YY_CAST (char *, YYMALLOC (YY_CAST (YYSIZE_T, yysize)));
 
   if (yymsg)
     {
@@ -2348,7 +2348,7 @@ yyrecoverSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
 
   /* Reduce to one stack.  */
   {
-    ptrdiff_t yyk;
+    YYPTRDIFF_T yyk;
     for (yyk = 0; yyk < yystackp->yytops.yysize; yyk += 1)
       if (yystackp->yytops.yystates[yyk] != YY_NULLPTR)
         break;
@@ -2423,7 +2423,7 @@ yyparse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)
   int yyresult;
   yyGLRStack yystack;
   yyGLRStack* const yystackp = &yystack;
-  ptrdiff_t yyposn;
+  YYPTRDIFF_T yyposn;
 
   YY_DPRINTF ((stderr, "Starting parse\n"));
 
@@ -2505,7 +2505,7 @@ b4_dollar_popdef])[]dnl
       while (yytrue)
         {
           yysymbol_kind_t yytoken_to_shift;
-          ptrdiff_t yys;
+          YYPTRDIFF_T yys;
 
           for (yys = 0; yys < yystack.yytops.yysize; yys += 1)
             yystackp->yytops.yylookaheadNeeds[yys] = yychar != ]b4_symbol(-2, id)[;
@@ -2612,8 +2612,8 @@ b4_dollar_popdef])[]dnl
       yyGLRState** yystates = yystack.yytops.yystates;
       if (yystates)
         {
-          ptrdiff_t yysize = yystack.yytops.yysize;
-          ptrdiff_t yyk;
+          YYPTRDIFF_T yysize = yystack.yytops.yysize;
+          YYPTRDIFF_T yyk;
           for (yyk = 0; yyk < yysize; yyk += 1)
             if (yystates[yyk])
               {
@@ -2660,7 +2660,7 @@ yypstates (yyGLRState* yyst)
 }
 
 static void
-yypstack (yyGLRStack* yystackp, ptrdiff_t yyk)
+yypstack (yyGLRStack* yystackp, YYPTRDIFF_T yyk)
 {
   yypstates (yystackp->yytops.yystates[yyk]);
 }
@@ -2705,7 +2705,7 @@ yypdumpstack (yyGLRStack* yystackp)
 
   YY_FPRINTF ((stderr, "Tops:"));
   {
-    ptrdiff_t yyi;
+    YYPTRDIFF_T yyi;
     for (yyi = 0; yyi < yystackp->yytops.yysize; yyi += 1)
       YY_FPRINTF ((stderr, "%ld: %ld; ", YY_CAST (long, yyi),
                    YYINDEX (yystackp->yytops.yystates[yyi])));

data/skeletons/lalr1.cc

@@ -1326,6 +1326,8 @@ b4_dollar_popdef])[]dnl
             }
       }
 ]])[
+    if (yyarg && yycount == 0 && 0 < yyargn)
+      yyarg[0] = symbol_kind::]b4_symbol(-2, kind)[;
     return yycount;
   }
 

data/skeletons/lalr1.java

@@ -944,6 +944,8 @@ b4_dollar_popdef[]dnl
                   yyarg[yycount++] = SymbolKind.get (yyx);
               }
         }
+      if (yyarg != null && yycount == yyoffset && yyoffset < yyargn)
+        yyarg[yycount] = null;
       return yycount - yyoffset;
     }
   }

data/skeletons/yacc.c

@@ -403,50 +403,10 @@ m4_if(b4_api_prefix, [yy], [],
 ]b4_declare_symbol_enum[
 
 ]b4_user_post_prologue[
-]b4_percent_code_get[]dnl
-
-[#ifdef short
-# undef short
-#endif
-
+]b4_percent_code_get[
 ]b4_c99_int_type_define[
 
-#ifndef YYPTRDIFF_T
-# if defined __PTRDIFF_TYPE__ && defined __PTRDIFF_MAX__
-#  define YYPTRDIFF_T __PTRDIFF_TYPE__
-#  define YYPTRDIFF_MAXIMUM __PTRDIFF_MAX__
-# elif defined PTRDIFF_MAX
-#  ifndef ptrdiff_t
-#   include <stddef.h> /* INFRINGES ON USER NAME SPACE */
-#  endif
-#  define YYPTRDIFF_T ptrdiff_t
-#  define YYPTRDIFF_MAXIMUM PTRDIFF_MAX
-# else
-#  define YYPTRDIFF_T long
-#  define YYPTRDIFF_MAXIMUM LONG_MAX
-# endif
-#endif
-
-#ifndef YYSIZE_T
-# ifdef __SIZE_TYPE__
-#  define YYSIZE_T __SIZE_TYPE__
-# elif defined size_t
-#  define YYSIZE_T size_t
-# elif defined __STDC_VERSION__ && 199901 <= __STDC_VERSION__
-#  include <stddef.h> /* INFRINGES ON USER NAME SPACE */
-#  define YYSIZE_T size_t
-# else
-#  define YYSIZE_T unsigned
-# endif
-#endif
-
-#define YYSIZE_MAXIMUM                                  \
-  YY_CAST (YYPTRDIFF_T,                                 \
-           (YYPTRDIFF_MAXIMUM < YY_CAST (YYSIZE_T, -1)  \
-            ? YYPTRDIFF_MAXIMUM                         \
-            : YY_CAST (YYSIZE_T, -1)))
-
-#define YYSIZEOF(X) YY_CAST (YYPTRDIFF_T, sizeof (X))
+]b4_sizes_types_define[
 
 /* Stored state numbers (used for stacks). */
 typedef ]b4_int_type(0, m4_eval(b4_states_number - 1))[ yy_state_t;
@@ -1198,6 +1158,8 @@ yypcontext_expected_tokens (const yypcontext_t *yyctx,
               yyarg[yycount++] = YY_CAST (yysymbol_kind_t, yyx);
           }
     }]])[
+  if (yyarg && yycount == 0 && 0 < yyargn)
+    yyarg[0] = ]b4_symbol(-2, kind)[;
   return yycount;
 }
 

doc/bison.texi

@@ -300,10 +300,7 @@ Bison Declarations
 Parser C-Language Interface
 
 * Parser Function::         How to call @code{yyparse} and what it returns.
-* Push Parser Function::    How to call @code{yypush_parse} and what it returns.
-* Pull Parser Function::    How to call @code{yypull_parse} and what it returns.
-* Parser Create Function::  How to call @code{yypstate_new} and what it returns.
-* Parser Delete Function::  How to call @code{yypstate_delete} and what it returns.
+* Push Parser Interface::   How to create, use, and destroy push parsers.
 * Lexical::                 You must supply a function @code{yylex}
                               which reads tokens.
 * Error Reporting::         Passing error messages to the user.
@@ -6927,10 +6924,7 @@ in the grammar file, you are likely to run into trouble.
 
 @menu
 * Parser Function::         How to call @code{yyparse} and what it returns.
-* Push Parser Function::    How to call @code{yypush_parse} and what it returns.
-* Pull Parser Function::    How to call @code{yypull_parse} and what it returns.
-* Parser Create Function::  How to call @code{yypstate_new} and what it returns.
-* Parser Delete Function::  How to call @code{yypstate_delete} and what it returns.
+* Push Parser Interface::   How to create, use, and destroy push parsers.
 * Lexical::                 You must supply a function @code{yylex}
                               which reads tokens.
 * Error Reporting::         Passing error messages to the user.
@@ -7033,16 +7027,40 @@ void yyerror (YYLTYPE *llocp, int *randomness, const char *msg);
 int  yyparse (int *randomness);
 @end example
 
-@node Push Parser Function
-@section The Push Parser Function @code{yypush_parse}
-@findex yypush_parse
+@node Push Parser Interface
+@section Push Parser Interface
 
-You call the function @code{yypush_parse} to parse a single token.  This
+@findex yypstate_new
+You call the function @code{yypstate_new} to create a new parser instance.
+This function is available if either the @samp{%define api.push-pull push}
+or @samp{%define api.push-pull both} declaration is used.  @xref{Push Decl}.
+
+@deftypefun {yypstate*} yypstate_new (@code{void})
+@anchor{yypstate_new}
+Return a valid parser instance if there is memory available, 0 otherwise.
+In impure mode, it will also return 0 if a parser instance is currently
+allocated.
+@end deftypefun
+
+@findex yypstate_delete
+You call the function @code{yypstate_delete} to delete a parser instance.
 function is available if either the @samp{%define api.push-pull push} or
 @samp{%define api.push-pull both} declaration is used.
 @xref{Push Decl}.
 
+@deftypefun void yypstate_delete (@code{yypstate *}@var{yyps})
+@anchor{yypstate_delete}
+Reclaim the memory associated with a parser instance.  After this call, you
+should no longer attempt to use the parser instance.
+@end deftypefun
+
+@findex yypush_parse
+You call the function @code{yypush_parse} to parse a single token.  This
+function is available if either the @samp{%define api.push-pull push} or
+@samp{%define api.push-pull both} declaration is used.  @xref{Push Decl}.
+
 @deftypefun int yypush_parse (@code{yypstate *}@var{yyps})
+@anchor{yypush_parse}
 The value returned by @code{yypush_parse} is the same as for @code{yyparse}
 with the following exception: it returns @code{YYPUSH_MORE} if more input is
 required to finish parsing the grammar.
@@ -7056,50 +7074,35 @@ reuse.  For example, a calculator application which parses each input line
 as an expression can just keep reusing the same @code{yyps} even if an input
 was invalid.
 
-@node Pull Parser Function
-@section The Pull Parser Function @code{yypull_parse}
-@findex yypull_parse
-
 You call the function @code{yypull_parse} to parse the rest of the input
 stream.  This function is available if the @samp{%define api.push-pull both}
-declaration is used.
-@xref{Push Decl}.
+declaration is used.  @xref{Push Decl}.
 
 @deftypefun int yypull_parse (@code{yypstate *}@var{yyps})
+@anchor{yypull_parse}
 The value returned by @code{yypull_parse} is the same as for @code{yyparse}.
 
 The parser instance @code{yyps} may be reused for new parses.
 @end deftypefun
 
-@node Parser Create Function
-@section The Parser Create Function @code{yystate_new}
-@findex yypstate_new
+@deftypefun int yypstate_expected_tokens (@code{const yypstate *}yyps, @code{yysymbol_kind_t} @var{argv}@code{[]}, @code{int} @var{argc})
+Fill @var{argv} with the expected tokens, which never includes
+@code{YYSYMBOL_YYEMPTY}, @code{YYSYMBOL_YYerror}, or
+@code{YYSYMBOL_YYUNDEF}.
 
-You call the function @code{yypstate_new} to create a new parser instance.
-This function is available if either the @samp{%define api.push-pull push} or
-@samp{%define api.push-pull both} declaration is used.
-@xref{Push Decl}.
+Never put more than @var{argc} elements into @var{argv}, and on success
+return the number of tokens stored in @var{argv}.  If there are more
+expected tokens than @var{argc}, fill @var{argv} up to @var{argc} and return
+0.  If there are no expected tokens, also return 0, but set @code{argv[0]}
+to @code{YYSYMBOL_YYEMPTY}.
 
-@deftypefun {yypstate*} yypstate_new (@code{void})
-The function will return a valid parser instance if there was memory available
-or 0 if no memory was available.
-In impure mode, it will also return 0 if a parser instance is currently
-allocated.
+When LAC is enabled, may return a negative number on errors,
+such as @code{YYENOMEM} on memory exhaustion.
+
+If @var{argv} is null, return the size needed to store all the possible
+values, which is always less than @code{YYNTOKENS}.
 @end deftypefun
 
-@node Parser Delete Function
-@section The Parser Delete Function @code{yystate_delete}
-@findex yypstate_delete
-
-You call the function @code{yypstate_delete} to delete a parser instance.
-function is available if either the @samp{%define api.push-pull push} or
-@samp{%define api.push-pull both} declaration is used.
-@xref{Push Decl}.
-
-@deftypefun void yypstate_delete (@code{yypstate *}@var{yyps})
-This function will reclaim the memory associated with a parser instance.
-After this call, you should no longer attempt to use the parser instance.
-@end deftypefun
 
 @node Lexical
 @section The Lexical Analyzer Function @code{yylex}
@@ -7551,9 +7554,12 @@ Fill @var{argv} with the expected tokens, which never includes
 @code{YYSYMBOL_YYUNDEF}.
 
 Never put more than @var{argc} elements into @var{argv}, and on success
-return the effective number of tokens stored in @var{argv}.  Return 0 if
-there are more than @var{argc} expected tokens, yet fill @var{argv} up to
-@var{argc}.  When LAC is enabled, may return a negative number on errors,
+return the number of tokens stored in @var{argv}.  If there are more
+expected tokens than @var{argc}, fill @var{argv} up to @var{argc} and return
+0.  If there are no expected tokens, also return 0, but set @code{argv[0]}
+to @code{YYSYMBOL_YYEMPTY}.
+
+When LAC is enabled, may return a negative number on errors,
 such as @code{YYENOMEM} on memory exhaustion.
 
 If @var{argv} is null, return the size needed to store all the possible
@@ -7660,11 +7666,11 @@ recovery.
 In either case, the rest of the action is not executed.
 @end deffn
 
-@deffn {Macro} YYEMPTY
+@deffn {Value} YYEMPTY
 Value stored in @code{yychar} when there is no lookahead token.
 @end deffn
 
-@deffn {Macro} YYEOF
+@deffn {Value} YYEOF
 Value stored in @code{yychar} when the lookahead is the end of the input
 stream.
 @end deffn
@@ -12137,9 +12143,10 @@ Fill @var{argv} with the expected tokens, which never includes
 @code{symbol_kind::S_YYUNDEF}.
 
 Never put more than @var{argc} elements into @var{argv}, and on success
-return the effective number of tokens stored in @var{argv}.  Return 0 if
-there are more than @var{argc} expected tokens, yet fill @var{argv} up to
-@var{argc}.
+return the number of tokens stored in @var{argv}.  If there are more
+expected tokens than @var{argc}, fill @var{argv} up to @var{argc} and return
+0.  If there are no expected tokens, also return 0, but set @code{argv[0]}
+to @code{symbol_kind::S_YYEMPTY}.
 
 If @var{argv} is null, return the size needed to store all the possible
 values, which is always less than @code{YYNTOKENS}.
@@ -13298,9 +13305,10 @@ Fill @var{argv} with the expected tokens, which never includes
 @code{SymbolKind.S_YYERROR}, or @code{SymbolKind.S_YYUNDEF}.
 
 Never put more than @var{argc} elements into @var{argv}, and on success
-return the effective number of tokens stored in @var{argv}.  Return 0 if
-there are more than @var{argc} expected tokens, yet fill @var{argv} up to
-@var{argc}.
+return the number of tokens stored in @var{argv}.  If there are more
+expected tokens than @var{argc}, fill @var{argv} up to @var{argc} and return
+0.  If there are no expected tokens, also return 0, but set @code{argv[0]}
+to @code{null}.
 
 If @var{argv} is null, return the size needed to store all the possible
 values, which is always less than @code{YYNTOKENS}.
@@ -14692,6 +14700,14 @@ is given a nonzero value, the parser will output information on input
 symbols and parser action.  @xref{Tracing}.
 @end deffn
 
+@deffn {Value} YYEMPTY
+The pseudo token kind when there is no lookahead token.
+@end deffn
+
+@deffn {Value} YYEOF
+The token kind denoting is the end of the input stream.
+@end deffn
+
 @deffn {Macro} yyerrok
 Macro to cause parser to recover immediately to its normal mode
 after a syntax error.  @xref{Error Recovery}.
@@ -14781,24 +14797,26 @@ Deprecated, use @code{%printer} instead (@pxref{Printer Decl}).
 @deffn {Function} yypstate_delete
 The function to delete a parser instance, produced by Bison in push mode;
 call this function to delete the memory associated with a parser.
-@xref{Parser Delete Function}.  Does nothing when called with a null pointer.
+@xref{yypstate_delete,,@code{yypstate_delete}}.  Does nothing when called
+with a null pointer.
 @end deffn
 
 @deffn {Function} yypstate_new
 The function to create a parser instance, produced by Bison in push mode;
 call this function to create a new parser.
-@xref{Parser Create Function}.
+@xref{yypstate_new,,@code{yypstate_new}}.
 @end deffn
 
 @deffn {Function} yypull_parse
 The parser function produced by Bison in push mode; call this function to
 parse the rest of the input stream.
-@xref{Pull Parser Function}.
+@xref{yypull_parse,,@code{yypull_parse}}.
 @end deffn
 
 @deffn {Function} yypush_parse
 The parser function produced by Bison in push mode; call this function to
-parse a single token.  @xref{Push Parser Function}.
+parse a single token.
+@xref{yypush_parse,,@code{yypush_parse}}.
 @end deffn
 
 @deffn {Macro} YYRECOVERING
@@ -14846,6 +14864,10 @@ should not be confused with the @emph{symbol kinds}, used internally by the
 parser.
 @end deffn
 
+@deffn {Value} YYUNDEF
+The token kind denoting an unknown token.
+@end deffn
+
 
 @node Glossary
 @appendix Glossary
@@ -14932,12 +14954,21 @@ A continuous flow of data between devices or programs.
 @item Kind
 ``Token'' and ``symbol'' are each overloaded to mean either a grammar symbol
 (kind) or all parse info (kind, value, location) associated with occurrences
-of that grammar symbol from the input.  To disambiguate, we use ``token
-kind'' and ``symbol kind'' to mean both grammar symbols and the types that
-represent them in a base programming language (C, C++, etc.). However, we
-use ``token'' and ``symbol'' without the word ``kind'' to mean parsed
+of that grammar symbol from the input.  To disambiguate,
+
+@itemize
+@item
+we use ``token kind'' and ``symbol kind'' to mean both grammar symbols and
+the values that represent them in a base programming language (C, C++,
+etc.).  The names of the types of these values are typically
+@code{token_kind_t}, or @code{token_kind_type}, or @code{TokenKind},
+depending on the programming language.
+
+@item
+we use ``token'' and ``symbol'' without the word ``kind'' to mean parsed
 occurrences, and we append the word ``type'' to refer to the types that
 represent them in a base programming language.
+@end itemize
 
 In summary: When you see ``kind'', interpret ``symbol'' or ``token'' to mean
 a @emph{grammar symbol}.  When you don't see ``kind'' (including when you

doc/local.mk

@@ -131,7 +131,7 @@ dist_man_MANS = $(top_srcdir)/%D%/bison.1
 EXTRA_DIST += $(dist_man_MANS:.1=.x)
 MAINTAINERCLEANFILES += $(dist_man_MANS)
 
-# Differences to ignore when comparing the man page (the date).
+# Differences to ignore when comparing man pages (the date).
 remove_time_stamp = \
   sed 's/^\(\.TH[^"]*"[^"]*"[^"]*\)"[^"]*"/\1/'
 
@@ -140,17 +140,31 @@ if ! CROSS_COMPILING
 MAN_DEPS = %D%/bison.help %D%/bison.x $(top_srcdir)/configure
 endif
 
+# If we don't have help2man, just touch the target.  Maintainers must
+# have the real thing, so if there's a .git directory, fail hard.
+#
+# We shouldn't need this, but on some OS the timestamps in the tarball
+# leave us no choice.  See
+# https://lists.gnu.org/r/bug-bison/2020-05/msg00055.html.
 $(top_srcdir)/%D%/bison.1: $(MAN_DEPS)
-	$(AM_V_GEN)$(HELP2MAN)			\
-	    --include=$(top_srcdir)/%D%/bison.x	\
-	    --output=$@.tmp tests/bison
-	$(AM_V_at)if $(remove_time_stamp) $@ >$@a.tmp 2>/dev/null &&		\
-	   $(remove_time_stamp) $@.tmp | cmp $@a.tmp - >/dev/null 2>&1; then	\
-	  touch $@;								\
-	else									\
-	  mv $@.tmp $@;								\
+	$(AM_V_GEN)if $(HELP2MAN) --version >/dev/null 2>&1; then	\
+	  $(HELP2MAN)							\
+	    --include=$(top_srcdir)/%D%/bison.x				\
+	    --output=$@.tmp tests/bison &&				\
+	  { $(remove_time_stamp) $@     >$@a.tmp || true; } &&		\
+	    $(remove_time_stamp) $@.tmp >$@b.tmp &&			\
+	  if diff $@a.tmp $@b.tmp >/dev/null 2>&1; then			\
+	    touch $@;							\
+	  else								\
+	    mv $@.tmp $@;						\
+	  fi &&								\
+	  rm -f $@*.tmp;						\
+	elif test -d $(srcdir)/.git; then				\
+	  echo >&2 "ERROR: $@: help2man is needed";			\
+	  exit 1;							\
+	else								\
+	  touch $@;							\
 	fi
-	$(AM_V_at)rm -f $@*.tmp
 
 if ENABLE_YACC
 nodist_man_MANS = %D%/yacc.1

examples/c/bistromathic/bistromathic.test

@@ -41,13 +41,14 @@ echo >perfect '> 0
 echo >ok '0'
 echo '0' | prog >effective
 
-if diff perfect effective >/dev/null 2>&1; then
+echo "checking for readline output"
+if diff perfect effective; then
     # Alles ist gut.
-elif diff ok effective >/dev/null 2>&1; then
+    strip_prompt=false
+elif diff ok effective; then
     strip_prompt=true
 else
-    echo "SKIP: this is not the GNU Readline we expect"
-    exit 77
+    skip "this is not the GNU Readline we expect"
 fi
 
 
@@ -96,7 +97,7 @@ cat >input <<EOF
 EOF
 run 0 '> *
 > ''
-err: 1.1: syntax error: expected end of file or - or ( or exit or number or function or variable before *'
+err: 1.1: syntax error: expected end of file or - or ( or exit or number or function etc., before *'
 
 cat >input <<EOF
 1 + 2 * * 3
@@ -257,14 +258,22 @@ err: Cleanup: popping nterm input (1.1-4: )' -p
 # From now on, the differences between versions of GNU Readline are
 # too painful to try to cope with.
 if $strip_prompt; then
-    echo "SKIP: this is not the GNU Readline we expect"
-    if $exit; then
-        exit 0
-    else
-        exit 1
-    fi
+  echo "SKIP: this is not the GNU Readline we expect"
+  exit $status
 fi
 
+# On Windows10/MSYS2 the ^G coming from <tab> completion is not
+# emitted the same way
+# (https://lists.gnu.org/r/bug-bison/2020-05/msg00076.html).
+echo "checking for kernel name"
+case `uname -s` in
+  (MSYS*)
+    echo "SKIP: this is Windows/MSYS"
+    exit $status
+    ;;
+esac
+
+
 # Check completion after an operator.
 sed -e 's/\\t/	/g' >input <<EOF
 (1+\t\t

examples/c/bistromathic/parse.y

@@ -333,7 +333,7 @@ error_format_string (int argc)
     case 5: return _("%@: syntax error: expected %0e or %1e or %2e or %3e before %u");
     case 6: return _("%@: syntax error: expected %0e or %1e or %2e or %3e or %4e before %u");
     case 7: return _("%@: syntax error: expected %0e or %1e or %2e or %3e or %4e or %5e before %u");
-    case 8: return _("%@: syntax error: expected %0e or %1e or %2e or %3e or %4e or %5e or %6e before %u");
+    case 8: return _("%@: syntax error: expected %0e or %1e or %2e or %3e or %4e or %5e etc., before %u");
     }
 }
 
@@ -341,12 +341,15 @@ error_format_string (int argc)
 int
 yyreport_syntax_error (const yypcontext_t *ctx)
 {
-  enum { ARGS_MAX = 7 };
+  enum { ARGS_MAX = 6 };
   yysymbol_kind_t arg[ARGS_MAX];
   int argsize = yypcontext_expected_tokens (ctx, arg, ARGS_MAX);
   if (argsize < 0)
     return argsize;
-  const char *format = error_format_string (1 + argsize);
+  const int too_many_expected_tokens = argsize == 0 && arg[0] != YYSYMBOL_YYEMPTY;
+  if (too_many_expected_tokens)
+    argsize = ARGS_MAX;
+  const char *format = error_format_string (1 + argsize + too_many_expected_tokens);
 
   while (*format)
     // %@: location.
@@ -400,7 +403,9 @@ void yyerror (YYLTYPE *loc, char const *format, ...)
 static char *
 xstrndup (const char *string, size_t n)
 {
-  size_t len = strnlen (string, n);
+  // len = strnlen (string, n), portably.
+  const char *end = memchr (string, '\0', n);
+  size_t len = end ? (size_t) (end - string) : n;
   char *new = malloc (len + 1);
   assert (new);
   new[len] = '\0';

examples/c/reccalc/reccalc.test

@@ -15,7 +15,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-(seq 0) >/dev/null 2>&1 || exit 77
+(seq 0) >/dev/null 2>&1 || skip "gimme one seq"
 
 cat >input <<EOF
 1+2*3

examples/test

@@ -25,7 +25,7 @@ medir=$(dirname "$1" | sed -e 's,.*examples/,,')
 number=1
 
 # Exit status of this script.
-exit=true
+status=0
 
 # top_builddir.
 cwd=$(pwd)
@@ -34,6 +34,13 @@ cwd=$(pwd)
 # See bistromathic.test.
 strip_prompt=false
 
+# If diff supports --strip-trailing-cr, use it, to avoid EOL issues
+# when testing Java programs on Windows.
+echo "checking for diff --strip-trailing-cr"
+if diff --strip-trailing-cr "$1" "$1"; then
+  diff_opts=--strip-trailing-cr
+fi
+
 # The exercised program.
 abs_medir=$cwd/examples/$medir
 if test -x "$abs_medir/$me"; then
@@ -68,6 +75,20 @@ trap cleanup 0 1 2 13 15
 mkdir $$.dir
 cd $$.dir
 
+
+# skip [MSG]
+# ----------
+# Skip this test.
+skip ()
+{
+  if test x"$1" != x; then
+    echo "SKIP: $1"
+  fi
+  # See Autoconf's doc on 'trap'.
+  (exit 77); exit 77
+}
+
+
 # run [-noerr, -n] EXPECTED-EXIT-STATUS EXPECTED-OUTPUT [PARSER-OPTIONS]
 # ----------------------------------------------------------------------
 # -noerr: ignore stderr, otherwise merge it into effective output.
@@ -115,7 +136,7 @@ run ()
   } >eff
 
   if test $sta_eff -eq $sta_exp; then
-    if diff eff exp >/dev/null 2>&1; then
+    if diff $diff_opts eff exp >/dev/null 2>&1; then
       echo "$me: PASS: $number"
     else
       echo "$me: FAIL: $number"
@@ -126,21 +147,21 @@ run ()
       echo "$me: effective output:"
       sed -e 's/^/  /' eff
       echo "$me: diff:"
-      diff -u exp eff | sed -e 's/^/  /'
-      exit=false
+      diff $diff_opts -u exp eff | sed -e 's/^/  /'
+      status=1
     fi
   else
     echo "$me: FAIL: $number (expected status: $sta_exp, effective: $sta_eff)"
     cat err_eff
-    exit=false
+    status=1
   fi
   number=$(expr $number + 1)
 }
 
 # We have cd'd one level deeper.
 case $1 in
-  /*) . "$1";;
-  *)  . "../$1";;
+  /*) . "$1" || status=2;;
+  *)  . "../$1" || status=2;;
 esac
 
-$exit
+exit $status

src/parse-gram.c

@@ -1,4 +1,4 @@
-/* A Bison parser, made by GNU Bison 3.5.91.  */
+/* A Bison parser, made by GNU Bison 3.6.  */
 
 /* Bison implementation for Yacc-like parsers in C
 
@@ -49,7 +49,7 @@
 #define YYBISON 1
 
 /* Bison version.  */
-#define YYBISON_VERSION "3.5.91"
+#define YYBISON_VERSION "3.6"
 
 /* Skeleton name.  */
 #define YYSKELETON_NAME "yacc.c"
@@ -408,6 +408,7 @@ typedef int yytype_uint16;
 
 #define YYSIZEOF(X) YY_CAST (YYPTRDIFF_T, sizeof (X))
 
+
 /* Stored state numbers (used for stacks). */
 typedef yytype_uint8 yy_state_t;
 
@@ -1631,6 +1632,8 @@ yypcontext_expected_tokens (const yypcontext_t *yyctx,
               yyarg[yycount++] = yysym;
           }
     }
+  if (yyarg && yycount == 0 && 0 < yyargn)
+    yyarg[0] = YYSYMBOL_YYEMPTY;
   return yycount;
 }
 

src/parse-gram.h

@@ -1,4 +1,4 @@
-/* A Bison parser, made by GNU Bison 3.5.91.  */
+/* A Bison parser, made by GNU Bison 3.6.  */
 
 /* Bison interface for Yacc-like parsers in C
 

tests/atlocal.in

@@ -144,3 +144,44 @@ export LC_CTYPE
 
 # Empty if no xsltproc was found
 : ${XSLTPROC='@XSLTPROC@'}
+
+
+# Some tests expect a precise diff format.  See AT_DIFF_U_CHECK.
+# See https://lists.gnu.org/r/bug-bison/2020-05/msg00049.html.
+cat >conftest.1 <<EOF
+1
+2
+3
+4
+5
+6
+EOF
+
+cat >conftest.2 <<EOF
+1
+22
+3
+4
+55
+6
+EOF
+
+cat >conftest.expected <<EOF
+@@ -1,6 +1,6 @@
+ 1
+-2
++22
+ 3
+ 4
+-5
++55
+ 6
+EOF
+
+diff -u conftest.1 conftest.2 2>/dev/null | sed -n '/^@@/,$p' | sed 's/^ $//' >conftest.diff
+if diff conftest.expected conftest.diff >/dev/null; then
+    DIFF_U_WORKS=true
+else
+    DIFF_U_WORKS=false
+fi
+rm conftest.*

tests/diagnostics.at

@@ -265,7 +265,8 @@ input.y: <warning>warning:</warning> fix-its can be applied.  Rerun with option
 ]])
 
 
-# Likewise, but currently not portable to Cygwin.
+# Likewise, but currently not portable to AIX and Cygwin.
+# https://lists.gnu.org/r/bug-bison/2020-05/msg00050.html
 # https://lists.gnu.org/r/bug-bison/2020-05/msg00003.html.
 AT_TEST([[Tabulations and multibyte characters]],
 [[%%
@@ -277,7 +278,7 @@ e: {∇⃗×𝐸⃗ = -∂𝐵⃗/∂t}
       |    <warning>^~~~~~~~~~~~~~</warning>
       |    <fixit-insert>%empty</fixit-insert>
 input.y: <warning>warning:</warning> fix-its can be applied.  Rerun with option '--update'. [<warning>-Wother</warning>]
-]], [], [uname -a | grep -i cygwin])
+]], [], [uname -a | $EGREP -i 'aix|cygwin'])
 
 
 ## --------------- ##

tests/existing.at

@@ -35,14 +35,9 @@ dnl time comes, just use sed to drop the line numbers.  For now, as LR(1)
 dnl support is rapidly evolving, let's keep that information to be careful.
 dnl However, we don't do diffs for canonical LR(1) because the diff is huge.
 m4_pushdef([AT_LALR1_DIFF_CHECK],
-[dnl We need diff -u, which is not portable.
-AT_CHECK([diff -u /dev/null /dev/null || exit 77], [0], [ignore])
-
-AT_CHECK([[sed 's/^%define lr.type .*$//' input.y > input-lalr.y]])
+[AT_CHECK([[sed 's/^%define lr.type .*$//' input.y > input-lalr.y]])
 AT_BISON_CHECK([[--report=all input-lalr.y]], [[0]], [ignore], [ignore])
-AT_CHECK([[diff -u input-lalr.output input.output \
-           | sed -n '/^@@/,$p' | sed 's/^ $//']],
-         [[0]], [$1])])
+AT_DIFF_U_CHECK([[input-lalr.output input.output]], [$1])])
 
 AT_TEST_TABLES_AND_PARSE([$2[: LALR(1)]], [[LALR]], [[last-state]],
                          [[%define lr.type lalr

tests/local.at

@@ -83,6 +83,16 @@ set x `LC_ALL=C ls -l '$1'` &&
 ## ------------- ##
 
 
+# AT_DIFF_U_CHECK(DIFF-ARGS, EXPECTED-DIFF)
+# -----------------------------------------
+# If diff -u works as we expect, use it, with headers stripped.
+m4_define([AT_DIFF_U_CHECK],
+[if $DIFF_U_WORKS; then
+  AT_CHECK([diff -u $1 | sed -n '/^@@/,$p' | sed 's/^ $//'], [0], [$2])
+fi
+])
+
+
 # AT_PERL_CHECK(PERL-ARGS, ...)
 # -----------------------------
 # If Perl is available, run this test.