Re: c: use YYNOMEM instead of -2

[Akim Demaille]

> Le 28 mars 2020 à 18:18, Akim Demaille <address@hidden> a écrit :
> 
> I'm almost done with the deprecation of yysyntax_error_arguments, but in the 
> course, I found other things to do.  It seems Bison 3.6 is not in sight yet, 
> but I'm quite happy with the changes it will bring.
> 
> First, some TODO

Then some done.  I took YYNOMEM for similarity with errno's ENOMEM, but if 
people have better suggestions, I'd be happy to hear them.

commit 59d820d1ef6312da0cf08c27c5ac9c9fec4b87ab
Author: Akim Demaille <address@hidden>
Date:   Fri Mar 27 06:33:08 2020 +0100

    c: use YYNOMEM instead of -2
    
    See 84b1972c96060866b4bd94a33b97711f8f7d0b6c.
    
    * data/skeletons/glr.c, data/skeletons/yacc.c (YYNOMEM): New.
    Use it.

diff --git a/TODO b/TODO
index fff82ea5..3d45888f 100644
--- a/TODO
+++ b/TODO
@@ -2,13 +2,12 @@
 ** Documentation
 - yyexpected_tokens in all the languages.
 - remove yysyntax_error_arguments.
+- YYNOMEM
 
 ** Naming conventions
 yysyntax_error_arguments should be yy_syntax_error_arguments, since it's a
 private implementation detail.
 
-Give a name to magic constants such as -2 (YYNOMEM?).
-
 There's no good reason to use the "yy" prefix in parser::context, is there?
 See also the case of Java.  We should keep the prefix for private
 implementation details, but maybe not for public APIs.
diff --git a/data/skeletons/glr.c b/data/skeletons/glr.c
index 4aa8bf0e..bf8e1522 100644
--- a/data/skeletons/glr.c
+++ b/data/skeletons/glr.c
@@ -430,6 +430,8 @@ YYLTYPE yylloc;]])[
 int yynerrs;
 int yychar;])[
 
+enum { YYNOMEM = -2 };
+
 static const int YYEOF = 0;
 static const int YYEMPTY = -2;
 
@@ -2186,8 +2188,8 @@ yysyntax_error_arguments (const yyGLRStack* yystackp,
       int yyn;
       yyarg[yycount++] = yytoken;
       yyn = yyexpected_tokens (yystackp, yyarg ? yyarg + 1 : yyarg, yyargn - 
1);
-      if (yyn == -2)
-        return -2;
+      if (yyn == YYNOMEM)
+        return YYNOMEM;
       else
         yycount += yyn;
     }
@@ -2222,7 +2224,7 @@ yyreportSyntaxError (yyGLRStack* 
yystackp]b4_user_formals[)
   /* Actual size of YYARG. */
   int yycount
     = yysyntax_error_arguments (yystackp, yyarg, YYARGS_MAX);
-  if (yycount == -2)
+  if (yycount == YYNOMEM)
     yyMemoryExhausted (yystackp);
 
   switch (yycount)
diff --git a/data/skeletons/yacc.c b/data/skeletons/yacc.c
index 9b79f0d9..0bf65601 100644
--- a/data/skeletons/yacc.c
+++ b/data/skeletons/yacc.c
@@ -706,6 +706,8 @@ static const ]b4_int_type_for([b4_toknum])[ yytoknum[] =
 
 ]b4_parser_tables_define[
 
+enum { YYNOMEM = -2 };
+
 #define yyerrok         (yyerrstatus = 0)
 #define yyclearin       (yychar = YYEMPTY)
 #define YYEMPTY         (-2)
@@ -877,7 +879,7 @@ static char yypstate_allocated = 0;]])])[
    *YYTOP, and *YYCAPACITY to reflect the new capacity and memory
    location.  If *YYBOTTOM != YYBOTTOM_NO_FREE, then free the old stack
    using YYSTACK_FREE.  Return 0 if successful or if no reallocation is
-   required.  Return -2 if memory is exhausted.  */
+   required.  Return YYNOMEM if memory is exhausted.  */
 static int
 yy_lac_stack_realloc (YYPTRDIFF_T *yycapacity, YYPTRDIFF_T yyadd,
 #if ]b4_api_PREFIX[DEBUG
@@ -902,7 +904,7 @@ yy_lac_stack_realloc (YYPTRDIFF_T *yycapacity, YYPTRDIFF_T 
yyadd,
         {
           YYDPRINTF ((stderr, "%smax size exceeded%s", yydebug_prefix,
                       yydebug_suffix));
-          return -2;
+          return YYNOMEM;
         }
       if (YYMAXDEPTH < yyalloc)
         yyalloc = YYMAXDEPTH;
@@ -914,7 +916,7 @@ yy_lac_stack_realloc (YYPTRDIFF_T *yycapacity, YYPTRDIFF_T 
yyadd,
         {
           YYDPRINTF ((stderr, "%srealloc failed%s", yydebug_prefix,
                       yydebug_suffix));
-          return -2;
+          return YYNOMEM;
         }
       if (*yytop != yytop_empty)
         {
@@ -970,7 +972,7 @@ do {                                                        
            \
       yy_lac_established = 1;                                           \
       switch (yy_lac (yyesa, &yyes, &yyes_capacity, yyssp, yytoken))    \
         {                                                               \
-        case -2:                                                        \
+        case YYNOMEM:                                                   \
           goto yyexhaustedlab;                                          \
         case 1:                                                         \
           goto yyerrlab;                                                \
@@ -1005,7 +1007,7 @@ do {                                                      
               \
 
 /* Given the stack whose top is *YYSSP, return 0 iff YYTOKEN can
    eventually (after perhaps some reductions) be shifted, return 1 if
-   not, or return -2 if memory is exhausted.  As preconditions and
+   not, or return YYNOMEM if memory is exhausted.  As preconditions and
    postconditions: *YYES_CAPACITY is the allocated size of the array to
    which *YYES points, and either *YYES = YYESA or *YYES points to an
    array allocated with YYSTACK_ALLOC.  yy_lac may overwrite the
@@ -1105,7 +1107,7 @@ yy_lac (yy_state_t *yyesa, yy_state_t **yyes,
                                       yyes, yyesa, &yyesp, yyes_prev))
               {
                 YYDPRINTF ((stderr, "\n"));
-                return -2;
+                return YYNOMEM;
               }
             YY_IGNORE_USELESS_CAST_BEGIN
             *++yyesp = YY_CAST (yy_state_t, yystate);
@@ -1132,9 +1134,9 @@ typedef struct
 /* Put in YYARG at most YYARGN of the expected tokens given the
    current YYCTX, and return the number of tokens stored in YYARG.  If
    YYARG is null, return the number of expected tokens (guaranteed to
-   be less than YYNTOKENS).  Return -2 on memory exhaustion.  Return 0
-   if there are more than YYARGN expected tokens, yet fill YYARG up to
-   YYARGN. */]b4_push_if([[
+   be less than YYNTOKENS).  Return YYNOMEM on memory exhaustion.
+   Return 0 if there are more than YYARGN expected tokens, yet fill
+   YYARG up to YYARGN. */]b4_push_if([[
 static int
 yypstate_expected_tokens (yypstate *yyps,
                           int yyarg[], int yyargn)]], [[
@@ -1151,8 +1153,8 @@ yyexpected_tokens (const yyparse_context_t *yyctx,
       switch (yy_lac (]b4_push_if([[yyps->yyesa, &yyps->yyes, 
&yyps->yyes_capacity, yyps->yyssp, yyx]],
                                   [[yyctx->yyesa, yyctx->yyes, 
yyctx->yyes_capacity, yyctx->yyssp, yyx]])[))
         {
-        case -2:
-          return -2;
+        case YYNOMEM:
+          return YYNOMEM;
         case 1:
           continue;
         default:
@@ -1354,8 +1356,8 @@ yysyntax_error_arguments (const yyparse_context_t *yyctx,
       YYDPRINTF ((stderr, "Constructing syntax error message\n"));]])[
       yyarg[yycount++] = yyctx->yytoken;
       yyn = yyexpected_tokens (yyctx, yyarg ? yyarg + 1 : yyarg, yyargn - 1);
-      if (yyn == -2)
-        return -2;]b4_lac_if([[
+      if (yyn == YYNOMEM)
+        return YYNOMEM;]b4_lac_if([[
       else if (yyn == 0)
         YYDPRINTF ((stderr, "No expected tokens.\n"));]])[
       else
@@ -1371,9 +1373,9 @@ yysyntax_error_arguments (const yyparse_context_t *yyctx,
 
    Return 0 if *YYMSG was successfully written.  Return -1 if *YYMSG is
    not large enough to hold the message.  In that case, also set
-   *YYMSG_ALLOC to the required number of bytes.  Return -2 if the
+   *YYMSG_ALLOC to the required number of bytes.  Return YYNOMEM if the
    required number of bytes is too large to store]b4_lac_if([[ or if
-   yy_lac returned -2]])[.  */
+   yy_lac returned YYNOMEM]])[.  */
 static int
 yysyntax_error (YYPTRDIFF_T *yymsg_alloc, char **yymsg,
                 const yyparse_context_t *yyctx)
@@ -1389,8 +1391,8 @@ yysyntax_error (YYPTRDIFF_T *yymsg_alloc, char **yymsg,
 
   /* Actual size of YYARG. */
   int yycount = yysyntax_error_arguments (yyctx, yyarg, YYARGS_MAX);
-  if (yycount == -2)
-    return -2;
+  if (yycount == YYNOMEM)
+    return YYNOMEM;
 
   switch (yycount)
     {
@@ -1422,7 +1424,7 @@ yysyntax_error (YYPTRDIFF_T *yymsg_alloc, char **yymsg,
         if (yysize <= yysize1 && yysize1 <= YYSTACK_ALLOC_MAXIMUM)
           yysize = yysize1;
         else
-          return -2;
+          return YYNOMEM;
       }
   }
 
@@ -1933,11 +1935,11 @@ yyerrlab:
               {
                 yymsg = yymsgbuf;
                 yymsg_alloc = sizeof yymsgbuf;
-                yysyntax_error_status = -2;
+                yysyntax_error_status = YYNOMEM;
               }
           }
         yyerror (]b4_yyerror_args[yymsgp);
-        if (yysyntax_error_status == -2)
+        if (yysyntax_error_status == YYNOMEM)
           goto yyexhaustedlab;
       }]])[
     }