From 87579e03e02c7521ca3bb6ce03a0469339b9d5ce Mon Sep 17 00:00:00 2001
From: Akim Demaille <akim.demaille@gmail.com>
Date: Mon, 6 Apr 2020 18:37:51 +0200
Subject: [PATCH] skeletons: beware not to use yyarg when it's null

Reported by Adrian Vogelsgesang.

* data/skeletons/glr.c, data/skeletons/lalr1.cc,
* data/skeletons/lalr1.java, data/skeletons/yacc.c: Here.
---
 TODO                      | 3 ---
 data/skeletons/glr.c      | 4 +++-
 data/skeletons/lalr1.cc   | 3 ++-
 data/skeletons/lalr1.java | 4 +++-
 data/skeletons/yacc.c     | 4 +++-
 5 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/TODO b/TODO
index 6d5a1480..1e589ddc 100644
--- a/TODO
+++ b/TODO
@@ -1,7 +1,4 @@
 * Bison 3.6
-** syntax_error_arguments
-Don't store the lookahead if !argv.
-
 ** Documentation
 - yyexpected_tokens in all the languages.
 - YYNOMEM
diff --git a/data/skeletons/glr.c b/data/skeletons/glr.c
index f5d51bb1..c17e7208 100644
--- a/data/skeletons/glr.c
+++ b/data/skeletons/glr.c
@@ -2188,7 +2188,9 @@ yy_syntax_error_arguments (const yyGLRStack* yystackp,
   if (yytoken != YYSYMBOL_YYEMPTY)
     {
       int yyn;
-      yyarg[yycount++] = yytoken;
+      if (yyarg)
+        yyarg[yycount] = yytoken;
+      ++yycount;
       yyn = yyexpected_tokens (yystackp, yyarg ? yyarg + 1 : yyarg, yyargn - 1);
       if (yyn == YYNOMEM)
         return YYNOMEM;
diff --git a/data/skeletons/lalr1.cc b/data/skeletons/lalr1.cc
index 104009c9..7dfb63f7 100644
--- a/data/skeletons/lalr1.cc
+++ b/data/skeletons/lalr1.cc
@@ -1458,7 +1458,8 @@ b4_dollar_popdef])[]dnl
 
     if (!yyctx.lookahead ().empty ())
       {
-        yyarg[0] = yyctx.token ();
+        if (yyarg)
+          yyarg[0] = yyctx.token ();
         int yyn = yyctx.yyexpected_tokens (yyarg ? yyarg + 1 : yyarg, yyargn - 1);
         return yyn + 1;
       }
diff --git a/data/skeletons/lalr1.java b/data/skeletons/lalr1.java
index 58957a2d..529da270 100644
--- a/data/skeletons/lalr1.java
+++ b/data/skeletons/lalr1.java
@@ -981,7 +981,9 @@ b4_dollar_popdef[]dnl
     int yycount = 0;
     if (yyctx.getToken () != null)
       {
-        yyarg[yycount++] = yyctx.getToken ();
+        if (yyarg != null)
+          yyarg[yycount] = yyctx.getToken ();
+        yycount += 1;
         yycount += yyctx.getExpectedTokens (yyarg, 1, yyargn);
       }
     return yycount;
diff --git a/data/skeletons/yacc.c b/data/skeletons/yacc.c
index 99d99ff4..98612a73 100644
--- a/data/skeletons/yacc.c
+++ b/data/skeletons/yacc.c
@@ -1360,7 +1360,9 @@ yy_syntax_error_arguments (const yypcontext_t *yyctx,
     {
       int yyn;]b4_lac_if([[
       YYDPRINTF ((stderr, "Constructing syntax error message\n"));]])[
-      yyarg[yycount++] = yyctx->yytoken;
+      if (yyarg)
+        yyarg[yycount] = yyctx->yytoken;
+      ++yycount;
       yyn = yyexpected_tokens (yyctx, yyarg ? yyarg + 1 : yyarg, yyargn - 1);
       if (yyn == YYNOMEM)
         return YYNOMEM;]b4_lac_if([[