YYFAIL: warn about uses and remove from lalr1.java.

* NEWS (2.5): Document.
* data/lalr1.java (parser::YYStack::YYFAIL): Rename to YYERRLAB,
and make it private.  Update all uses.
* src/scan-code.l (SC_RULE_ACTION): Implement warning.
(cherry picked from commit 4395a9ff4fd518580b9abe9482783e8eba192f34)

Conflicts:

	data/lalr1.java

diff --git a/ChangeLog b/ChangeLog
index d36938cd95728ca81f696b496992a19677141ca1..312796a4921439537b7c44e771283fbf5815167e 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2009-12-21  Joel E. Denny  <jdenny@clemson.edu>
+
+       YYFAIL: warn about uses and remove from lalr1.java.
+       * NEWS (2.5): Document.
+       * data/lalr1.java (parser::YYStack::YYFAIL): Rename to YYERRLAB,
+       and make it private.  Update all uses.
+       * src/scan-code.l (SC_RULE_ACTION): Implement warning.
+
 2009-12-21  Joel E. Denny  <jdenny@clemson.edu>
 
        YYFAIL: deprecate.

diff --git a/NEWS b/NEWS
index 492aa87672ce6d1aec4c1db521d01f2deab57d9c..d6eed9123bb0e27eaac991e6ab5d642d54a4e494 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -119,6 +119,17 @@ Bison News
   POSIX Yacc whose use is reported by -Wyacc, and rejected in Yacc
   mode (--yacc).
 
+** YYFAIL now produces warnings and Java parsers no longer implement it.
+
+  YYFAIL has existed for many years as an undocumented feature of
+  deterministic parsers in C generated by Bison.  More recently, it was
+  a documented feature of Bison's experimental Java parsers.  As
+  promised in Bison 2.4.2's NEWS entry, any appearance of YYFAIL in a
+  semantic action now produces a deprecation warning, and Java parsers
+  no longer implement YYFAIL at all.  For further details, including a
+  discussion of how to suppress C preprocessor warnings about YYFAIL
+  being unused, see the Bison 2.4.2 NEWS entry.
+
 ** Temporary hack for adding a semicolon to the user action.
 
   Previously, Bison appended a semicolon to every user action for

diff --git a/data/lalr1.java b/data/lalr1.java
index 0ba03125a2c0326b0dd173d8d0531cb4f7e932a4..25bb1bdbd55af538e91bf3230d597300b2731285 100644 (file)
--- a/data/lalr1.java
+++ b/data/lalr1.java
@@ -308,12 +308,9 @@ b4_lexer_if([[
    * printing an error message.  */
   public static final int YYERROR = 2;
 
-  /**
-   * Returned by a Bison action in order to print an error message and start
-   * error recovery.  Formally deprecated in Bison 2.4.2's NEWS entry, where
-   * a plan to phase it out is discussed.  */
-  public static final int YYFAIL = 3;
-
+  // Internal return codes that are not supported for user semantic
+  // actions.
+  private static final int YYERRLAB = 3;
   private static final int YYNEWSTATE = 4;
   private static final int YYDEFAULT = 5;
   private static final int YYREDUCE = 6;
@@ -530,7 +527,7 @@ m4_popdef([b4_at_dollar])])dnl
         else if ((yyn = yytable_[yyn]) <= 0)
           {
            if (yy_table_value_is_error_ (yyn))
-             label = YYFAIL;
+             label = YYERRLAB;
            else
              {
                yyn = -yyn;
@@ -564,7 +561,7 @@ m4_popdef([b4_at_dollar])])dnl
       case YYDEFAULT:
         yyn = yydefact_[yystate];
         if (yyn == 0)
-          label = YYFAIL;
+          label = YYERRLAB;
         else
           label = YYREDUCE;
         break;
@@ -581,7 +578,7 @@ m4_popdef([b4_at_dollar])])dnl
       /*------------------------------------.
       | yyerrlab -- here on detecting error |
       `------------------------------------*/
-      case YYFAIL:
+      case YYERRLAB:
         /* If not already recovering from an error, report this error.  */
         if (yyerrstatus_ == 0)
           {

diff --git a/src/scan-code.l b/src/scan-code.l
index a84b4c1fcc96afd7f8a8a2ee28d581e44a1c41db..e2eb76a732a6873e63da8e7d08152ea5b416adb3 100644 (file)
--- a/src/scan-code.l
+++ b/src/scan-code.l
@@ -245,7 +245,20 @@ ref      -?[0-9]+|{id}|"["{id}"]"|"$"
   {splice}  STRING_GROW;
   [\n\r]    STRING_GROW; if (in_cpp) in_cpp = need_semicolon = false; 
   [ \t\f]   STRING_GROW;
-  .         STRING_GROW; need_semicolon = true;
+
+  /* YYFAIL is undocumented and was formally deprecated in Bison
+     2.4.2.  */
+  YYFAIL {
+    STRING_GROW; need_semicolon = true;
+    warn_at (*loc, _("use of YYFAIL, which is deprecated and will be"
+                     " removed"));
+  }
+
+  /* The sole purpose of this is to make sure identifiers that merely
+     contain YYFAIL don't produce the above warning.  */
+  [A-Za-z_][0-9A-Za-z_]* STRING_GROW; need_semicolon = true;
+
+  . STRING_GROW; need_semicolon = true;
 }
 
 <SC_SYMBOL_ACTION>