X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/83b66dddb649f9bc5331970c0a1ef82396715e86..d140056923f4942c645cf56e0f6940e28113cfdd:/tests/conflicts.at?ds=sidebyside

diff --git a/tests/conflicts.at b/tests/conflicts.at
index 2647c8d2..169509f2 100644
--- a/tests/conflicts.at
+++ b/tests/conflicts.at
@@ -1,7 +1,6 @@
 # Exercising Bison on conflicts.                         -*- Autotest -*-
 
-# Copyright (C) 2002, 2003, 2004, 2005, 2007, 2009 Free Software
-# Foundation, Inc.
+# Copyright (C) 2002-2005, 2007-2012 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -38,7 +37,7 @@ e: 'e' | /* Nothing. */;
 ]])
 
 AT_BISON_CHECK([-o input.c input.y], 0, [],
-[[input.y:4.9: warning: rule useless in parser due to conflicts: e: /* empty */
+[[input.y:4.9: warning: rule useless in parser due to conflicts: e: /* empty */ [-Wother]
 ]])
 
 AT_CLEANUP
@@ -50,20 +49,17 @@ AT_CLEANUP
 
 AT_SETUP([%nonassoc and eof])
 
+AT_BISON_OPTION_PUSHDEFS
 AT_DATA_GRAMMAR([input.y],
 [[
 %{
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <assert.h>
 
 #define YYERROR_VERBOSE 1
-static void
-yyerror (const char *msg)
-{
-  fprintf (stderr, "%s\n", msg);
-}
-
+]AT_YYERROR_DEFINE[
 /* The current argument. */
 static const char *input;
 
@@ -71,8 +67,7 @@ static int
 yylex (void)
 {
   static size_t toknum;
-  if (! (toknum <= strlen (input)))
-    abort ();
+  assert (toknum <= strlen (input));
   return input[toknum++];
 }
 
@@ -93,32 +88,445 @@ main (int argc, const char *argv[])
   return yyparse ();
 }
 ]])
+AT_BISON_OPTION_POPDEFS
 
-# Specify the output files to avoid problems on different file systems.
-AT_BISON_CHECK([-o input.c input.y])
+m4_pushdef([AT_NONASSOC_AND_EOF_CHECK],
+[AT_BISON_CHECK([$1[ -o input.c input.y]])
 AT_COMPILE([input])
 
+m4_pushdef([AT_EXPECTING], [m4_if($2, [correct], [[, expecting $end]])])
+
 AT_PARSER_CHECK([./input '0<0'])
-# FIXME: This is an actual bug, but a new one, in the sense that
-# no one has ever spotted it!  The messages are *wrong*: there should
-# be nothing there, it should be expected eof.
 AT_PARSER_CHECK([./input '0<0<0'], [1], [],
-         [syntax error, unexpected '<', expecting '<' or '>'
+         [syntax error, unexpected '<'AT_EXPECTING
 ])
 
 AT_PARSER_CHECK([./input '0>0'])
 AT_PARSER_CHECK([./input '0>0>0'], [1], [],
-         [syntax error, unexpected '>', expecting '<' or '>'
+         [syntax error, unexpected '>'AT_EXPECTING
 ])
 
 AT_PARSER_CHECK([./input '0<0>0'], [1], [],
-         [syntax error, unexpected '>', expecting '<' or '>'
+         [syntax error, unexpected '>'AT_EXPECTING
+])
+
+m4_popdef([AT_EXPECTING])])
+
+# Expected token list is missing.
+AT_NONASSOC_AND_EOF_CHECK([], [[incorrect]])
+
+# We must disable default reductions in inconsistent states in order to
+# have an explicit list of all expected tokens.
+AT_NONASSOC_AND_EOF_CHECK([[-Dlr.default-reductions=consistent]],
+                          [[correct]])
+
+# lr.default-reductions=consistent happens to work for this test case.
+# However, for other grammars, lookahead sets can be merged for
+# different left contexts, so it is still possible to have an incorrect
+# expected list.  Canonical LR is almost a general solution (that is, it
+# can fail only when %nonassoc is used), so make sure it gives the same
+# result as above.
+AT_NONASSOC_AND_EOF_CHECK([[-Dlr.type=canonical-lr]], [[correct]])
+
+# parse.lac=full is a completely general solution that does not require
+# any of the above sacrifices.  Of course, it does not extend the
+# language-recognition power of LALR to (IE)LR, but it does ensure that
+# the reported list of expected tokens matches what the given parser
+# would have accepted in place of the unexpected token.
+AT_NONASSOC_AND_EOF_CHECK([[-Dparse.lac=full]], [[correct]])
+
+m4_popdef([AT_NONASSOC_AND_EOF_CHECK])
+
+AT_CLEANUP
+
+
+
+## ------------------------------------------- ##
+## parse.error=verbose and consistent errors.  ##
+## ------------------------------------------- ##
+
+AT_SETUP([[parse.error=verbose and consistent errors]])
+
+m4_pushdef([AT_CONSISTENT_ERRORS_CHECK], [
+
+AT_BISON_OPTION_PUSHDEFS([$1])
+
+m4_pushdef([AT_YYLEX_PROTOTYPE],
+[AT_SKEL_CC_IF([[int yylex (yy::parser::semantic_type *lvalp)]],
+               [[int yylex (YYSTYPE *lvalp)]])])
+
+AT_SKEL_JAVA_IF([AT_DATA], [AT_DATA_GRAMMAR])([input.y],
+[AT_SKEL_JAVA_IF([[
+
+%code imports {
+  import java.io.IOException;
+}]], [[
+
+%code {]AT_SKEL_CC_IF([[
+  #include <string>]], [[
+  #include <assert.h>
+  #include <stdio.h>
+  ]AT_YYERROR_DECLARE])[
+  ]AT_YYLEX_PROTOTYPE[;
+  #define USE(Var)
+}
+
+]AT_SKEL_CC_IF([[%defines]], [[%define api.pure]])])[
+
+]$1[
+
+%define parse.error verbose
+
+%%
+
+]$2[
+
+]AT_SKEL_JAVA_IF([[%code lexer {]], [[%%]])[
+
+/*--------.
+| yylex.  |
+`--------*/]AT_SKEL_JAVA_IF([[
+
+public String input = "]$3[";
+public int index = 0;
+public int yylex ()
+{
+  if (index < input.length ())
+    return input.charAt (index++);
+  else
+    return 0;
+}
+public Object getLVal ()
+{
+  return new Integer(1);
+}]], [[
+
+]AT_YYLEX_PROTOTYPE[
+{
+  static char const *input = "]$3[";
+  *lvalp = 1;
+  return *input++;
+}]])[
+]AT_YYERROR_DEFINE[
+]AT_SKEL_JAVA_IF([[
+};
+
+%%]])[
+
+/*-------.
+| main.  |
+`-------*/]AT_SKEL_JAVA_IF([[
+
+class input
+{
+  public static void main (String args[]) throws IOException
+  {
+    YYParser p = new YYParser ();
+    p.parse ();
+  }
+}]], [AT_SKEL_CC_IF([[
+
+int
+main (void)
+{
+  yy::parser parser;
+  return parser.parse ();
+}]], [[
+
+int
+main (void)
+{
+  return yyparse ();
+}]])])[
+]])
+
+AT_FULL_COMPILE([[input]])
+
+m4_pushdef([AT_EXPECTING], [m4_if($5, [ab], [[, expecting 'a' or 'b']],
+                                  $5, [a],  [[, expecting 'a']],
+                                  $5, [b],  [[, expecting 'b']])])
+
+AT_SKEL_JAVA_IF([AT_JAVA_PARSER_CHECK([[input]], [[0]]],
+                [AT_PARSER_CHECK([[./input]], [[1]]]),
+[[]],
+[[syntax error, unexpected ]$4[]AT_EXPECTING[
+]])
+
+m4_popdef([AT_EXPECTING])
+m4_popdef([AT_YYLEX_PROTOTYPE])
+AT_BISON_OPTION_POPDEFS
+
 ])
 
+m4_pushdef([AT_PREVIOUS_STATE_GRAMMAR],
+[[%nonassoc 'a';
+
+start: consistent-error-on-a-a 'a' ;
+
+consistent-error-on-a-a:
+    'a' default-reduction
+  | 'a' default-reduction 'a'
+  | 'a' shift
+  ;
+
+default-reduction: /*empty*/ ;
+shift: 'b' ;
+
+// Provide another context in which all rules are useful so that this
+// test case looks a little more realistic.
+start: 'b' consistent-error-on-a-a 'c' ;
+]])
+
+m4_pushdef([AT_PREVIOUS_STATE_INPUT], [[a]])
+
+# Unfortunately, no expected tokens are reported even though 'b' can be
+# accepted.  Nevertheless, the main point of this test is to make sure
+# that at least the unexpected token is reported.  In a previous version
+# of Bison, it wasn't reported because the error is detected in a
+# consistent state with an error action, and that case always triggered
+# the simple "syntax error" message.
+#
+# The point isn't to test IELR here, but state merging happens to
+# complicate this example.
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[none]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr
+                             %glr-parser]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[none]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr
+                             %language "c++"]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[none]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr
+                             %language "java"]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[end of input]], [[none]])
+
+# Even canonical LR doesn't foresee the error for 'a'!
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr
+                             %define lr.default-reductions consistent]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[ab]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr
+                             %define lr.default-reductions accepting]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[ab]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type canonical-lr]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[ab]])
+
+# Only LAC gets it right.
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type canonical-lr
+                             %define parse.lac full]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[b]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type ielr
+                             %define parse.lac full]],
+                           [AT_PREVIOUS_STATE_GRAMMAR],
+                           [AT_PREVIOUS_STATE_INPUT],
+                           [[$end]], [[b]])
+
+m4_popdef([AT_PREVIOUS_STATE_GRAMMAR])
+m4_popdef([AT_PREVIOUS_STATE_INPUT])
+
+m4_pushdef([AT_USER_ACTION_GRAMMAR],
+[[%nonassoc 'a';
+
+// If $$ = 0 here, then we know that the 'a' destructor is being invoked
+// incorrectly for the 'b' set in the semantic action below.  All 'a'
+// tokens are returned by yylex, which sets $$ = 1.
+%destructor {
+  if (!$$)
+    fprintf (stderr, "Wrong destructor.\n");
+} 'a';
+
+// Rather than depend on an inconsistent state to induce reading a
+// lookahead as in the previous grammar, just assign the lookahead in a
+// semantic action.  That lookahead isn't needed before either error
+// action is encountered.  In a previous version of Bison, this was a
+// problem as it meant yychar was not translated into yytoken before
+// either error action.  The second error action thus invoked a
+// destructor that it selected according to the incorrect yytoken.  The
+// first error action would have reported an incorrect unexpected token
+// except that, due to the bug described in the previous grammar, the
+// unexpected token was not reported at all.
+start: error-reduce consistent-error 'a' { USE ($][3); } ;
+
+error-reduce:
+  'a' 'a' consistent-reduction consistent-error 'a'
+  { USE (($][1, $][2, $][5)); }
+| 'a' error
+  { USE ($][1); }
+;
+
+consistent-reduction: /*empty*/ {
+  assert (yychar == YYEMPTY);
+  yylval = 0;
+  yychar = 'b';
+} ;
+
+consistent-error:
+  'a' { USE ($][1); }
+| /*empty*/ %prec 'a'
+;
+
+// Provide another context in which all rules are useful so that this
+// test case looks a little more realistic.
+start: 'b' consistent-error 'b' ;
+]])
+m4_pushdef([AT_USER_ACTION_INPUT], [[aa]])
+
+AT_CONSISTENT_ERRORS_CHECK([[]],
+                           [AT_USER_ACTION_GRAMMAR],
+                           [AT_USER_ACTION_INPUT],
+                           [['b']], [[none]])
+AT_CONSISTENT_ERRORS_CHECK([[%glr-parser]],
+                           [AT_USER_ACTION_GRAMMAR],
+                           [AT_USER_ACTION_INPUT],
+                           [['b']], [[none]])
+# No C++ or Java test because yychar cannot be manipulated by users.
+
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.default-reductions consistent]],
+                           [AT_USER_ACTION_GRAMMAR],
+                           [AT_USER_ACTION_INPUT],
+                           [['b']], [[none]])
+
+# Canonical LR doesn't foresee the error for 'a'!
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.default-reductions accepting]],
+                           [AT_USER_ACTION_GRAMMAR],
+                           [AT_USER_ACTION_INPUT],
+                           [[$end]], [[a]])
+AT_CONSISTENT_ERRORS_CHECK([[%define lr.type canonical-lr]],
+                           [AT_USER_ACTION_GRAMMAR],
+                           [AT_USER_ACTION_INPUT],
+                           [[$end]], [[a]])
+
+AT_CONSISTENT_ERRORS_CHECK([[%define parse.lac full]],
+                           [AT_USER_ACTION_GRAMMAR],
+                           [AT_USER_ACTION_INPUT],
+                           [['b']], [[none]])
+AT_CONSISTENT_ERRORS_CHECK([[%define parse.lac full
+                             %define lr.default-reductions accepting]],
+                           [AT_USER_ACTION_GRAMMAR],
+                           [AT_USER_ACTION_INPUT],
+                           [[$end]], [[none]])
+
+m4_popdef([AT_USER_ACTION_GRAMMAR])
+m4_popdef([AT_USER_ACTION_INPUT])
+
+m4_popdef([AT_CONSISTENT_ERRORS_CHECK])
+
 AT_CLEANUP
 
 
 
+## ------------------------------------------------------- ##
+## LAC: %nonassoc requires splitting canonical LR states.  ##
+## ------------------------------------------------------- ##
+
+# This test case demonstrates that, when %nonassoc is used, canonical
+# LR(1) parser table construction followed by conflict resolution
+# without further state splitting is not always sufficient to produce a
+# parser that can detect all syntax errors as soon as possible on one
+# token of lookahead.  However, LAC solves the problem completely even
+# with minimal LR parser tables.
+
+AT_SETUP([[LAC: %nonassoc requires splitting canonical LR states]])
+AT_BISON_OPTION_PUSHDEFS
+AT_DATA_GRAMMAR([[input.y]],
+[[%code {
+  #include <stdio.h>
+  ]AT_YYERROR_DECLARE[
+  ]AT_YYLEX_DECLARE[
+}
+
+%error-verbose
+%nonassoc 'a'
+
+%%
+
+start:
+  'a' problem 'a' // First context.
+| 'b' problem 'b' // Second context.
+| 'c' reduce-nonassoc // Just makes reduce-nonassoc useful.
+;
+
+problem:
+  look reduce-nonassoc
+| look 'a'
+| look 'b'
+;
+
+// For the state reached after shifting the 'a' in these productions,
+// lookahead sets are the same in both the first and second contexts.
+// Thus, canonical LR reuses the same state for both contexts.  However,
+// the lookahead 'a' for the reduction "look: 'a'" later becomes an
+// error action only in the first context.  In order to immediately
+// detect the syntax error on 'a' here for only the first context, this
+// canonical LR state would have to be split into two states, and the
+// 'a' lookahead would have to be removed from only one of the states.
+look:
+  'a' // Reduction lookahead set is always ['a', 'b'].
+| 'a' 'b'
+| 'a' 'c' // 'c' is forgotten as an expected token.
+;
+
+reduce-nonassoc: %prec 'a';
+
+%%
+]AT_YYERROR_DEFINE[
+]AT_YYLEX_DEFINE(["aaa"])[
+
+int
+main (void)
+{
+  return yyparse ();
+}
+]])
+AT_BISON_OPTION_POPDEFS
+
+# Show canonical LR's failure.
+AT_BISON_CHECK([[-Dlr.type=canonical-lr -o input.c input.y]],
+               [[0]], [[]],
+[[input.y: conflicts: 2 shift/reduce
+]])
+AT_COMPILE([[input]])
+AT_PARSER_CHECK([[./input]], [[1]], [[]],
+[[syntax error, unexpected 'a', expecting 'b'
+]])
+
+# It's corrected by LAC.
+AT_BISON_CHECK([[-Dlr.type=canonical-lr -Dparse.lac=full \
+                 -o input.c input.y]], [[0]], [[]],
+[[input.y: conflicts: 2 shift/reduce
+]])
+AT_COMPILE([[input]])
+AT_PARSER_CHECK([[./input]], [[1]], [[]],
+[[syntax error, unexpected 'a', expecting 'b' or 'c'
+]])
+
+# IELR is sufficient when LAC is used.
+AT_BISON_CHECK([[-Dlr.type=ielr -Dparse.lac=full -o input.c input.y]],
+               [[0]], [[]],
+[[input.y: conflicts: 2 shift/reduce
+]])
+AT_COMPILE([[input]])
+AT_PARSER_CHECK([[./input]], [[1]], [[]],
+[[syntax error, unexpected 'a', expecting 'b' or 'c'
+]])
+
+AT_CLEANUP
+
 ## ------------------------- ##
 ## Unresolved SR Conflicts.  ##
 ## ------------------------- ##
@@ -327,6 +735,62 @@ state 5
 AT_CLEANUP
 
 
+## ---------------------- ##
+## %precedence suffices.  ##
+## ---------------------- ##
+
+AT_SETUP([%precedence suffices])
+
+AT_DATA([input.y],
+[[%precedence "then"
+%precedence "else"
+%%
+stmt:
+  "if" cond "then" stmt
+| "if" cond "then" stmt "else" stmt
+| "stmt"
+;
+
+cond:
+  "exp"
+;
+]])
+
+AT_BISON_CHECK([-o input.c input.y])
+
+AT_CLEANUP
+
+
+## ------------------------------ ##
+## %precedence does not suffice.  ##
+## ------------------------------ ##
+
+AT_SETUP([%precedence does not suffice])
+
+AT_DATA([input.y],
+[[%precedence "then"
+%precedence "else"
+%%
+stmt:
+  "if" cond "then" stmt
+| "if" cond "then" stmt "else" stmt
+| "stmt"
+;
+
+cond:
+  "exp"
+| cond "then" cond
+;
+]])
+
+AT_BISON_CHECK([-o input.c input.y], 0, [],
+[[input.y: conflicts: 1 shift/reduce
+input.y:12.3-18: warning: rule useless in parser due to conflicts: cond: cond "then" cond [-Wother]
+]])
+
+AT_CLEANUP
+
+
 ## -------------------------------- ##
 ## Defaulted Conflicted Reduction.  ##
 ## -------------------------------- ##
@@ -365,7 +829,7 @@ id : '0';
 
 AT_BISON_CHECK([-o input.c --report=all input.y], 0, [],
 [[input.y: conflicts: 1 reduce/reduce
-input.y:4.6-8: warning: rule useless in parser due to conflicts: id: '0'
+input.y:4.6-8: warning: rule useless in parser due to conflicts: id: '0' [-Wother]
 ]])
 
 # Check the contents of the report.
@@ -685,13 +1149,13 @@ reported_conflicts:
 
 AT_BISON_CHECK([[--report=all input.y]], 0, [],
 [[input.y: conflicts: 1 shift/reduce, 1 reduce/reduce
-input.y:12.5-20: warning: rule useless in parser due to conflicts: resolved_conflict: 'a' unreachable1
-input.y:20.5-20: warning: rule useless in parser due to conflicts: unreachable1: 'a' unreachable2
-input.y:21.4: warning: rule useless in parser due to conflicts: unreachable1: /* empty */
-input.y:25.13: warning: rule useless in parser due to conflicts: unreachable2: /* empty */
-input.y:25.16: warning: rule useless in parser due to conflicts: unreachable2: /* empty */
-input.y:31.5-7: warning: rule useless in parser due to conflicts: reported_conflicts: 'a'
-input.y:32.4: warning: rule useless in parser due to conflicts: reported_conflicts: /* empty */
+input.y:12.5-20: warning: rule useless in parser due to conflicts: resolved_conflict: 'a' unreachable1 [-Wother]
+input.y:20.5-20: warning: rule useless in parser due to conflicts: unreachable1: 'a' unreachable2 [-Wother]
+input.y:21.4: warning: rule useless in parser due to conflicts: unreachable1: /* empty */ [-Wother]
+input.y:25.13: warning: rule useless in parser due to conflicts: unreachable2: /* empty */ [-Wother]
+input.y:25.16: warning: rule useless in parser due to conflicts: unreachable2: /* empty */ [-Wother]
+input.y:31.5-7: warning: rule useless in parser due to conflicts: reported_conflicts: 'a' [-Wother]
+input.y:32.4: warning: rule useless in parser due to conflicts: reported_conflicts: /* empty */ [-Wother]
 ]])
 
 AT_CHECK([[cat input.output]], 0,
@@ -837,10 +1301,10 @@ AT_CHECK([[cat input.y >> input-keep.y]])
 
 AT_BISON_CHECK([[input-keep.y]], 0, [],
 [[input-keep.y: conflicts: 2 shift/reduce, 2 reduce/reduce
-input-keep.y:22.4: warning: rule useless in parser due to conflicts: unreachable1: /* empty */
-input-keep.y:26.16: warning: rule useless in parser due to conflicts: unreachable2: /* empty */
-input-keep.y:32.5-7: warning: rule useless in parser due to conflicts: reported_conflicts: 'a'
-input-keep.y:33.4: warning: rule useless in parser due to conflicts: reported_conflicts: /* empty */
+input-keep.y:22.4: warning: rule useless in parser due to conflicts: unreachable1: /* empty */ [-Wother]
+input-keep.y:26.16: warning: rule useless in parser due to conflicts: unreachable2: /* empty */ [-Wother]
+input-keep.y:32.5-7: warning: rule useless in parser due to conflicts: reported_conflicts: 'a' [-Wother]
+input-keep.y:33.4: warning: rule useless in parser due to conflicts: reported_conflicts: /* empty */ [-Wother]
 ]])
 
 AT_CLEANUP
@@ -896,7 +1360,7 @@ AT_CHECK([[cat input.output | sed -n '/^state 0$/,/^state 1$/p']], 0,
    13 empty_c3: .  ['c']
 
     'b'  shift, and go to state 1
- 
+
     'c'       reduce using rule 13 (empty_c3)
     $default  reduce using rule 9 (empty_a)
 
@@ -993,3 +1457,135 @@ AT_CHECK([[cat input.output | sed -n '/^state 0$/,/^state 1$/p']], 0,
 state 1
 ]])
 AT_CLEANUP
+
+
+## -------------------- ##
+## %expect-rr non GLR.  ##
+## -------------------- ##
+
+AT_SETUP([[%expect-rr non GLR]])
+
+AT_DATA([[1.y]],
+[[%expect-rr 0
+%%
+exp: 'a'
+]])
+
+AT_BISON_CHECK([[1.y]], [[0]], [],
+[[1.y: warning: %expect-rr applies only to GLR parsers [-Wother]
+]])
+
+AT_DATA([[2.y]],
+[[%expect-rr 1
+%%
+exp: 'a' | 'a';
+]])
+
+AT_BISON_CHECK([[2.y]], [[0]], [],
+[[2.y: warning: %expect-rr applies only to GLR parsers [-Wother]
+2.y: conflicts: 1 reduce/reduce
+2.y:3.12-14: warning: rule useless in parser due to conflicts: exp: 'a' [-Wother]
+]])
+
+AT_CLEANUP
+
+
+## ---------------------------------- ##
+## -W versus %expect and %expect-rr.  ##
+## ---------------------------------- ##
+
+AT_SETUP([[-W versus %expect and %expect-rr]])
+
+AT_DATA([[sr-rr.y]],
+[[%glr-parser
+%%
+start: 'a' | A 'a' | B 'a' ;
+A: ;
+B: ;
+]])
+AT_DATA([[sr.y]],
+[[%glr-parser
+%%
+start: 'a' | A 'a' ;
+A: ;
+]])
+AT_DATA([[rr.y]],
+[[%glr-parser
+%%
+start: A | B ;
+A: ;
+B: ;
+]])
+
+AT_BISON_CHECK([[sr-rr.y]], [[0]], [[]],
+[[sr-rr.y: conflicts: 1 shift/reduce, 1 reduce/reduce
+]])
+AT_BISON_CHECK([[-Wno-conflicts-sr sr-rr.y]], [[0]], [[]],
+[[sr-rr.y: conflicts: 1 reduce/reduce
+]])
+AT_BISON_CHECK([[-Wno-conflicts-rr sr-rr.y]], [[0]], [[]],
+[[sr-rr.y: conflicts: 1 shift/reduce
+]])
+
+[for gram in sr-rr sr rr; do
+  for sr_exp_i in '' 0 1 2; do
+    for rr_exp_i in '' 0 1 2; do
+      test -z "$sr_exp_i" && test -z "$rr_exp_i" && continue
+
+      # Build grammar file.
+      sr_exp=0
+      rr_exp=0
+      file=$gram
+      directives=
+      if test -n "$sr_exp_i"; then
+        sr_exp=$sr_exp_i
+        file=$file-expect-$sr_exp
+        directives="%expect $sr_exp"
+      fi
+      if test -n "$rr_exp_i"; then
+        rr_exp=$rr_exp_i
+        file=$file-expect-rr-$rr_exp
+        directives="$directives %expect-rr $rr_exp"
+      fi
+      file=$file.y
+      echo "$directives" > $file
+      cat $gram.y >> $file
+
+      # Count actual conflicts.
+      conflicts=
+      sr_count=0
+      rr_count=0
+      if test $gram = sr || test $gram = sr-rr; then
+        conflicts="1 shift/reduce"
+        sr_count=1
+      fi
+      if test $gram = rr || test $gram = sr-rr; then
+        if test -n "$conflicts"; then
+          conflicts="$conflicts, "
+        fi
+        conflicts="${conflicts}1 reduce/reduce"
+        rr_count=1
+      fi
+
+      # Run tests.
+      if test $sr_count -eq $sr_exp && test $rr_count -eq $rr_exp; then
+        ]AT_BISON_CHECK([[-Wnone $file]])[
+        ]AT_BISON_CHECK([[-Werror $file]])[
+      else
+        echo "$file: conflicts: $conflicts" > experr
+        if test $sr_count -ne $sr_exp; then
+          if test $sr_exp -ne 1; then s=s; else s= ; fi
+          echo "$file: expected $sr_exp shift/reduce conflict$s" >> experr
+        fi
+        if test $rr_count -ne $rr_exp; then
+          if test $rr_exp -ne 1; then s=s; else s= ; fi
+          echo "$file: expected $rr_exp reduce/reduce conflict$s" >> experr
+        fi
+        ]AT_BISON_CHECK([[-Wnone $file]], [[1]], [[]], [[experr]])[
+        ]AT_BISON_CHECK([[-Werror $file]], [[1]], [[]], [[experr]])[
+      fi
+    done
+  done
+done]
+
+AT_CLEANUP