Thank the developer of the initial push parser implementation.

[bison.git] / tests / conflicts.at

diff --git a/tests/conflicts.at b/tests/conflicts.at
index 2c0178766553cd4ebad7ddc5083565239a689f9e..705419b95b8c296c685a6664540f3463470f1335 100644 (file)
--- a/tests/conflicts.at
+++ b/tests/conflicts.at
@@ -1,55 +1,78 @@
 # Exercising Bison on conflicts.                         -*- Autotest -*-
 # Exercising Bison on conflicts.                         -*- Autotest -*-

-# Copyright 2002 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
-# the Free Software Foundation; either version 2, or (at your option)
-# any later version.
+# Copyright (C) 2002-2005, 2007-2010 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
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#

 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.

-
+#

 # You should have received a copy of the GNU General Public License
 # You should have received a copy of the GNU General Public License

-# along with this program; if not, write to the Free Software
-# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
-# 02111-1307, USA.
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.

 
 AT_BANNER([[Conflicts.]])
 
 
 
 AT_BANNER([[Conflicts.]])
 
 

+## ---------------- ##
+## S/R in initial.  ##
+## ---------------- ##
+
+# I once hacked Bison in such a way that it lost its reductions on the
+# initial state (because it was confusing it with the last state).  It
+# took me a while to strip down my failures to this simple case.  So
+# make sure it finds the s/r conflict below.
+
+AT_SETUP([S/R in initial])
+
+AT_DATA([[input.y]],
+[[%expect 1
+%%
+exp: e 'e';
+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 */
+]])
+
+AT_CLEANUP
+
+

 ## ------------------- ##
 ## %nonassoc and eof.  ##
 ## ------------------- ##
 
 AT_SETUP([%nonassoc and eof])
 
 ## ------------------- ##
 ## %nonassoc and eof.  ##
 ## ------------------- ##
 
 AT_SETUP([%nonassoc and eof])
 

-AT_DATA([input.y],
+AT_DATA_GRAMMAR([input.y],

 [[
 %{
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 [[
 %{
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>

-#include <error.h>
+

 #define YYERROR_VERBOSE 1
 #define YYERROR_VERBOSE 1

-#define yyerror(Msg) \
-do { \
-  fprintf (stderr, "%s\n", Msg); \
-  exit (1); \
-} while (0)
+static void
+yyerror (const char *msg)
+{
+  fprintf (stderr, "%s\n", msg);
+}

 
 /* The current argument. */
 
 /* The current argument. */

-static const char *input = NULL;
+static const char *input;

 
 static int
 yylex (void)
 {
 
 static int
 yylex (void)
 {

-  /* No token stands for end of file. */
-  if (input && *input)
-    return *input++;
-  else
-    return 0;
+  static size_t toknum;
+  if (! (toknum <= strlen (input)))
+    abort ();
+  return input[toknum++];

 }
 
 %}
 }
 
 %}


@@ -65,77 +88,222 @@ expr: expr '<' expr
 int
 main (int argc, const char *argv[])
 {
 int
 main (int argc, const char *argv[])
 {

-  if (argc > 1)
-    input = argv[1];
+  input = argc <= 1 ? "" : argv[1];

   return yyparse ();
 }
 ]])
 
 # Specify the output files to avoid problems on different file systems.
   return yyparse ();
 }
 ]])
 
 # Specify the output files to avoid problems on different file systems.

-AT_CHECK([bison input.y -o input.c])
-AT_CHECK([$CC $CFLAGS $CPPFLAGS input.c -o input], 0, [], [ignore])
-
-AT_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_CHECK([./input '0<0<0'], [1], [],
-         [parse error, unexpected '<', expecting '<' or '>'
+AT_BISON_CHECK([-o input.c input.y])
+AT_COMPILE([input])
+
+AT_PARSER_CHECK([./input '0<0'])
+AT_PARSER_CHECK([./input '0<0<0'], [1], [],
+         [syntax error, unexpected '<'
+])
+
+AT_PARSER_CHECK([./input '0>0'])
+AT_PARSER_CHECK([./input '0>0>0'], [1], [],
+         [syntax error, unexpected '>'

 ])
 
 ])
 

-AT_CHECK([./input '0>0'])
-AT_CHECK([./input '0>0>0'], [1], [],
-         [parse error, unexpected '>', expecting '<' or '>'
+AT_PARSER_CHECK([./input '0<0>0'], [1], [],
+         [syntax error, unexpected '>'

 ])
 
 ])
 

-AT_CHECK([./input '0<0>0'], [1], [],
-         [parse error, unexpected '>', expecting '<' or '>'
+# We must disable default reductions in inconsistent states in order to
+# have an explicit list of all expected tokens.  (However, unless we use
+# canonical LR, lookahead sets are merged for different left contexts,
+# so it is still possible to have extra incorrect tokens in the expected
+# list.  That just doesn't happen to be a problem for this test case.)
+
+AT_BISON_CHECK([-Dlr.default-reductions=consistent -o input.c input.y])
+AT_COMPILE([input])
+
+AT_PARSER_CHECK([./input '0<0'])
+AT_PARSER_CHECK([./input '0<0<0'], [1], [],
+         [syntax error, unexpected '<', expecting $end
+])
+
+AT_PARSER_CHECK([./input '0>0'])
+AT_PARSER_CHECK([./input '0>0>0'], [1], [],
+         [syntax error, unexpected '>', expecting $end
+])
+
+AT_PARSER_CHECK([./input '0<0>0'], [1], [],
+         [syntax error, unexpected '>', expecting $end

 ])
 
 AT_CLEANUP
 
 
 
 ])
 
 AT_CLEANUP
 
 
 

+## ------------------------------------------- ##
+## parse.error=verbose and consistent errors.  ##
+## ------------------------------------------- ##
+
+AT_SETUP([[parse.error=verbose and consistent errors]])
+
+m4_pushdef([AT_CONSISTENT_ERRORS_CHECK], [
+
+AT_BISON_CHECK([$1[ -o input.c input.y]])
+AT_COMPILE([[input]])
+
+m4_pushdef([AT_EXPECTING], [m4_if($3, [ab], [[, expecting 'a' or 'b']],
+                                  $3, [a],  [[, expecting 'a']],
+                                  $3, [b],  [[, expecting 'b']])])
+
+AT_PARSER_CHECK([[./input]], [[1]], [],
+[[syntax error, unexpected ]$2[]AT_EXPECTING[
+]])
+
+m4_popdef([AT_EXPECTING])
+
+])
+
+AT_DATA_GRAMMAR([input.y],
+[[%code {
+  #include <assert.h>
+  #include <stdio.h>
+  int yylex (void);
+  void yyerror (char const *);
+  #define USE(Var)
+}
+
+%define parse.error verbose
+
+// The point isn't to test IELR here, but state merging happens to
+// complicate the example.
+%define lr.type ielr
+
+%nonassoc 'a'
+
+// If yylval=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 yylval=1.
+%destructor {
+  if (!$$)
+    fprintf (stderr, "Wrong destructor.\n");
+} 'a'
+
+%%
+
+// The lookahead assigned by the semantic action 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 another bug, the unexpected token is not reported
+// at all because the error action is the default action in a consistent
+// state.  That bug still needs to be fixed.
+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 ($1); }
+| /*empty*/ %prec 'a'
+;
+
+// Provide another context in which all rules are useful so that this
+// test case looks a little more realistic.
+start: 'b' consistent-error 'b' ;
+
+%%
+
+int
+yylex (void)
+{
+  static char const *input = "aa";
+  yylval = 1;
+  return *input++;
+}
+
+void
+yyerror (char const *msg)
+{
+  fprintf (stderr, "%s\n", msg);
+}
+
+int
+main (void)
+{
+  return yyparse ();
+}
+]])
+
+# See comments in grammar for why this test doesn't succeed.
+AT_XFAIL_IF([[:]])
+
+AT_CONSISTENT_ERRORS_CHECK([], [['b']], [[none]])
+AT_CONSISTENT_ERRORS_CHECK([[-Dlr.default-reductions=consistent]],
+                           [['b']], [[none]])
+
+# Canonical LR doesn't foresee the error for 'a'!
+AT_CONSISTENT_ERRORS_CHECK([[-Dlr.default-reductions=accepting]],
+                           [[$end]], [[a]])
+AT_CONSISTENT_ERRORS_CHECK([[-Flr.type=canonical-lr]], [[$end]], [[a]])
+
+m4_popdef([AT_CONSISTENT_ERRORS_CHECK])
+
+AT_CLEANUP
+
+
+

 ## ------------------------- ##
 ## Unresolved SR Conflicts.  ##
 ## ------------------------- ##
 
 AT_SETUP([Unresolved SR Conflicts])
 
 ## ------------------------- ##
 ## Unresolved SR Conflicts.  ##
 ## ------------------------- ##
 
 AT_SETUP([Unresolved SR Conflicts])
 

+AT_KEYWORDS([report])
+

 AT_DATA([input.y],
 [[%token NUM OP
 %%
 exp: exp OP exp | NUM;
 ]])
 
 AT_DATA([input.y],
 [[%token NUM OP
 %%
 exp: exp OP exp | NUM;
 ]])
 

-AT_CHECK([bison input.y -o input.c -v], 0, [],
-[input.y contains 1 shift/reduce conflict.
+AT_BISON_CHECK([-o input.c --report=all input.y], 0, [],
+[input.y: conflicts: 1 shift/reduce

 ])
 
 # Check the contents of the report.
 AT_CHECK([cat input.output], [],
 ])
 
 # Check the contents of the report.
 AT_CHECK([cat input.output], [],

-[[State 5 contains 1 shift/reduce conflict.
+[[State 5 conflicts: 1 shift/reduce

 
 
 Grammar
 
 
 
 Grammar
 

-  Number, Line, Rule
-    0   3 $axiom -> exp $
-    1   3 exp -> exp OP exp
-    2   3 exp -> NUM
+    0 $accept: exp $end
+
+    1 exp: exp OP exp
+    2    | NUM

 
 
 Terminals, with rules where they appear
 
 
 
 Terminals, with rules where they appear
 

-$ (0) 0
+$end (0) 0

 error (256)
 error (256)

-NUM (257) 2
-OP (258) 1
+NUM (258) 2
+OP (259) 1

 
 
 Nonterminals, with rules where they appear
 
 
 
 Nonterminals, with rules where they appear
 

-$axiom (5)
+$accept (5)

     on left: 0
 exp (6)
     on left: 1 2, on right: 0 1
     on left: 0
 exp (6)
     on left: 1 2, on right: 0 1


@@ -143,103 +311,102 @@ exp (6)
 
 state 0
 
 
 state 0
 

-    NUM        shift, and go to state 1
+    0 $accept: . exp $end
+    1 exp: . exp OP exp
+    2    | . NUM

 
 

-    exp        go to state 2
+    NUM  shift, and go to state 1

 
 

+    exp  go to state 2

 
 
 state 1
 
 
 
 state 1
 

-    exp  ->  NUM .   (rule 2)
-
-    $default   reduce using rule 2 (exp)
+    2 exp: NUM .

 
 

+    $default  reduce using rule 2 (exp)

 
 
 state 2
 
 
 
 state 2
 

-    $axiom  ->  exp . $   (rule 0)
-    exp  ->  exp . OP exp   (rule 1)
-
-    $          shift, and go to state 3
-    OP         shift, and go to state 4
+    0 $accept: exp . $end
+    1 exp: exp . OP exp

 
 

+    $end  shift, and go to state 3
+    OP    shift, and go to state 4

 
 
 state 3
 
 
 
 state 3
 

-    $axiom  ->  exp $ .   (rule 0)
+    0 $accept: exp $end .

 
 

-    $default   accept
+    $default  accept

 
 
 state 4
 
 
 
 state 4
 

-    exp  ->  exp OP . exp   (rule 1)
+    1 exp: . exp OP exp
+    1    | exp OP . exp
+    2    | . NUM

 
 

-    NUM        shift, and go to state 1
-
-    exp        go to state 5
+    NUM  shift, and go to state 1

 
 

+    exp  go to state 5

 
 
 state 5
 
 
 
 state 5
 

-    exp  ->  exp . OP exp   (rule 1)
-    exp  ->  exp OP exp .   (rule 1)
-
-    OP         shift, and go to state 4
-
-    OP         [reduce using rule 1 (exp)]
-    $default   reduce using rule 1 (exp)
-
+    1 exp: exp . OP exp
+    1    | exp OP exp .  [$end, OP]

 
 

+    OP  shift, and go to state 4

 
 

+    OP        [reduce using rule 1 (exp)]
+    $default  reduce using rule 1 (exp)

 ]])
 
 AT_CLEANUP
 
 
 ]])
 
 AT_CLEANUP
 
 

-## --------------------- ##
-## Solved SR Conflicts.  ##
-## --------------------- ##

 
 

-AT_SETUP([Solved SR Conflicts])
+## ----------------------- ##
+## Resolved SR Conflicts.  ##
+## ----------------------- ##
+
+AT_SETUP([Resolved SR Conflicts])
+
+AT_KEYWORDS([report])

 
 AT_DATA([input.y],
 [[%token NUM OP
 
 AT_DATA([input.y],
 [[%token NUM OP

-%right OP
+%left OP

 %%
 exp: exp OP exp | NUM;
 ]])
 
 %%
 exp: exp OP exp | NUM;
 ]])
 

-AT_CHECK([bison input.y -o input.c -v], 0, [], [])
+AT_BISON_CHECK([-o input.c --report=all input.y])

 
 # Check the contents of the report.
 AT_CHECK([cat input.output], [],
 
 # Check the contents of the report.
 AT_CHECK([cat input.output], [],

-[[Conflict in state 5 between rule 2 and token OP resolved as shift.
-
+[[Grammar

 
 

-Grammar
+    0 $accept: exp $end

 
 

-  Number, Line, Rule
-    0   4 $axiom -> exp $
-    1   4 exp -> exp OP exp
-    2   4 exp -> NUM
+    1 exp: exp OP exp
+    2    | NUM

 
 
 Terminals, with rules where they appear
 
 
 
 Terminals, with rules where they appear
 

-$ (0) 0
+$end (0) 0

 error (256)
 error (256)

-NUM (257) 2
-OP (258) 1
+NUM (258) 2
+OP (259) 1

 
 
 Nonterminals, with rules where they appear
 
 
 
 Nonterminals, with rules where they appear
 

-$axiom (5)
+$accept (5)

     on left: 0
 exp (6)
     on left: 1 2, on right: 0 1
     on left: 0
 exp (6)
     on left: 1 2, on right: 0 1


@@ -247,58 +414,251 @@ exp (6)
 
 state 0
 
 
 state 0
 

-    NUM        shift, and go to state 1
+    0 $accept: . exp $end
+    1 exp: . exp OP exp
+    2    | . NUM

 
 

-    exp        go to state 2
+    NUM  shift, and go to state 1

 
 

+    exp  go to state 2

 
 
 state 1
 
 
 
 state 1
 

-    exp  ->  NUM .   (rule 2)
-
-    $default   reduce using rule 2 (exp)
+    2 exp: NUM .

 
 

+    $default  reduce using rule 2 (exp)

 
 
 state 2
 
 
 
 state 2
 

-    $axiom  ->  exp . $   (rule 0)
-    exp  ->  exp . OP exp   (rule 1)
-
-    $          shift, and go to state 3
-    OP         shift, and go to state 4
+    0 $accept: exp . $end
+    1 exp: exp . OP exp

 
 

+    $end  shift, and go to state 3
+    OP    shift, and go to state 4

 
 
 state 3
 
 
 
 state 3
 

-    $axiom  ->  exp $ .   (rule 0)
+    0 $accept: exp $end .

 
 

-    $default   accept
+    $default  accept

 
 
 state 4
 
 
 
 state 4
 

-    exp  ->  exp OP . exp   (rule 1)
+    1 exp: . exp OP exp
+    1    | exp OP . exp
+    2    | . NUM

 
 

-    NUM        shift, and go to state 1
-
-    exp        go to state 5
+    NUM  shift, and go to state 1

 
 

+    exp  go to state 5

 
 
 state 5
 
 
 
 state 5
 

-    exp  ->  exp . OP exp   (rule 1)
-    exp  ->  exp OP exp .   (rule 1)
+    1 exp: exp . OP exp
+    1    | exp OP exp .  [$end, OP]
+
+    $default  reduce using rule 1 (exp)
+
+    Conflict between rule 1 and token OP resolved as reduce (%left OP).
+]])
+
+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
+]])
+
+AT_CLEANUP
+
+
+## -------------------------------- ##
+## Defaulted Conflicted Reduction.  ##
+## -------------------------------- ##
+
+# When there are RR conflicts, some rules are disabled.  Usually it is
+# simply displayed as:
+#
+#    $end           reduce using rule 3 (num)
+#    $end           [reduce using rule 4 (id)]
+#
+# But when `reduce 3' is the default action, we'd produce:
+#
+#    $end           [reduce using rule 4 (id)]
+#    $default    reduce using rule 3 (num)
+#
+# In this precise case (a reduction is masked by the default
+# reduction), we make the `reduce 3' explicit:
+#
+#    $end           reduce using rule 3 (num)
+#    $end           [reduce using rule 4 (id)]
+#    $default    reduce using rule 3 (num)
+#
+# Maybe that's not the best display, but then, please propose something
+# else.
+
+AT_SETUP([Defaulted Conflicted Reduction])
+AT_KEYWORDS([report])
+
+AT_DATA([input.y],
+[[%%
+exp: num | id;
+num: '0';
+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'
+]])
+
+# Check the contents of the report.
+AT_CHECK([cat input.output], [],
+[[Rules useless in parser due to conflicts
+
+    4 id: '0'
+
+
+State 1 conflicts: 1 reduce/reduce
+

 
 

-    OP         shift, and go to state 4
+Grammar
+
+    0 $accept: exp $end
+
+    1 exp: num
+    2    | id
+
+    3 num: '0'
+
+    4 id: '0'
+
+
+Terminals, with rules where they appear
+
+$end (0) 0
+'0' (48) 3 4
+error (256)
+
+
+Nonterminals, with rules where they appear
+
+$accept (4)
+    on left: 0
+exp (5)
+    on left: 1 2, on right: 0
+num (6)
+    on left: 3, on right: 1
+id (7)
+    on left: 4, on right: 2
+
+
+state 0
+
+    0 $accept: . exp $end
+    1 exp: . num
+    2    | . id
+    3 num: . '0'
+    4 id: . '0'
+
+    '0'  shift, and go to state 1
+
+    exp  go to state 2
+    num  go to state 3
+    id   go to state 4

 
 

-    $default   reduce using rule 1 (exp)

 
 

+state 1
+
+    3 num: '0' .  [$end]
+    4 id: '0' .  [$end]
+
+    $end      reduce using rule 3 (num)
+    $end      [reduce using rule 4 (id)]
+    $default  reduce using rule 3 (num)
+
+
+state 2
+
+    0 $accept: exp . $end
+
+    $end  shift, and go to state 5
+
+
+state 3
+
+    1 exp: num .
+
+    $default  reduce using rule 1 (exp)
+
+
+state 4
+
+    2 exp: id .
+
+    $default  reduce using rule 2 (exp)
+
+
+state 5

 
 

+    0 $accept: exp $end .

 
 

+    $default  accept

 ]])
 
 AT_CLEANUP
 ]])
 
 AT_CLEANUP


@@ -319,9 +679,9 @@ AT_DATA([input.y],
 exp: exp OP exp | NUM;
 ]])
 
 exp: exp OP exp | NUM;
 ]])
 

-AT_CHECK([bison input.y -o input.c], 1, [],
-[input.y contains 1 shift/reduce conflict.
-expected 0 shift/reduce conflicts
+AT_BISON_CHECK([-o input.c input.y], 1, [],
+[input.y: conflicts: 1 shift/reduce
+input.y: expected 0 shift/reduce conflicts

 ])
 AT_CLEANUP
 
 ])
 AT_CLEANUP
 


@@ -339,7 +699,7 @@ AT_DATA([input.y],
 exp: exp OP exp | NUM;
 ]])
 
 exp: exp OP exp | NUM;
 ]])
 

-AT_CHECK([bison input.y -o input.c], 0)
+AT_BISON_CHECK([-o input.c input.y])

 AT_CLEANUP
 
 
 AT_CLEANUP
 
 


@@ -356,8 +716,479 @@ AT_DATA([input.y],
 exp: exp OP exp | NUM;
 ]])
 
 exp: exp OP exp | NUM;
 ]])
 

-AT_CHECK([bison input.y -o input.c], 1, [],
-[input.y contains 1 shift/reduce conflict.
-expected 2 shift/reduce conflicts
+AT_BISON_CHECK([-o input.c input.y], 1, [],
+[input.y: conflicts: 1 shift/reduce
+input.y: expected 2 shift/reduce conflicts

 ])
 AT_CLEANUP
 ])
 AT_CLEANUP

+
+
+## ------------------------------- ##
+## %expect with reduce conflicts.  ##
+## ------------------------------- ##
+
+AT_SETUP([%expect with reduce conflicts])
+
+AT_DATA([input.y],
+[[%expect 0
+%%
+program: a 'a' | a a;
+a: 'a';
+]])
+
+AT_BISON_CHECK([-o input.c input.y], 1, [],
+[input.y: conflicts: 1 reduce/reduce
+input.y: expected 0 reduce/reduce conflicts
+])
+AT_CLEANUP
+
+
+## ------------------------- ##
+## %prec with user strings.  ##
+## ------------------------- ##
+
+AT_SETUP([%prec with user string])
+
+AT_DATA([[input.y]],
+[[%%
+exp:
+  "foo" %prec "foo"
+;
+]])
+
+AT_BISON_CHECK([-o input.c input.y])
+AT_CLEANUP
+
+
+## -------------------------------- ##
+## %no-default-prec without %prec.  ##
+## -------------------------------- ##
+
+AT_SETUP([%no-default-prec without %prec])
+
+AT_DATA([[input.y]],
+[[%left '+'
+%left '*'
+
+%%
+
+%no-default-prec;
+
+e:   e '+' e
+   | e '*' e
+   | '0'
+   ;
+]])
+
+AT_BISON_CHECK([-o input.c input.y], 0, [],
+[[input.y: conflicts: 4 shift/reduce
+]])
+AT_CLEANUP
+
+
+## ----------------------------- ##
+## %no-default-prec with %prec.  ##
+## ----------------------------- ##
+
+AT_SETUP([%no-default-prec with %prec])
+
+AT_DATA([[input.y]],
+[[%left '+'
+%left '*'
+
+%%
+
+%no-default-prec;
+
+e:   e '+' e %prec '+'
+   | e '*' e %prec '*'
+   | '0'
+   ;
+]])
+
+AT_BISON_CHECK([-o input.c input.y])
+AT_CLEANUP
+
+
+## --------------- ##
+## %default-prec.  ##
+## --------------- ##
+
+AT_SETUP([%default-prec])
+
+AT_DATA([[input.y]],
+[[%left '+'
+%left '*'
+
+%%
+
+%default-prec;
+
+e:   e '+' e
+   | e '*' e
+   | '0'
+   ;
+]])
+
+AT_BISON_CHECK([-o input.c input.y])
+AT_CLEANUP
+
+
+## ---------------------------------------------- ##
+## Unreachable States After Conflict Resolution.  ##
+## ---------------------------------------------- ##
+
+AT_SETUP([[Unreachable States After Conflict Resolution]])
+
+# If conflict resolution makes states unreachable, remove those states, report
+# rules that are then unused, and don't report conflicts in those states.  Test
+# what happens when a nonterminal becomes useless as a result of state removal
+# since that causes lalr.o's goto map to be rewritten.
+
+AT_DATA([[input.y]],
+[[%output "input.c"
+%left 'a'
+
+%%
+
+start: resolved_conflict 'a' reported_conflicts 'a' ;
+
+/* S/R conflict resolved as reduce, so the state with item
+ * (resolved_conflict: 'a' . unreachable1) and all it transition successors are
+ * unreachable, and the associated production is useless.  */
+resolved_conflict:
+    'a' unreachable1
+  | %prec 'a'
+  ;
+
+/* S/R conflict that need not be reported since it is unreachable because of
+ * the previous conflict resolution.  Nonterminal unreachable1 and all its
+ * productions are useless.  */
+unreachable1:
+    'a' unreachable2
+  |
+  ;
+
+/* Likewise for a R/R conflict and nonterminal unreachable2.  */
+unreachable2: | ;
+
+/* Make sure remaining S/R and R/R conflicts are still reported correctly even
+ * when their states are renumbered due to state removal.  */
+reported_conflicts:
+    'a'
+  | 'a'
+  |
+  ;
+
+]])
+
+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 */
+]])
+
+AT_CHECK([[cat input.output]], 0,
+[[Rules useless in parser due to conflicts
+
+    2 resolved_conflict: 'a' unreachable1
+
+    4 unreachable1: 'a' unreachable2
+    5             | /* empty */
+
+    6 unreachable2: /* empty */
+    7             | /* empty */
+
+    9 reported_conflicts: 'a'
+   10                   | /* empty */
+
+
+State 4 conflicts: 1 shift/reduce
+State 5 conflicts: 1 reduce/reduce
+
+
+Grammar
+
+    0 $accept: start $end
+
+    1 start: resolved_conflict 'a' reported_conflicts 'a'
+
+    2 resolved_conflict: 'a' unreachable1
+    3                  | /* empty */
+
+    4 unreachable1: 'a' unreachable2
+    5             | /* empty */
+
+    6 unreachable2: /* empty */
+    7             | /* empty */
+
+    8 reported_conflicts: 'a'
+    9                   | 'a'
+   10                   | /* empty */
+
+
+Terminals, with rules where they appear
+
+$end (0) 0
+'a' (97) 1 2 4 8 9
+error (256)
+
+
+Nonterminals, with rules where they appear
+
+$accept (4)
+    on left: 0
+start (5)
+    on left: 1, on right: 0
+resolved_conflict (6)
+    on left: 2 3, on right: 1
+unreachable1 (7)
+    on left: 4 5, on right: 2
+unreachable2 (8)
+    on left: 6 7, on right: 4
+reported_conflicts (9)
+    on left: 8 9 10, on right: 1
+
+
+state 0
+
+    0 $accept: . start $end
+    1 start: . resolved_conflict 'a' reported_conflicts 'a'
+    2 resolved_conflict: . 'a' unreachable1
+    3                  | .  ['a']
+
+    $default  reduce using rule 3 (resolved_conflict)
+
+    start              go to state 1
+    resolved_conflict  go to state 2
+
+    Conflict between rule 3 and token 'a' resolved as reduce (%left 'a').
+
+
+state 1
+
+    0 $accept: start . $end
+
+    $end  shift, and go to state 3
+
+
+state 2
+
+    1 start: resolved_conflict . 'a' reported_conflicts 'a'
+
+    'a'  shift, and go to state 4
+
+
+state 3
+
+    0 $accept: start $end .
+
+    $default  accept
+
+
+state 4
+
+    1 start: resolved_conflict 'a' . reported_conflicts 'a'
+    8 reported_conflicts: . 'a'
+    9                   | . 'a'
+   10                   | .  ['a']
+
+    'a'  shift, and go to state 5
+
+    'a'  [reduce using rule 10 (reported_conflicts)]
+
+    reported_conflicts  go to state 6
+
+
+state 5
+
+    8 reported_conflicts: 'a' .  ['a']
+    9                   | 'a' .  ['a']
+
+    'a'       reduce using rule 8 (reported_conflicts)
+    'a'       [reduce using rule 9 (reported_conflicts)]
+    $default  reduce using rule 8 (reported_conflicts)
+
+
+state 6
+
+    1 start: resolved_conflict 'a' reported_conflicts . 'a'
+
+    'a'  shift, and go to state 7
+
+
+state 7
+
+    1 start: resolved_conflict 'a' reported_conflicts 'a' .
+
+    $default  reduce using rule 1 (start)
+]])
+
+AT_DATA([[input-keep.y]],
+[[%define lr.keep-unreachable-states
+]])
+AT_CHECK([[cat input.y >> input-keep.y]])
+
+AT_BISON_CHECK([[input-keep.y]], 0, [],
+[[input-keep.y: conflicts: 2 shift/reduce, 2 reduce/reduce
+input-keep.y:22.4: warning: rule useless in parser due to conflicts: unreachable1: /* empty */
+input-keep.y:26.16: warning: rule useless in parser due to conflicts: unreachable2: /* empty */
+input-keep.y:32.5-7: warning: rule useless in parser due to conflicts: reported_conflicts: 'a'
+input-keep.y:33.4: warning: rule useless in parser due to conflicts: reported_conflicts: /* empty */
+]])
+
+AT_CLEANUP
+
+
+## ------------------------------------------------------------ ##
+## Solved conflicts report for multiple reductions in a state.  ##
+## ------------------------------------------------------------ ##
+
+AT_SETUP([[Solved conflicts report for multiple reductions in a state]])
+
+# Used to lose earlier solved conflict messages even within a single S/R/R.
+
+AT_DATA([[input.y]],
+[[%left 'a'
+%right 'b'
+%right 'c'
+%right 'd'
+%%
+start:
+    'a'
+  | empty_a 'a'
+  | 'b'
+  | empty_b 'b'
+  | 'c'
+  | empty_c1 'c'
+  | empty_c2 'c'
+  | empty_c3 'c'
+  ;
+empty_a: %prec 'a' ;
+empty_b: %prec 'b' ;
+empty_c1: %prec 'c' ;
+empty_c2: %prec 'c' ;
+empty_c3: %prec 'd' ;
+]])
+AT_BISON_CHECK([[--report=all -o input.c input.y]], 0, [], [ignore])
+AT_CHECK([[cat input.output | sed -n '/^state 0$/,/^state 1$/p']], 0,
+[[state 0
+
+    0 $accept: . start $end
+    1 start: . 'a'
+    2      | . empty_a 'a'
+    3      | . 'b'
+    4      | . empty_b 'b'
+    5      | . 'c'
+    6      | . empty_c1 'c'
+    7      | . empty_c2 'c'
+    8      | . empty_c3 'c'
+    9 empty_a: .  ['a']
+   10 empty_b: .  []
+   11 empty_c1: .  []
+   12 empty_c2: .  []
+   13 empty_c3: .  ['c']
+
+    'b'  shift, and go to state 1
+
+    'c'       reduce using rule 13 (empty_c3)
+    $default  reduce using rule 9 (empty_a)
+
+    start     go to state 2
+    empty_a   go to state 3
+    empty_b   go to state 4
+    empty_c1  go to state 5
+    empty_c2  go to state 6
+    empty_c3  go to state 7
+
+    Conflict between rule 9 and token 'a' resolved as reduce (%left 'a').
+    Conflict between rule 10 and token 'b' resolved as shift (%right 'b').
+    Conflict between rule 11 and token 'c' resolved as shift (%right 'c').
+    Conflict between rule 12 and token 'c' resolved as shift (%right 'c').
+    Conflict between rule 13 and token 'c' resolved as reduce ('c' < 'd').
+
+
+state 1
+]])
+
+AT_CLEANUP
+
+
+## ------------------------------------------------------------ ##
+## %nonassoc error actions for multiple reductions in a state.  ##
+## ------------------------------------------------------------ ##
+
+# Used to abort when trying to resolve conflicts as %nonassoc error actions for
+# multiple reductions in a state.
+
+# For a %nonassoc error action token, used to print the first remaining
+# reduction on that token without brackets.
+
+AT_SETUP([[%nonassoc error actions for multiple reductions in a state]])
+
+AT_DATA([[input.y]],
+[[%nonassoc 'a' 'b' 'c'
+%%
+start:
+    'a'
+  | empty_a 'a'
+  | 'b'
+  | empty_b 'b'
+  | 'c'
+  | empty_c1 'c'
+  | empty_c2 'c'
+  | empty_c3 'c'
+  ;
+empty_a: %prec 'a' ;
+empty_b: %prec 'b' ;
+empty_c1: %prec 'c' ;
+empty_c2: %prec 'c' ;
+empty_c3: %prec 'c' ;
+]])
+
+AT_BISON_CHECK([[--report=all -o input.c input.y]], 0, [], [ignore])
+AT_CHECK([[cat input.output | sed -n '/^state 0$/,/^state 1$/p']], 0,
+[[state 0
+
+    0 $accept: . start $end
+    1 start: . 'a'
+    2      | . empty_a 'a'
+    3      | . 'b'
+    4      | . empty_b 'b'
+    5      | . 'c'
+    6      | . empty_c1 'c'
+    7      | . empty_c2 'c'
+    8      | . empty_c3 'c'
+    9 empty_a: .  []
+   10 empty_b: .  []
+   11 empty_c1: .  []
+   12 empty_c2: .  ['c']
+   13 empty_c3: .  ['c']
+
+    'a'  error (nonassociative)
+    'b'  error (nonassociative)
+    'c'  error (nonassociative)
+
+    'c'  [reduce using rule 12 (empty_c2)]
+    'c'  [reduce using rule 13 (empty_c3)]
+
+    start     go to state 1
+    empty_a   go to state 2
+    empty_b   go to state 3
+    empty_c1  go to state 4
+    empty_c2  go to state 5
+    empty_c3  go to state 6
+
+    Conflict between rule 9 and token 'a' resolved as an error (%nonassoc 'a').
+    Conflict between rule 10 and token 'b' resolved as an error (%nonassoc 'b').
+    Conflict between rule 11 and token 'c' resolved as an error (%nonassoc 'c').
+
+
+state 1
+]])
+AT_CLEANUP