tests/conflicts.at

   1 # Exercising Bison on conflicts.                         -*- Autotest -*-
   2
   3 # Copyright (C) 2002, 2003, 2004, 2005, 2007, 2009 Free Software
   4 # Foundation, Inc.
   5
   6 # This program is free software: you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation, either version 3 of the License, or
   9 # (at your option) any later version.
  10 #
  11 # This program is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 # GNU General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU General Public License
  17 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18
  19 AT_BANNER([[Conflicts.]])
  20
  21
  22 ## ---------------- ##
  23 ## S/R in initial.  ##
  24 ## ---------------- ##
  25
  26 # I once hacked Bison in such a way that it lost its reductions on the
  27 # initial state (because it was confusing it with the last state).  It
  28 # took me a while to strip down my failures to this simple case.  So
  29 # make sure it finds the s/r conflict below.
  30
  31 AT_SETUP([S/R in initial])
  32
  33 AT_DATA([[input.y]],
  34 [[%expect 1
  35 %%
  36 exp: e 'e';
  37 e: 'e' | /* Nothing. */;
  38 ]])
  39
  40 AT_BISON_CHECK([-o input.c input.y], 0, [],
  41 [[input.y:4.9: warning: rule useless in parser due to conflicts: e: /* empty */
  42 ]])
  43
  44 AT_CLEANUP
  45
  46
  47 ## ------------------- ##
  48 ## %nonassoc and eof.  ##
  49 ## ------------------- ##
  50
  51 AT_SETUP([%nonassoc and eof])
  52
  53 AT_DATA_GRAMMAR([input.y],
  54 [[
  55 %{
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59
  60 #define YYERROR_VERBOSE 1
  61 static void
  62 yyerror (const char *msg)
  63 {
  64   fprintf (stderr, "%s\n", msg);
  65 }
  66
  67 /* The current argument. */
  68 static const char *input;
  69
  70 static int
  71 yylex (void)
  72 {
  73   static size_t toknum;
  74   if (! (toknum <= strlen (input)))
  75     abort ();
  76   return input[toknum++];
  77 }
  78
  79 %}
  80
  81 %nonassoc '<' '>'
  82
  83 %%
  84 expr: expr '<' expr
  85     | expr '>' expr
  86     | '0'
  87     ;
  88 %%
  89 int
  90 main (int argc, const char *argv[])
  91 {
  92   input = argc <= 1 ? "" : argv[1];
  93   return yyparse ();
  94 }
  95 ]])
  96
  97 # Specify the output files to avoid problems on different file systems.
  98 AT_BISON_CHECK([-o input.c input.y])
  99 AT_COMPILE([input])
 100
 101 AT_PARSER_CHECK([./input '0<0'])
 102 # FIXME: This is an actual bug, but a new one, in the sense that
 103 # no one has ever spotted it!  The messages are *wrong*: there should
 104 # be nothing there, it should be expected eof.
 105 AT_PARSER_CHECK([./input '0<0<0'], [1], [],
 106          [syntax error, unexpected '<', expecting '<' or '>'
 107 ])
 108
 109 AT_PARSER_CHECK([./input '0>0'])
 110 AT_PARSER_CHECK([./input '0>0>0'], [1], [],
 111          [syntax error, unexpected '>', expecting '<' or '>'
 112 ])
 113
 114 AT_PARSER_CHECK([./input '0<0>0'], [1], [],
 115          [syntax error, unexpected '>', expecting '<' or '>'
 116 ])
 117
 118 AT_CLEANUP
 119
 120
 121
 122 ## ------------------------- ##
 123 ## Unresolved SR Conflicts.  ##
 124 ## ------------------------- ##
 125
 126 AT_SETUP([Unresolved SR Conflicts])
 127
 128 AT_KEYWORDS([report])
 129
 130 AT_DATA([input.y],
 131 [[%token NUM OP
 132 %%
 133 exp: exp OP exp | NUM;
 134 ]])
 135
 136 AT_BISON_CHECK([-o input.c --report=all input.y], 0, [],
 137 [input.y: conflicts: 1 shift/reduce
 138 ])
 139
 140 # Check the contents of the report.
 141 AT_CHECK([cat input.output], [],
 142 [[State 5 conflicts: 1 shift/reduce
 143
 144
 145 Grammar
 146
 147     0 $accept: exp $end
 148
 149     1 exp: exp OP exp
 150     2    | NUM
 151
 152
 153 Terminals, with rules where they appear
 154
 155 $end (0) 0
 156 error (256)
 157 NUM (258) 2
 158 OP (259) 1
 159
 160
 161 Nonterminals, with rules where they appear
 162
 163 $accept (5)
 164     on left: 0
 165 exp (6)
 166     on left: 1 2, on right: 0 1
 167
 168
 169 state 0
 170
 171     0 $accept: . exp $end
 172     1 exp: . exp OP exp
 173     2    | . NUM
 174
 175     NUM  shift, and go to state 1
 176
 177     exp  go to state 2
 178
 179
 180 state 1
 181
 182     2 exp: NUM .
 183
 184     $default  reduce using rule 2 (exp)
 185
 186
 187 state 2
 188
 189     0 $accept: exp . $end
 190     1 exp: exp . OP exp
 191
 192     $end  shift, and go to state 3
 193     OP    shift, and go to state 4
 194
 195
 196 state 3
 197
 198     0 $accept: exp $end .
 199
 200     $default  accept
 201
 202
 203 state 4
 204
 205     1 exp: . exp OP exp
 206     1    | exp OP . exp
 207     2    | . NUM
 208
 209     NUM  shift, and go to state 1
 210
 211     exp  go to state 5
 212
 213
 214 state 5
 215
 216     1 exp: exp . OP exp
 217     1    | exp OP exp .  [$end, OP]
 218
 219     OP  shift, and go to state 4
 220
 221     OP        [reduce using rule 1 (exp)]
 222     $default  reduce using rule 1 (exp)
 223 ]])
 224
 225 AT_CLEANUP
 226
 227
 228
 229 ## ----------------------- ##
 230 ## Resolved SR Conflicts.  ##
 231 ## ----------------------- ##
 232
 233 AT_SETUP([Resolved SR Conflicts])
 234
 235 AT_KEYWORDS([report])
 236
 237 AT_DATA([input.y],
 238 [[%token NUM OP
 239 %left OP
 240 %%
 241 exp: exp OP exp | NUM;
 242 ]])
 243
 244 AT_BISON_CHECK([-o input.c --report=all input.y])
 245
 246 # Check the contents of the report.
 247 AT_CHECK([cat input.output], [],
 248 [[Grammar
 249
 250     0 $accept: exp $end
 251
 252     1 exp: exp OP exp
 253     2    | NUM
 254
 255
 256 Terminals, with rules where they appear
 257
 258 $end (0) 0
 259 error (256)
 260 NUM (258) 2
 261 OP (259) 1
 262
 263
 264 Nonterminals, with rules where they appear
 265
 266 $accept (5)
 267     on left: 0
 268 exp (6)
 269     on left: 1 2, on right: 0 1
 270
 271
 272 state 0
 273
 274     0 $accept: . exp $end
 275     1 exp: . exp OP exp
 276     2    | . NUM
 277
 278     NUM  shift, and go to state 1
 279
 280     exp  go to state 2
 281
 282
 283 state 1
 284
 285     2 exp: NUM .
 286
 287     $default  reduce using rule 2 (exp)
 288
 289
 290 state 2
 291
 292     0 $accept: exp . $end
 293     1 exp: exp . OP exp
 294
 295     $end  shift, and go to state 3
 296     OP    shift, and go to state 4
 297
 298
 299 state 3
 300
 301     0 $accept: exp $end .
 302
 303     $default  accept
 304
 305
 306 state 4
 307
 308     1 exp: . exp OP exp
 309     1    | exp OP . exp
 310     2    | . NUM
 311
 312     NUM  shift, and go to state 1
 313
 314     exp  go to state 5
 315
 316
 317 state 5
 318
 319     1 exp: exp . OP exp
 320     1    | exp OP exp .  [$end, OP]
 321
 322     $default  reduce using rule 1 (exp)
 323
 324     Conflict between rule 1 and token OP resolved as reduce (%left OP).
 325 ]])
 326
 327 AT_CLEANUP
 328
 329
 330 ## -------------------------------- ##
 331 ## Defaulted Conflicted Reduction.  ##
 332 ## -------------------------------- ##
 333
 334 # When there are RR conflicts, some rules are disabled.  Usually it is
 335 # simply displayed as:
 336 #
 337 #    $end           reduce using rule 3 (num)
 338 #    $end           [reduce using rule 4 (id)]
 339 #
 340 # But when `reduce 3' is the default action, we'd produce:
 341 #
 342 #    $end           [reduce using rule 4 (id)]
 343 #    $default    reduce using rule 3 (num)
 344 #
 345 # In this precise case (a reduction is masked by the default
 346 # reduction), we make the `reduce 3' explicit:
 347 #
 348 #    $end           reduce using rule 3 (num)
 349 #    $end           [reduce using rule 4 (id)]
 350 #    $default    reduce using rule 3 (num)
 351 #
 352 # Maybe that's not the best display, but then, please propose something
 353 # else.
 354
 355 AT_SETUP([Defaulted Conflicted Reduction])
 356 AT_KEYWORDS([report])
 357
 358 AT_DATA([input.y],
 359 [[%%
 360 exp: num | id;
 361 num: '0';
 362 id : '0';
 363 %%
 364 ]])
 365
 366 AT_BISON_CHECK([-o input.c --report=all input.y], 0, [],
 367 [[input.y: conflicts: 1 reduce/reduce
 368 input.y:4.6-8: warning: rule useless in parser due to conflicts: id: '0'
 369 ]])
 370
 371 # Check the contents of the report.
 372 AT_CHECK([cat input.output], [],
 373 [[Rules useless in parser due to conflicts
 374
 375     4 id: '0'
 376
 377
 378 State 1 conflicts: 1 reduce/reduce
 379
 380
 381 Grammar
 382
 383     0 $accept: exp $end
 384
 385     1 exp: num
 386     2    | id
 387
 388     3 num: '0'
 389
 390     4 id: '0'
 391
 392
 393 Terminals, with rules where they appear
 394
 395 $end (0) 0
 396 '0' (48) 3 4
 397 error (256)
 398
 399
 400 Nonterminals, with rules where they appear
 401
 402 $accept (4)
 403     on left: 0
 404 exp (5)
 405     on left: 1 2, on right: 0
 406 num (6)
 407     on left: 3, on right: 1
 408 id (7)
 409     on left: 4, on right: 2
 410
 411
 412 state 0
 413
 414     0 $accept: . exp $end
 415     1 exp: . num
 416     2    | . id
 417     3 num: . '0'
 418     4 id: . '0'
 419
 420     '0'  shift, and go to state 1
 421
 422     exp  go to state 2
 423     num  go to state 3
 424     id   go to state 4
 425
 426
 427 state 1
 428
 429     3 num: '0' .  [$end]
 430     4 id: '0' .  [$end]
 431
 432     $end      reduce using rule 3 (num)
 433     $end      [reduce using rule 4 (id)]
 434     $default  reduce using rule 3 (num)
 435
 436
 437 state 2
 438
 439     0 $accept: exp . $end
 440
 441     $end  shift, and go to state 5
 442
 443
 444 state 3
 445
 446     1 exp: num .
 447
 448     $default  reduce using rule 1 (exp)
 449
 450
 451 state 4
 452
 453     2 exp: id .
 454
 455     $default  reduce using rule 2 (exp)
 456
 457
 458 state 5
 459
 460     0 $accept: exp $end .
 461
 462     $default  accept
 463 ]])
 464
 465 AT_CLEANUP
 466
 467
 468
 469
 470 ## -------------------- ##
 471 ## %expect not enough.  ##
 472 ## -------------------- ##
 473
 474 AT_SETUP([%expect not enough])
 475
 476 AT_DATA([input.y],
 477 [[%token NUM OP
 478 %expect 0
 479 %%
 480 exp: exp OP exp | NUM;
 481 ]])
 482
 483 AT_BISON_CHECK([-o input.c input.y], 1, [],
 484 [input.y: conflicts: 1 shift/reduce
 485 input.y: expected 0 shift/reduce conflicts
 486 ])
 487 AT_CLEANUP
 488
 489
 490 ## --------------- ##
 491 ## %expect right.  ##
 492 ## --------------- ##
 493
 494 AT_SETUP([%expect right])
 495
 496 AT_DATA([input.y],
 497 [[%token NUM OP
 498 %expect 1
 499 %%
 500 exp: exp OP exp | NUM;
 501 ]])
 502
 503 AT_BISON_CHECK([-o input.c input.y])
 504 AT_CLEANUP
 505
 506
 507 ## ------------------ ##
 508 ## %expect too much.  ##
 509 ## ------------------ ##
 510
 511 AT_SETUP([%expect too much])
 512
 513 AT_DATA([input.y],
 514 [[%token NUM OP
 515 %expect 2
 516 %%
 517 exp: exp OP exp | NUM;
 518 ]])
 519
 520 AT_BISON_CHECK([-o input.c input.y], 1, [],
 521 [input.y: conflicts: 1 shift/reduce
 522 input.y: expected 2 shift/reduce conflicts
 523 ])
 524 AT_CLEANUP
 525
 526
 527 ## ------------------------------ ##
 528 ## %expect with reduce conflicts  ##
 529 ## ------------------------------ ##
 530
 531 AT_SETUP([%expect with reduce conflicts])
 532
 533 AT_DATA([input.y],
 534 [[%expect 0
 535 %%
 536 program: a 'a' | a a;
 537 a: 'a';
 538 ]])
 539
 540 AT_BISON_CHECK([-o input.c input.y], 1, [],
 541 [input.y: conflicts: 1 reduce/reduce
 542 input.y: expected 0 reduce/reduce conflicts
 543 ])
 544 AT_CLEANUP
 545
 546
 547 ## ------------------------------- ##
 548 ## %no-default-prec without %prec  ##
 549 ## ------------------------------- ##
 550
 551 AT_SETUP([%no-default-prec without %prec])
 552
 553 AT_DATA([[input.y]],
 554 [[%left '+'
 555 %left '*'
 556
 557 %%
 558
 559 %no-default-prec;
 560
 561 e:   e '+' e
 562    | e '*' e
 563    | '0'
 564    ;
 565 ]])
 566
 567 AT_BISON_CHECK([-o input.c input.y], 0, [],
 568 [[input.y: conflicts: 4 shift/reduce
 569 ]])
 570 AT_CLEANUP
 571
 572
 573 ## ---------------------------- ##
 574 ## %no-default-prec with %prec  ##
 575 ## ---------------------------- ##
 576
 577 AT_SETUP([%no-default-prec with %prec])
 578
 579 AT_DATA([[input.y]],
 580 [[%left '+'
 581 %left '*'
 582
 583 %%
 584
 585 %no-default-prec;
 586
 587 e:   e '+' e %prec '+'
 588    | e '*' e %prec '*'
 589    | '0'
 590    ;
 591 ]])
 592
 593 AT_BISON_CHECK([-o input.c input.y])
 594 AT_CLEANUP
 595
 596
 597 ## ---------------- ##
 598 ## %default-prec    ##
 599 ## ---------------- ##
 600
 601 AT_SETUP([%default-prec])
 602
 603 AT_DATA([[input.y]],
 604 [[%left '+'
 605 %left '*'
 606
 607 %%
 608
 609 %default-prec;
 610
 611 e:   e '+' e
 612    | e '*' e
 613    | '0'
 614    ;
 615 ]])
 616
 617 AT_BISON_CHECK([-o input.c input.y])
 618 AT_CLEANUP
 619
 620
 621 ## ---------------------------------------------- ##
 622 ## Unreachable States After Conflict Resolution.  ##
 623 ## ---------------------------------------------- ##
 624
 625 AT_SETUP([[Unreachable States After Conflict Resolution]])
 626
 627 # If conflict resolution makes states unreachable, remove those states, report
 628 # rules that are then unused, and don't report conflicts in those states.  Test
 629 # what happens when a nonterminal becomes useless as a result of state removal
 630 # since that causes lalr.o's goto map to be rewritten.
 631
 632 AT_DATA([[input.y]],
 633 [[%output "input.c"
 634 %left 'a'
 635
 636 %%
 637
 638 start: resolved_conflict 'a' reported_conflicts 'a' ;
 639
 640 /* S/R conflict resolved as reduce, so the state with item
 641  * (resolved_conflict: 'a' . unreachable1) and all it transition successors are
 642  * unreachable, and the associated production is useless.  */
 643 resolved_conflict:
 644     'a' unreachable1
 645   | %prec 'a'
 646   ;
 647
 648 /* S/R conflict that need not be reported since it is unreachable because of
 649  * the previous conflict resolution.  Nonterminal unreachable1 and all its
 650  * productions are useless.  */
 651 unreachable1:
 652     'a' unreachable2
 653   |
 654   ;
 655
 656 /* Likewise for a R/R conflict and nonterminal unreachable2.  */
 657 unreachable2: | ;
 658
 659 /* Make sure remaining S/R and R/R conflicts are still reported correctly even
 660  * when their states are renumbered due to state removal.  */
 661 reported_conflicts:
 662     'a'
 663   | 'a'
 664   |
 665   ;
 666
 667 ]])
 668
 669 AT_BISON_CHECK([[--report=all input.y]], 0, [],
 670 [[input.y: conflicts: 1 shift/reduce, 1 reduce/reduce
 671 input.y:12.5-20: warning: rule useless in parser due to conflicts: resolved_conflict: 'a' unreachable1
 672 input.y:20.5-20: warning: rule useless in parser due to conflicts: unreachable1: 'a' unreachable2
 673 input.y:21.4: warning: rule useless in parser due to conflicts: unreachable1: /* empty */
 674 input.y:25.13: warning: rule useless in parser due to conflicts: unreachable2: /* empty */
 675 input.y:25.16: warning: rule useless in parser due to conflicts: unreachable2: /* empty */
 676 input.y:31.5-7: warning: rule useless in parser due to conflicts: reported_conflicts: 'a'
 677 input.y:32.4: warning: rule useless in parser due to conflicts: reported_conflicts: /* empty */
 678 ]])
 679
 680 AT_CHECK([[cat input.output]], 0,
 681 [[Rules useless in parser due to conflicts
 682
 683     2 resolved_conflict: 'a' unreachable1
 684
 685     4 unreachable1: 'a' unreachable2
 686     5             | /* empty */
 687
 688     6 unreachable2: /* empty */
 689     7             | /* empty */
 690
 691     9 reported_conflicts: 'a'
 692    10                   | /* empty */
 693
 694
 695 State 4 conflicts: 1 shift/reduce
 696 State 5 conflicts: 1 reduce/reduce
 697
 698
 699 Grammar
 700
 701     0 $accept: start $end
 702
 703     1 start: resolved_conflict 'a' reported_conflicts 'a'
 704
 705     2 resolved_conflict: 'a' unreachable1
 706     3                  | /* empty */
 707
 708     4 unreachable1: 'a' unreachable2
 709     5             | /* empty */
 710
 711     6 unreachable2: /* empty */
 712     7             | /* empty */
 713
 714     8 reported_conflicts: 'a'
 715     9                   | 'a'
 716    10                   | /* empty */
 717
 718
 719 Terminals, with rules where they appear
 720
 721 $end (0) 0
 722 'a' (97) 1 2 4 8 9
 723 error (256)
 724
 725
 726 Nonterminals, with rules where they appear
 727
 728 $accept (4)
 729     on left: 0
 730 start (5)
 731     on left: 1, on right: 0
 732 resolved_conflict (6)
 733     on left: 2 3, on right: 1
 734 unreachable1 (7)
 735     on left: 4 5, on right: 2
 736 unreachable2 (8)
 737     on left: 6 7, on right: 4
 738 reported_conflicts (9)
 739     on left: 8 9 10, on right: 1
 740
 741
 742 state 0
 743
 744     0 $accept: . start $end
 745     1 start: . resolved_conflict 'a' reported_conflicts 'a'
 746     2 resolved_conflict: . 'a' unreachable1
 747     3                  | .  ['a']
 748
 749     $default  reduce using rule 3 (resolved_conflict)
 750
 751     start              go to state 1
 752     resolved_conflict  go to state 2
 753
 754     Conflict between rule 3 and token 'a' resolved as reduce (%left 'a').
 755
 756
 757 state 1
 758
 759     0 $accept: start . $end
 760
 761     $end  shift, and go to state 3
 762
 763
 764 state 2
 765
 766     1 start: resolved_conflict . 'a' reported_conflicts 'a'
 767
 768     'a'  shift, and go to state 4
 769
 770
 771 state 3
 772
 773     0 $accept: start $end .
 774
 775     $default  accept
 776
 777
 778 state 4
 779
 780     1 start: resolved_conflict 'a' . reported_conflicts 'a'
 781     8 reported_conflicts: . 'a'
 782     9                   | . 'a'
 783    10                   | .  ['a']
 784
 785     'a'  shift, and go to state 5
 786
 787     'a'  [reduce using rule 10 (reported_conflicts)]
 788
 789     reported_conflicts  go to state 6
 790
 791
 792 state 5
 793
 794     8 reported_conflicts: 'a' .  ['a']
 795     9                   | 'a' .  ['a']
 796
 797     'a'       reduce using rule 8 (reported_conflicts)
 798     'a'       [reduce using rule 9 (reported_conflicts)]
 799     $default  reduce using rule 8 (reported_conflicts)
 800
 801
 802 state 6
 803
 804     1 start: resolved_conflict 'a' reported_conflicts . 'a'
 805
 806     'a'  shift, and go to state 7
 807
 808
 809 state 7
 810
 811     1 start: resolved_conflict 'a' reported_conflicts 'a' .
 812
 813     $default  reduce using rule 1 (start)
 814 ]])
 815
 816 AT_DATA([[input-keep.y]],
 817 [[%define lr.keep_unreachable_states
 818 ]])
 819 AT_CHECK([[cat input.y >> input-keep.y]])
 820
 821 AT_BISON_CHECK([[input-keep.y]], 0, [],
 822 [[input-keep.y: conflicts: 2 shift/reduce, 2 reduce/reduce
 823 input-keep.y:22.4: warning: rule useless in parser due to conflicts: unreachable1: /* empty */
 824 input-keep.y:26.16: warning: rule useless in parser due to conflicts: unreachable2: /* empty */
 825 input-keep.y:32.5-7: warning: rule useless in parser due to conflicts: reported_conflicts: 'a'
 826 input-keep.y:33.4: warning: rule useless in parser due to conflicts: reported_conflicts: /* empty */
 827 ]])
 828
 829 AT_CLEANUP
 830
 831
 832 ## ------------------------------------------------------------ ##
 833 ## Solved conflicts report for multiple reductions in a state.  ##
 834 ## ------------------------------------------------------------ ##
 835
 836 AT_SETUP([[Solved conflicts report for multiple reductions in a state]])
 837
 838 # Used to lose earlier solved conflict messages even within a single S/R/R.
 839
 840 AT_DATA([[input.y]],
 841 [[%left 'a'
 842 %right 'b'
 843 %right 'c'
 844 %right 'd'
 845 %%
 846 start:
 847     'a'
 848   | empty_a 'a'
 849   | 'b'
 850   | empty_b 'b'
 851   | 'c'
 852   | empty_c1 'c'
 853   | empty_c2 'c'
 854   | empty_c3 'c'
 855   ;
 856 empty_a: %prec 'a' ;
 857 empty_b: %prec 'b' ;
 858 empty_c1: %prec 'c' ;
 859 empty_c2: %prec 'c' ;
 860 empty_c3: %prec 'd' ;
 861 ]])
 862 AT_BISON_CHECK([[--report=all -o input.c input.y]], 0, [], [ignore])
 863 AT_CHECK([[cat input.output | sed -n '/^state 0$/,/^state 1$/p']], 0,
 864 [[state 0
 865
 866     0 $accept: . start $end
 867     1 start: . 'a'
 868     2      | . empty_a 'a'
 869     3      | . 'b'
 870     4      | . empty_b 'b'
 871     5      | . 'c'
 872     6      | . empty_c1 'c'
 873     7      | . empty_c2 'c'
 874     8      | . empty_c3 'c'
 875     9 empty_a: .  ['a']
 876    10 empty_b: .  []
 877    11 empty_c1: .  []
 878    12 empty_c2: .  []
 879    13 empty_c3: .  ['c']
 880
 881     'b'  shift, and go to state 1
 882
 883     'c'       reduce using rule 13 (empty_c3)
 884     $default  reduce using rule 9 (empty_a)
 885
 886     start     go to state 2
 887     empty_a   go to state 3
 888     empty_b   go to state 4
 889     empty_c1  go to state 5
 890     empty_c2  go to state 6
 891     empty_c3  go to state 7
 892
 893     Conflict between rule 9 and token 'a' resolved as reduce (%left 'a').
 894     Conflict between rule 10 and token 'b' resolved as shift (%right 'b').
 895     Conflict between rule 11 and token 'c' resolved as shift (%right 'c').
 896     Conflict between rule 12 and token 'c' resolved as shift (%right 'c').
 897     Conflict between rule 13 and token 'c' resolved as reduce ('c' < 'd').
 898
 899
 900 state 1
 901 ]])
 902
 903 AT_CLEANUP
 904
 905
 906 ## ------------------------------------------------------------ ##
 907 ## %nonassoc error actions for multiple reductions in a state.  ##
 908 ## ------------------------------------------------------------ ##
 909
 910 # Used to abort when trying to resolve conflicts as %nonassoc error actions for
 911 # multiple reductions in a state.
 912
 913 # For a %nonassoc error action token, used to print the first remaining
 914 # reduction on that token without brackets.
 915
 916 AT_SETUP([[%nonassoc error actions for multiple reductions in a state]])
 917
 918 AT_DATA([[input.y]],
 919 [[%nonassoc 'a' 'b' 'c'
 920 %%
 921 start:
 922     'a'
 923   | empty_a 'a'
 924   | 'b'
 925   | empty_b 'b'
 926   | 'c'
 927   | empty_c1 'c'
 928   | empty_c2 'c'
 929   | empty_c3 'c'
 930   ;
 931 empty_a: %prec 'a' ;
 932 empty_b: %prec 'b' ;
 933 empty_c1: %prec 'c' ;
 934 empty_c2: %prec 'c' ;
 935 empty_c3: %prec 'c' ;
 936 ]])
 937
 938 AT_BISON_CHECK([[--report=all -o input.c input.y]], 0, [], [ignore])
 939 AT_CHECK([[cat input.output | sed -n '/^state 0$/,/^state 1$/p']], 0,
 940 [[state 0
 941
 942     0 $accept: . start $end
 943     1 start: . 'a'
 944     2      | . empty_a 'a'
 945     3      | . 'b'
 946     4      | . empty_b 'b'
 947     5      | . 'c'
 948     6      | . empty_c1 'c'
 949     7      | . empty_c2 'c'
 950     8      | . empty_c3 'c'
 951     9 empty_a: .  []
 952    10 empty_b: .  []
 953    11 empty_c1: .  []
 954    12 empty_c2: .  ['c']
 955    13 empty_c3: .  ['c']
 956
 957     'a'  error (nonassociative)
 958     'b'  error (nonassociative)
 959     'c'  error (nonassociative)
 960
 961     'c'  [reduce using rule 12 (empty_c2)]
 962     'c'  [reduce using rule 13 (empty_c3)]
 963
 964     start     go to state 1
 965     empty_a   go to state 2
 966     empty_b   go to state 3
 967     empty_c1  go to state 4
 968     empty_c2  go to state 5
 969     empty_c3  go to state 6
 970
 971     Conflict between rule 9 and token 'a' resolved as an error (%nonassoc 'a').
 972     Conflict between rule 10 and token 'b' resolved as an error (%nonassoc 'b').
 973     Conflict between rule 11 and token 'c' resolved as an error (%nonassoc 'c').
 974
 975
 976 state 1
 977 ]])
 978 AT_CLEANUP