tests/conflicts.at

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