cex: clean the display of conflicted symbols

[Akim Demaille]

commit 1ec93ca2a2b4718b5d94871475520a2688b4c5c8
Author: Akim Demaille <address@hidden>
Date:   Sat May 23 18:17:57 2020 +0200

    cex: clean the display of conflicted symbols
    
    Instead of `On Symbols: {b,c,}`, display `On Symbols: b, c`.
    
    * src/counterexample.c (counterexample_report_reduce_reduce): We don't
    need braces.
    Use commas as a separator, not a terminator.
    * tests/counterexample.at: Adjust.

diff --git a/src/counterexample.c b/src/counterexample.c
index d5dca5e3..90ab72f7 100644
--- a/src/counterexample.c
+++ b/src/counterexample.c
@@ -19,15 +19,16 @@
 
 #include <config.h>
 
-#include <time.h>
-#include <hash.h>
-#include <stdlib.h>
+#include "counterexample.h"
+
 #include <gl_linked_list.h>
 #include <gl_rbtreehash_list.h>
+#include <hash.h>
+#include <stdlib.h>
+#include <time.h>
 
 #include "closure.h"
 #include "complain.h"
-#include "counterexample.h"
 #include "derivation.h"
 #include "getargs.h"
 #include "gram.h"
@@ -1202,11 +1203,15 @@ counterexample_report_reduce_reduce (state_item_number 
itm1, state_item_number i
   fputs ("Reduce-Reduce Conflict:\n", out);
   print_state_item (&state_items[itm1], out);
   print_state_item (&state_items[itm2], out);
-  fputs ("On Symbols: {", out);
+  fputs ("On Symbols: ", out);
   bitset_iterator biter;
   state_item_number sym;
+  const char *sep = "";
   BITSET_FOR_EACH (biter, conflict_syms, sym, 0)
-    fprintf (out, "%s,", symbols[sym]->tag);
-  fputs ("}\n", out);
+    {
+      fprintf (out, "%s%s", sep, symbols[sym]->tag);
+      sep = ", ";
+    }
+  fputs ("\n", out);
   counterexample_report (itm1, itm2, bitset_first (conflict_syms), false);
 }
diff --git a/tests/counterexample.at b/tests/counterexample.at
index 09a354cd..6cddb501 100644
--- a/tests/counterexample.at
+++ b/tests/counterexample.at
@@ -261,7 +261,7 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[Reduce-Reduce Conflict:
 4:    1 a: A b .
 4:    3 b: b .
-On Symbols: {$end,}
+On Symbols: $end
 Example  A  b  •
 First  derivation  a ::=[ A  b  • ]
 Second derivation  a ::=[ A  b ::=[ b  • ] ]
@@ -291,7 +291,7 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[Reduce-Reduce Conflict:
 2:    5 a: D .
 2:    6 b: D .
-On Symbols: {A,C,}
+On Symbols: A, C
 First  Example D  •  A  $end
 First  derivation  $accept ::=[ s ::=[ a ::=[ D  • ]  A ]  $end ]
 Second Example B  D  •  A  $end
@@ -393,7 +393,7 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[Reduce-Reduce Conflict:
 3:    3 A: B .
 3:    5 A: . %empty
-On Symbols: {b,c,}
+On Symbols: b, c
 Example  B  •  b  A  A  c  A
 First  derivation  S ::=[ B ::=[ A ::=[ B  • ]  b  A ]  C ::=[ A  c  A ] ]
 Second derivation  S ::=[ B  C ::=[ A ::=[ B ::=[ A ::=[ • ]  b  A ] ]  c  A ] 
]
@@ -401,7 +401,7 @@ Second derivation  S ::=[ B  C ::=[ A ::=[ B ::=[ A ::=[ • 
]  b  A ] ]  c  A ]
 Reduce-Reduce Conflict:
 4:    4 A: C .
 4:    5 A: . %empty
-On Symbols: {b,c,}
+On Symbols: b, c
 Example  C  •  c  A  A  b  A
 First  derivation  S ::=[ C ::=[ A ::=[ C  • ]  c  A ]  B ::=[ A  b  A ] ]
 Second derivation  S ::=[ C  B ::=[ A ::=[ C ::=[ A ::=[ • ]  c  A ] ]  b  A ] 
]
@@ -431,7 +431,7 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[Reduce-Reduce Conflict:
 0:    3 b: . %empty
 0:    4 c: . %empty
-On Symbols: {A,}
+On Symbols: A
 First  Example •  c  A  A  $end
 First  derivation  $accept ::=[ a ::=[ b ::=[ • ]  d ::=[ c  A  A ] ]  $end ]
 Second Example •  c  A  A  $end
@@ -470,7 +470,7 @@ Second derivation  a ::=[ b  d ::=[ c  •  A ] ]
 Reduce-Reduce Conflict:
 6:    3 b: . %empty
 6:    4 c: . %empty
-On Symbols: {A,}
+On Symbols: A
 First  Example b  c  •  c  A  A  $end
 First  derivation  $accept ::=[ a ::=[ b  d ::=[ a ::=[ c  d ::=[ a ::=[ b 
::=[ • ]  d ::=[ c  A  A ] ] ] ] ] ]  $end ]
 Second Example b  c  •  A  $end
@@ -488,7 +488,7 @@ Second derivation  a ::=[ b  d ::=[ c  •  A ] ]
 Reduce-Reduce Conflict:
 7:    1 a: b d .
 7:    7 d: d .
-On Symbols: {$end,}
+On Symbols: $end
 Example  b  d  •
 First  derivation  a ::=[ b  d  • ]
 Second derivation  a ::=[ b  d ::=[ d  • ] ]
@@ -496,7 +496,7 @@ Second derivation  a ::=[ b  d ::=[ d  • ] ]
 Reduce-Reduce Conflict:
 8:    2 a: c d .
 8:    7 d: d .
-On Symbols: {$end,}
+On Symbols: $end
 Example  c  d  •
 First  derivation  a ::=[ c  d  • ]
 Second derivation  a ::=[ c  d ::=[ d  • ] ]