Re: [bug-gawk] gawk internal error on $i++

[Aharon Robbins]

Hi Ed.

> Date: Mon, 07 Oct 2013 08:17:48 -0500
> From: Ed Morton <address@hidden>
> To: address@hidden
> CC: Arnold Robbins <address@hidden>
> Subject: gawk internal error on $i++
>
> On cygwin on Windows 7:
>
>     $ awk 'BEGIN{ $i++ = 3; print i }'
>     awk: cmd. line:1: fatal: internal error line 5032, file: awkgram.y
>
>     $ awk --version
>     GNU Awk 4.1.0, API: 1.0 (GNU MPFR 3.1.2, GNU MP 5.1.2)
>
>     $ bash --version
>     GNU bash, version 4.1.11(2)-release (x86_64-unknown-cygwin)

Thanks for the report.

Yes, it's a bug.  The following patch handles this specific case and
also improves the error message for "the next time".

I will push this in the next day or two.

Arnold

------------------------------------------
diff --git a/awkgram.y b/awkgram.y
index f0ff4f0..2cfffae 100644
--- a/awkgram.y
+++ b/awkgram.y
@@ -5028,8 +5028,13 @@ mk_assignment(INSTRUCTION *lhs, INSTRUCTION *rhs, 
INSTRUCTION *op)
        case Op_push_array:
                tp->opcode = Op_push_lhs; 
                break;
+       case Op_field_assign:
+               yyerror(_("cannot assign a value to the result of a field 
post-increment expression"));
+               break;
        default:
-               cant_happen();
+               fatal(_("internal error: mk_assignment received `%s' opcode"),
+                               opcode2str(tp->opcode));
+               break;
        }
 
        tp->do_reference = (op->opcode != Op_assign);   /* check for 
uninitialized reference */