From: Nicholas Clark <nick@ccl4.org>
Date: Tue, 22 Apr 2008 15:01:52 +0000 (+0000)
Subject: Note that Rafael did the key elsif() line number TODO, and we're not
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=18a16cc57227b924e697696433dd9183b2f690e1;p=p5sagit%2Fp5-mst-13.2.git

Note that Rafael did the key elsif() line number TODO, and we're not
certain that solving the general case is worth it.

p4raw-id: //depot/perl@33724
---

diff --git a/pod/perltodo.pod b/pod/perltodo.pod
index f4e81f1..bd45433 100644
--- a/pod/perltodo.pod
+++ b/pod/perltodo.pod
@@ -924,17 +924,18 @@ This code
     } elsif ($undef == 0) {
     }
 
-produces this output
+used to produce this output:
 
     Use of uninitialized value in numeric eq (==) at wrong.pl line 4.
     Use of uninitialized value in numeric eq (==) at wrong.pl line 4.
 
-Clearly the line of the second warning is misreported - it should be line 5.
-
-The problem arises because there is no nextstate op between the execution of
-the C<if> and the C<elsif>, hence C<PL_curcop> still reports that the currently
-executing line is line 4. The solution might be to inject (somehow) more
-nextstate ops, one for each C<elsif>.
+where the line of the second warning was misreported - it should be line 5.
+Rafael fixed this - the problem arose because there was no nextstate OP
+between the execution of the C<if> and the C<elsif>, hence C<PL_curcop> still
+reports that the currently executing line is line 4. The solution was to inject
+a nextstate OPs for each C<elsif>, although it turned out that the nextstate
+OP needed to be a nulled OP, rather than a live nextstate OP, else other line
+numbers became misreported. (Jenga!)
 
 The problem is more general than C<elsif> (although the C<elsif> case is the
 most common and the most confusing). Ideally this code
@@ -968,6 +969,9 @@ do not store the line number. (Which, logically, why it would work best in
 conjunction with L</repack the optree>, as that is already copying/reallocating
 all the OPs)
 
+(Although I should note that we're not certain that doing this for the general
+case is worth it)
+
 =head2 optimize tail-calls
 
 Tail-calls present an opportunity for broadly applicable optimization;