Fixing Perl5 Core Bugs: Report for Month 28

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Dave Mitchell writes:

As per my grant conditions, here is a report for the June period.

This month saw the final merging of my re_eval branch back into blead, and incorporated in the 5.17.1 release. This consisted of about 125 commits, spread out over a year. The remainder of the month was spent fixing some of the issues thrown up by the new implementation.

Some highlights of the new /(?{})/ implementation are:

Code blocks within patterns are now parsed in the same pass as the surrounding code; in particular it is no longer necessary to have balanced braces: this now works:

/(?{ $x='{' })/

This means that this error message is longer generated:

Sequence (?{...}) not terminated or not {}-balanced in regex

but a new error may be seen:

Sequence (?{...}) not terminated with ')'

In addition, literal code blocks within run-time patterns are only compiled once, at perl compile-time:

for my $p (...) {
    # this 'FOO' block of code is compiled once, at the same time as
    # the surrounding 'for' loop

Lexical variables are now sane as regards scope, recursion and closure behaviour. In particular, /A(?{B})C/ behaves (from a closure viewpoint) exactly like /A/ && do { B } && /C/, while qr/A(?{B})C/ is like sub {/A/ && do { B } && /C/}. So this code now works how you might expect, creating three regexes that match 1,2, and 3:

for my $i (0..2) {
    push @r, qr/^(??{$i})$/;
"1" =~ $r[1]; # matches

The use re 'eval' pragma is now strictly only required for code blocks defined at runtime; in particular in the following, the text of the $r@ pattern is still interpolated into the new pattern and recompiled, but the individual compiled code-blocks within @$r are reused rather than being recompiled, and use re 'eval' isn't needed any more:

my $r = qr/abc(?{....})def/;

Flow control operators no longer crash. Each code block runs in a new dynamic scope, so next etc. will not see any enclosing loops and caller will not see any calling subroutines. return returns a value from the code block, not from any enclosing subroutine.

Over the last month I have averaged 15 hours per week.

As of 2012/06/31: since the beginning of the grant:

120.9 weeks
1300.0 total hours
10.8 average hours per week

There are now 0 hours left on the grant (but the grant has just been extended :-)

Report for period 2012/06/01 to 2012/06/30 inclusive


Effort (HH::MM):

23:50 diagnosing bugs
39:03 fixing bugs
0:00 reviewing other people's bug fixes
0:00 reviewing ticket histories
0:00 review the ticket queue (triage)
62:53 Total

Numbers of tickets closed:

4 tickets closed that have been worked on
0 tickets closed related to bugs that have been fixed
0 tickets closed that were reviewed but not worked on (triage)
4 Total

[actually, an additional 25 tickets were closed, but I forgot to update my automatic log]

Short Detail

8:42 [perl #3634] Capture corruption through self-modying regexp (?{...})
36:41 [perl #34161] METABUG - (?{...}) and (??{...}) regexp issues
4:25 [perl #113670] Bleadperl v5.17.0-451-gf6033a9 breaks SBECK/Date-Manip-6.32.tar.gz
2:00 [perl #113676] Bleadperl v5.17.0-383-g9f14173 breaks PARDUS/File-MimeInfo/File-MimeInfo-0.16.tar.gz
10:05 [perl #113682] Bleadperl v5.17.0-424-gd24ca0c breaks ABIGAIL/Regexp-Common-2011121001.tar.gz
1:00 [perl #113720] perl dumping core in regex et al(mem corruption?)

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This page contains a single entry by Karen published on July 13, 2012 8:36 AM.

2012Q3 Call for Grant Proposals was the previous entry in this blog.

Devel::Cover Grant Report for June is the next entry in this blog.

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