From 390fe0c0d09aadc66f644e9eee4aa1245221188c Mon Sep 17 00:00:00 2001
From: David Mitchell <davem@iabyn.com>
Date: Tue, 25 Aug 2020 13:15:25 +0100
Subject: [PATCH] sort { return foo() } ...
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GH #18081
A sub call via return in a sort block was called in void rather than
scalar context, causing the comparison result to be discarded.
This because when a sort block is called it is not a real function
call, even though a sort block can be returned from. Instead, a
CXt_NULL is pushed on the context stack. Because this isn't a sub-ish
context type (unlike CXt_SUB, CXt_EVAL etc) there is no 'caller sub'
on the context stack to be found to retrieve the caller's context
(i.e. cx->cx_gimme).
This commit fixes it by special-casing Perl_gimme_V().
Ideally at some future point, a new context type, CXt_SORT, should be
added. This would be used instead of CXt_NULL when a sort BLOCK is
called. Like other sub-ish context types, it would have an old_cxsubix
field and PL_curstackinfo->si_cxsubix would point to it. This would
eliminate needing special-case handling in places like Perl_gimme_V().
Signed-off-by: Petr Písař <ppisar@redhat.com>
---
inline.h | 2 +-
t/op/sort.t | 12 +++++++++++-
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/inline.h b/inline.h
index a8240efb9c..6fbd5abfea 100644
--- a/inline.h
+++ b/inline.h
@@ -2086,7 +2086,7 @@ Perl_gimme_V(pTHX)
return gimme;
cxix = PL_curstackinfo->si_cxsubix;
if (cxix < 0)
- return G_VOID;
+ return PL_curstackinfo->si_type == PERLSI_SORT ? G_SCALAR: G_VOID;
assert(cxstack[cxix].blk_gimme & G_WANT);
return (cxstack[cxix].blk_gimme & G_WANT);
}
diff --git a/t/op/sort.t b/t/op/sort.t
index f2e139dff0..8e387fb90d 100644
--- a/t/op/sort.t
+++ b/t/op/sort.t
@@ -7,7 +7,7 @@ BEGIN {
set_up_inc('../lib');
}
use warnings;
-plan(tests => 203);
+plan(tests => 204);
use Tie::Array; # we need to test sorting tied arrays
# these shouldn't hang
@@ -1202,3 +1202,13 @@ SKIP:
$fillb = undef;
is $act, "01[sortb]2[fillb]";
}
+
+# GH #18081
+# sub call via return in sort block was called in void rather than scalar
+# context
+
+{
+ sub sort18081 { $a + 1 <=> $b + 1 }
+ my @a = sort { return &sort18081 } 6,1,2;
+ is "@a", "1 2 6", "GH #18081";
+}
--
2.25.4