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The Basics
Id: 75313
Status: resolved
Priority: 0/
Queue: Mouse

Owner: Nobody in particular
Requestors: 'spro^^*%*^6ut# [...] &$%*c
Cc: ANDK [...]

Bug Information
Severity: Critical
Broken in: (no value)
Fixed in: (no value)

CC: DDUMONT [...], ANDK [...]
Subject: Bad ERRSV handling in BUILD call
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mouse_call_sv_safe in MouseUtil.xs has these two lines: SAVESPTR(ERRSV); ERRSV = sv_newmortal(); The problem with setting $@ to a temp variable with a refcount of 1 is that perl thinks it can steal its string buffer, resulting in bugs like this: use Test::More tests => 1; {use Mouse} sub BUILD { $@ = "foo"; my $x = $@; is $@, "foo"; # fails because $@ is undef } new main; __END__ (This is the cause of CPAN bug #74900.) In fact, by using SAVESPTR for a refcounted location, you are causing the temps stack and *@{SCALAR} both to share the same refcount. Or another way of putting it is that *@{SCALAR} is no longer refcounted, but the rest of perl doesn’t know that. That results in bugs like this: {use Mouse} sub BUILD { $foo = \$@; *@ = \my $x; } new main; use Devel::Peek; Dump $$foo __END__ The output is something like this: SV = UNKNOWN(0xff) (0x82ae80) at 0x82adf0 REFCNT = 0 FLAGS = () So a scalar with refcount of 0 becomes accessible to Perl space. I believe by changing those two lines to SAVEGENERICSV(ERRSV); ERRSV = SvREFCNT_inc(sv_newmortal()); you can fix the bugs, but I haven’t actually tested it.
Thanks! It is fixed in 0.98. -- Goro Fuji (gfx) GFUJI at

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