[rt.cpan.org #133081] [cperl] panic: attempt to copy freed scalar ... to ... at <embedded>/Tie/Hash/NamedCapture.pm

Thu Jul 30 08:35:46 2020: Request 133081 was acted upon.
Transaction: Ticket created by RSCHUPP
Queue: PAR-Packer
Subject: [cperl] panic: attempt to copy freed scalar ... to ... at
<embedded>/Tie/Hash/NamedCapture.pm
Broken in: (no value)
Severity: (no value)
Owner: Nobody
Requestors: [email protected]
Status: new
Ticket <URL: https://rt.cpan.org/Ticket/Display.html?id=133081 >


When building PAR::Packer with cperl (at least 5.28.2c, 5.30.0c) almost all test fail
with the same error message:

$ pp -o a.exe -E 0
panic: attempt to copy freed scalar 55c95f55e3e0 to 55c95f55dde0 at <embedded>/Tie/Hash/NamedCapture.pm line 7.
Compilation failed in require at -e line 140.

This is caused by cperl moving XSLoader from an external XSLoader.pm module directly into DynaLoader.so, hence patching XSLoader.pm via PAR::Filter::PatchContent doesn't work anymore.

As reminder to myself: looks like the following is happening:

1. pp runs (in PAR::Packer::_generate_output)
parl -B -Oa.exe some.par

2. loads Tie/Hash/NamedCapture.pm with demangled name from the cache area

3. loads NamedCapture.so from the install location (_not_ the demangled copy from
the cache area though it is present) and calls boot_Tie__Hash__NamedCapture
which panics

At that point (2) and (3) have worked successfully for lots of other "embedded" modules,
so I dunno why Tie::Hash::NamedCapture behaves differently.
But the real problem is that dynamic loading of mangled DLLs from the cache area
doesn't work, because intercepting dynamic loading doesn't work without the
patch to XSLoader.