in reply to Inline::C - object accessor failure

I haven't used Inline::C very much, so I'm not really familiar with its idiosyncracies. I would have expected this:

use Inline 'C' => <<CEND; SV* x (HV* self) { SV** x_ref = hv_fetch( self, "x", 1, 0 ); return (x_ref ? *x_ref : &PL_sv_undef); } CEND
to work, but in fact it causes some nasty internal warnings:
Attempt to free temp prematurely: SV 0x816f1c4. Attempt to free unreferenced scalar: SV 0x816f1c4.
You'll only get the warnings if you have a DEBUGGING compile of perl, but they indicate a real problem! I'm not certain, but I would guess this is actually a bug in Inline::C. Update: it's actually a feature of XS – see rest of thread. Thanks sfink!

It seems that the following works correctly:

use Inline 'C' => <<CEND; void x (HV* self) { SV** x_ref = hv_fetch( self, "x", 1, 0 ); Inline_Stack_Vars; Inline_Stack_Reset; Inline_Stack_Push (x_ref ? *x_ref : &PL_sv_undef); Inline_Stack_Done; } CEND