Severity Code Description Project File Line Suppression State Warning C4244 '=': conversion from '__int64' to 'I32', possible loss of data C:\Strawberry\perl\lib\CORE\inline.h 2165

Above is the warning we are getting.

When you go to link 2165 of inline.h this is line of code: PL_curstackinfo->si_cxsubix = cx - PL_curstackinfo->si_cxstack; Looking at PL_curstackinfoyou get (from cop.h):

struct stackinfo {
    AV *                  si_stack;               /* stack for current
+ runlevel */
    PERL_CONTEXT *         si_cxstack;          /* context stack for r
+unlevel */
    struct stackinfo *         si_prev;
    struct stackinfo *         si_next;
    I32                                      si_cxix; /* current conte
+xt index */
    I32                                      si_cxmax;            /* m
+aximum allocated index */
    I32                                      si_cxsubix;         /* to
+pmost sub/eval/format */
    I32                                      si_type; /* type of runle
+vel */
    I32                                      si_markoff;         /* of
+fset where markstack begins for us.
                                                                      
+          * currently used only with DEBUGGING,
                                                                      
+          * but not #ifdef-ed for bincompat */
#if defined DEBUGGING && !defined DEBUGGING_RE_ONLY
/* high water mark: for checking if the stack was correctly extended /
* tested for extension by each pp function */
    SSize_t             si_stack_hwm;
#endif

};
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Here we can see that si_sxsubix is defined as an I32 which is typdef long I32. si_cxstack is a pointer to a PERL_CONTEXT. The key here is the fact it’s a pointer.

PERL_CONTEXT *cx
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Going back to the line of code that is getting the warning:

PL_curstackinfo->si_cxsubix = cx - PL_curstackinfo->si_cxstack;
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cx is going to be the address to a PERL_CONTEXT The problem is that when compiling for 64bit systems an address is going to be 64bits so now when doing the subtraction and putting it into the 32bit si_cxsubix there’s a conversation issue because the 64bit subtraction is being put into a 32bit value.