[perl #24684] Too late warning not given for CHECK block in INIT block

Thanks for the report.

This is because when nothing is actually happening in the main scope of
the program it's treated as an OP_STUB which causes Perl_newPROG() to
skip out before setting PL_main_start; which is what the warning requires:

(Inside of Perl_newprog()):

         if (o->op_type == OP_STUB) {
            PL_comppad_name = 0;
            PL_compcv = 0;
            S_op_destroy(aTHX_ o);

            return; < -- Returns here
        }
        PL_main_root = op_scope(sawparens(scalarvoid(o)));
        PL_curcop = &PL_compiling;
        PL_main_start = LINKLIST(PL_main_root); < -- This is needed

(The warning check:)

                if (PL_main_start)
                    Perl_ck_warner(aTHX_ packWARN(WARN_VOID),
                                   "Too late to run CHECK block");

This warns correctly for example:

 perl -we'INIT { eval "CHECK {print qq:in check in init\n:}" } print "hi";'

Since the CHECK blocks don't actually get run, the warning should still
get generated. Does PL_main_start (and PL_main_root, etc..) need to get
set even when it's just an OP_STUB?  Or is this an unlikely / illogical
situation?

-- Matthew Horsfall (alh)

• Re: [perl #24684] Too late warning not given for CHECK block in INIT block by Yitzchak Scott-Thoennes
• [perl #24684] Too late warning not given for CHECK block in INIT block by Matthew Horsfall via RT
• [perl #24684] Too late warning not given for CHECK block in INIT block by Father Chrysostomos via RT
• [perl #24684] Too late warning not given for CHECK block in INIT block by Father Chrysostomos via RT