diff options
| -rw-r--r-- | gv.c | 20 |
1 files changed, 19 insertions, 1 deletions
@@ -2058,7 +2058,18 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags, symtab yet. */ if (SvTYPE(gv) == SVt_PVGV) { + /* The GV already exists, so return it, but check if we need to do + * anything else with it before that. + */ if (add) { + /* This is the heuristic that handles if a variable triggers the + * 'used only once' warning. If there's already a GV in the stash + * with this name, then we assume that the variable has been used + * before and turn its MULTI flag on. + * It's a heuristic because it can easily be "tricked", like with + * BEGIN { $a = 1; $::{foo} = *a }; () = $foo + * not warning about $main::foo being used just once + */ GvMULTI_on(gv); gv_init_svtype(gv, sv_type); /* You reach this path once the typeglob has already been created, @@ -2110,7 +2121,14 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags, } else if (no_init) { assert(!addmg); return gv; - } else if (no_expand && SvROK(gv)) { + } + /* If GV_NOEXPAND is true and what we got off the stash is a ref, + * don't expand it to a glob. This is an optimization so that things + * copying constants over, like Exporter, don't have to be rewritten + * to take into account that you can store more than just globs in + * stashes. + */ + else if (no_expand && SvROK(gv)) { assert(!addmg); return gv; } |