make sure "use VERSION;" sets the flag needed for "used only once" #21284
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There's two parts to producing the "used only once" warning: 1. In a lexical scope with WARN_ONCE enabled, new GVs are created with the GVf_MULTI flag off, a second mention of such a name will set that flag. 2. After compilation, if G_WARN_ONCE is set in PL_dowarn, the entire package tree is walked to report names which don't have GVf_MULTI set. In this case G_WARN_ONCE wasn't being set, so the second part didn't happen. This flag is global, so using any other module that happened to enable the WARN_ONCE flag (anything that does C<use warnings;>) would allow warnings to be produced after compilation. Fixes Perl#21271
leonerd
approved these changes
Jul 24, 2023
Leont
approved these changes
Jul 24, 2023
tonycoz
added
backport-5.36
backport-5.38
|
I've added this to both votes-5,36.xml and votes-5.38.xml in maint-votes. Vote early, vote often. |
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There's two parts to producing the "used only once" warning:
In a lexical scope with WARN_ONCE enabled, new GVs are created with the GVf_MULTI flag off, a second mention of such a name will set that flag.
After compilation, if G_WARN_ONCE is set in PL_dowarn, the entire package tree is walked to report names which don't have GVf_MULTI set.
In this case G_WARN_ONCE wasn't being set, so the second part didn't happen.
This flag is global, so using any other module that happened to enable the WARN_ONCE flag (anything that does C<use warnings;>) would allow warnings to be produced after compilation.
Fixes #21271