constant pragma doesn't warn on redefinition of a list constant #20742
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I've reproduced this and I see the cause. While reviewing the code I found a related problem: Both that and the reported issue are core bugs rather than bugs in constant.pm |
tonycoz
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Feb 1, 2023
The code in report_redefined_cv() would check whether the old constant and the new constant were the same SV to avoid warning on duplicate imports of the same constant. Since both gv_setref() and report_redefined_cv() used cv_const_sv() to fetch the constant SV, which returns NULL for an AV based constant sub, the check for the equivalent SV would compare NULL to NULL and report_redefined_cv() would return early. Additional checks were required further down to prevent sv_cmp() being called on AVs. The check for simple SV's allow redefinition of constant subs if the new value string compares the same as the old value. The AV check does not try to allow that. Fixed Perl#20742
tonycoz
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Feb 8, 2023
The code in report_redefined_cv() would check whether the old constant and the new constant were the same SV to avoid warning on duplicate imports of the same constant. Since both gv_setref() and report_redefined_cv() used cv_const_sv() to fetch the constant SV, which returns NULL for an AV based constant sub, the check for the equivalent SV would compare NULL to NULL and report_redefined_cv() would return early. Additional checks were required further down to prevent sv_cmp() being called on AVs. The check for simple SV's allow redefinition of constant subs if the new value string compares the same as the old value. The AV check does not try to allow that. Fixed #20742
pjacklam
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May 20, 2023
The code in report_redefined_cv() would check whether the old constant and the new constant were the same SV to avoid warning on duplicate imports of the same constant. Since both gv_setref() and report_redefined_cv() used cv_const_sv() to fetch the constant SV, which returns NULL for an AV based constant sub, the check for the equivalent SV would compare NULL to NULL and report_redefined_cv() would return early. Additional checks were required further down to prevent sv_cmp() being called on AVs. The check for simple SV's allow redefinition of constant subs if the new value string compares the same as the old value. The AV check does not try to allow that. Fixed Perl#20742
pjacklam
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May 20, 2023
The code in report_redefined_cv() would check whether the old constant and the new constant were the same SV to avoid warning on duplicate imports of the same constant. Since both gv_setref() and report_redefined_cv() used cv_const_sv() to fetch the constant SV, which returns NULL for an AV based constant sub, the check for the equivalent SV would compare NULL to NULL and report_redefined_cv() would return early. Additional checks were required further down to prevent sv_cmp() being called on AVs. The check for simple SV's allow redefinition of constant subs if the new value string compares the same as the old value. The AV check does not try to allow that. Fixed Perl#20742
khwilliamson
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Jul 10, 2023
The code in report_redefined_cv() would check whether the old constant and the new constant were the same SV to avoid warning on duplicate imports of the same constant. Since both gv_setref() and report_redefined_cv() used cv_const_sv() to fetch the constant SV, which returns NULL for an AV based constant sub, the check for the equivalent SV would compare NULL to NULL and report_redefined_cv() would return early. Additional checks were required further down to prevent sv_cmp() being called on AVs. The check for simple SV's allow redefinition of constant subs if the new value string compares the same as the old value. The AV check does not try to allow that. Fixed Perl#20742
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Module: constant
Description
Redefining a list constant does not produce a warning.
Steps to Reproduce
This redefinition of a scalar constant warns:
But this redefinition of a list one doesn't:
Expected behavior
I expected to see a warning when redefining the list constant.
Perl configuration
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