_sre.template crashes iftemplate argument contains group index that is negative or not anint instance.
Examples:

>>>import_sre>>>_sre.template("", ["",-1,""])Segmentationfault (coredumped)

>>>_sre.template("", ["", (),""])Segmentationfault (coredumped)

In_sre_template_impl part ofself->items remains uninitialized if call toPyLong_AsSsize_t returns negative value or fails with exception. Then attempt to clearself->items[i].literal intemplate_clear leads to dereferencing of uninitialized pointer.

Not sure if this worth fixing, since_sre.template is an internal implementation detail that is used only in_compile_template function, where it accepts only (I guess) correct templates created in_parser.parse_template function, and additional checks/initialization can affect its performance. But I'll submit a PR anyway.

Linked PRs

• gh-106524: Zero template items before initializing them in_sre.template #106525
• [3.12] gh-106524: Fix a crash in _sre.template() (GH-106525) #106544