Segfault when inheriting from class in unit syntax #20890
Comments
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For what it’s worth, this seems to work fine: {
class A;
}
class B :isa(A) { } |
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@leonerd, can you take a look at this problem re |
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The problem is the class_initfields_cv pointer (which creates the sub that initializes the class fields) isn't created until the end of scope, and in the failing case that is after the In the non-crashing case, the {} around the I'm not sure how this is intended to work, if I do a "statement" package, a block package restores the current class: but if we do that with class, as with the failing code, the documentation says the class is closed once
what should the current class/package be after the closing brace of I'd be inclined to simply disallow the statement form. Backtrace with debug info: |
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Nice find. FWIW, I think the statement form is important to have in Perl. Consistency with class A;
class B {}class A {
class B {}
}Which means it should perhaps be a syntax error for B to inherit from A here because the declaration of A is not yet complete by the time the It turns out the second form causes what I expect is the exact same issue without (Although I wonder if allowing |
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For what it's worth, someone asked a related question on Reddit and I provided an answer, linking to this thread. |
Description
A class declared in the “unit” (or “statement”) syntax – i. e. not with a block – cannot be used as the superclass of another class. A segmentation fault occurs when this is attempted. This happens with v5.37.9 as well as blead at 49830b9 (HEAD at time of this writing). The following combination triggers the bug:
class A; class B :isa(A) { }(The diagnostics generated by my OS include a stack trace and are appended at the end of this report.)
Steps to Reproduce
perl -Mfeature=class -e 'class A; class B :isa(A) {}'Expected behaviour
Clean exit.
Perl configuration
Diagnostic report
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