bug#79483: Segmentation fault: set-car! in compiled code

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<[email protected]> writes:

> On Mon, Sep 22, 2025 at 12:50:57AM +0300, var-vniiaes--- via Bug reports =
for GUILE, GNU's Ubiquitous Extension Language wrote:
>>=20
>> Hello,
>> =C2=A0
>> Execution of =C2=A0 (set-car! '(0) 1) =C2=A0 *in compiled code* =C2=A0le=
ads to segfault:
>
> First of all: you shouldn't be doing that :)
>
> You are mutating a constant. I don't know what the Scheme specification s=
ays
> to it (if at all).

=2D-8<---------------cut here---------------start------------->8---
As noted in section 3.4, it is an error to attempt to alter
a constant (i.e. the value of a literal expression) using a
mutation procedure like set-car! or string-set!
=2D-8<---------------cut here---------------end--------------->8---

> The other question is whether Guile should/could catch that and signal an
> error instead.

I believe it should not.  Memory-safe languages (and, Guile is supposed
to be one) should never segfault but instead terminate with a sensible
error.  I realize that 1.3.2 allows to "fail catastrophically", which
segfault probably qualifies as, but I believe we should do better.

Tomas

=2D-=20
There are only two hard things in Computer Science:
cache invalidation, naming things and off-by-one errors.

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