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From: "tromey at sourceware dot org" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug rust/30330] GDB 13.1 no longer prints length of Rust slice
 wrappers
Date: Fri, 28 Jul 2023 21:31:45 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D30330

--- Comment #8 from Tom Tromey <tromey at sourceware dot org> ---
Unsized types doc'd here:
https://doc.rust-lang.org/book/ch19-04-advanced-types.html#dynamically-size=
d-types-and-the-sized-trait

I don't know why I keep not understanding this but I think I
finally figured it out.

(gdb) ptype a
type =3D struct &prog::Foo<[u8]> {
    struct prog::Foo<[u8]> *data_ptr;
    usize length;
}

So here, gdb should change the type of 'data_ptr'
to 'struct prog::Foo<[u8; ...length...]> *'

This can't readily be expressed in DWARF I think.
But gdb can apply the change by itself.

So then all that remains is fixing up the instance
not to use 'u8' (but rather 'u8[]') as the type of the
"VLA" part.

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