[Bug rust/23871] New: better support for slices

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=23871

Bug ID: 23871
Summary: better support for slices
Product: gdb
Version: HEAD
Status: NEW
Severity: normal
Priority: P2
Component: rust
Assignee: unassigned at sourceware dot org
Reporter: tromey at sourceware dot org
Target Milestone: ---

Compile & debug this program:

pub fn main() {
let x = &[1, 2, 3, 4, 5];
let y = &x[..];
let z = 7;
}


First, 'x' is not recognized as a slice:

(gdb) p x
$1 = (i32 (*)[5]) 0x555555577b40

The DWARF says it is a pointer to an array:

<1><30d>: Abbrev Number: 6 (DW_TAG_pointer_type)
<30e> DW_AT_type : <0x316>
<312> DW_AT_name : (indirect string, offset: 0x2bd): &[i32; 5]
<1><316>: Abbrev Number: 7 (DW_TAG_array_type)
<317> DW_AT_type : <0x323>
<2><31b>: Abbrev Number: 8 (DW_TAG_subrange_type)
<31c> DW_AT_type : <0x32a>
<320> DW_AT_lower_bound : 0
<321> DW_AT_count : 5
<2><322>: Abbrev Number: 0


... maybe this should be fixed in rustc, but maybe in gdb.


Second, rust-gdb's pretty-printer shows this for 'y':

(gdb) p y
$2 = &[i32](len: 5) = {1, 2, 3, 4, 5}


But gdb shows:

(gdb) p/r y
$3 = &[i32] {
data_ptr: 0x555555577b40,
length: 5
}


It might make sense to have the built-in printer work
more like rust-gdb's.