Unable to print static variables from a module in GDB

help
1

I have the following project:

// main.rs
mod other;

#[derive(Debug)]
pub(crate) struct MainStruct { 
    number: usize,
}
pub(crate) static MY_MAIN: MainStruct = MainStruct { number: 123 };

fn main() {
    loop {
        ::std::thread::sleep_ms(1000);
        println!("{:?} {:?}", MY_MAIN, other::MY_STATIC);
    }
}

// other.rs
#[derive(Debug)]
pub(crate) struct MyStruct {
    number: usize,
}
pub(crate) static MY_STATIC: MyStruct = MyStruct { number: 1337 };

I run the program, and connect to it with gdb -p (PID). I want to print out the statics:

(gdb) p gdb_test<TAB>
gdb_test                    gdb_test::main              gdb_test::other::MyStruct   
gdb_test::MY_MAIN           gdb_test::other             gdb_test::other::{{impl}}   
gdb_test::MainStruct        gdb_test::other::MY_STATIC  gdb_test::{{impl}}          
(gdb) p gdb_test::MY_MAIN
$1 = {number = 123}
(gdb) p gdb_test::other::MY_STATIC
No type "other" within class or namespace "gdb_test".

That is, I'm unable to print out statics that are not in the top level.

The version of gdb I'm running is

~/t/gdb-test> gdb -v
GNU gdb (Ubuntu 8.1-0ubuntu3) 8.1.0.20180409-git

Running rust-gdb does not help.

I'm sure I've been able to do this previously (a few months ago).

2

If I'm not mistaken, since your module isn't pub mod, the static is assumed to be never reachable from outside the crate. Does pub mod make it visible?

3

No, it doesn't seem to help any. I figured it wasn't a problem of visibility, since gdb_test::other::MY_STATIC comes up in the tab autocomplete, so presumably the debug info is somewhere in the executable.

4

debuginfo: Generate debugging information for global variables. · Issue #9227 · rust-lang/rust · GitHub suggests you may need to enclose the path in a single quote, i.e.:

p 'gdb_test::other::MY_STATIC'

That issue is a few years old, so I'm not sure if anything's changed in this area but worth a try.

2 Likes
5

This does indeed work! Thank you.