[Bug backtrace/29298] New: Internal error when debugging Rust programs

[Bug backtrace/29298] New: Internal error when debugging Rust programs

[nils at os dot inf.tu-dresden.de]

https://sourceware.org/bugzilla/show_bug.cgi?id=29298

            Bug ID: 29298
           Summary: Internal error when debugging Rust programs
           Product: gdb
           Version: 12.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: backtrace
          Assignee: unassigned at sourceware dot org
          Reporter: nils at os dot inf.tu-dresden.de
  Target Milestone: ---

With some Rust programs, generating a backtrace leads to an internal error in
GDB:

$ gdb target/debug/test
GNU gdb (GDB) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from target/debug/test...
warning: Missing auto-load script at offset 0 in section .debug_gdb_scripts
of file /home/hrniels/test/foo/target/debug/test.
Use `info auto-load python-scripts [REGEXP]' to list them.
(gdb) b main
Breakpoint 1 at 0x9530
(gdb) run
Starting program: /home/hrniels/test/foo/target/debug/test 

This GDB supports auto-downloading debuginfo from the following URLs:
https://debuginfod.archlinux.org
Enable debuginfod for this session? (y or [n]) n
Debuginfod has been disabled.
To make this setting permanent, add 'set debuginfod enabled off' to .gdbinit.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".

Breakpoint 1, 0x000055555555d530 in main ()
(gdb) bt
../../gdb/frame.c:2434: internal-error: inside_main_func: Assertion `block !=
nullptr' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
----- Backtrace -----
0x563c6fccbb6b ???
0x563c70009d44 ???
0x563c700ccce3 ???
0x563c6fde3fa2 ???
0x563c6fef057d ???
0x563c6fef283d ???
0x563c6fdc2615 ???
0x563c6ff7ace7 ???
0x563c6fd01d74 ???
0x563c6ffd1812 ???
0x563c6fdc7bfc ???
0x563c6fdc7c9d ???
0x563c6fdb901f ???
0x7fcb3b36c9df ???
0x563c6fdbca3b ???
0x563c6fdbcc23 ???
0x563c6fdc7b2f ???
0x563c700cd955 ???
0x563c700cdd39 ???
0x563c6fe8bd24 ???
0x563c6fc37c04 ???
0x7fcb3a22928f ???
0x7fcb3a229349 ???
0x563c6fc3e1e4 ???
0xffffffffffffffff ???
---------------------
../../gdb/frame.c:2434: internal-error: inside_main_func: Assertion `block !=
nullptr' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) n


I'm not exactly sure what the cause is, but the following Rust program can
(hopefully) be used to reproduce the behavior:

fn main() {
    println!("{}", std::env::var("RUST_LOG").unwrap_or_else(|_|
"error".to_string()));
}

Note also that the problem goes away if I use `unwrap_or("error".to_string())`
instead of `unwrap_or_else(|_| "error".to_string())`. So, maybe the closure
plays a role here?

In case it matters, I'm using Rust 1.61.0 (a028ae4 2022-04-29).

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[Bug backtrace/29298] Internal error when debugging Rust programs

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29298

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at sourceware dot org

--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
I couldn't make it fail here.  I tried 1.61 and 1.62.

It would be easy to patch around this assert, but I think
we'd rather not do that without understanding the problem first.

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[Bug backtrace/29298] Internal error when debugging Rust programs

[nils at os dot inf.tu-dresden.de]

https://sourceware.org/bugzilla/show_bug.cgi?id=29298

--- Comment #2 from Nils Asmussen <nils at os dot inf.tu-dresden.de> ---
There was indeed one thing missing as I just noticed when trying it on another
system. Sorry for that.

I have the following line in my ~/.gdbinit:

set demangle-style gnu-v3

Without this line, the problem disappears.

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[Bug backtrace/29298] Internal error when debugging Rust programs

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29298

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-08-05

--- Comment #3 from Tom Tromey <tromey at sourceware dot org> ---
I was able to reproduce it by changing that setting.

I tend to think the "demangle-style" should not be settable.
IMO it is a relic of the pre-v3 days, when maybe setting it
by hand made sense .... but that doesn't really make sense any
more, and the setting doesn't really do anything useful.

Meanwhile, remove that from your .gdbinit and everything should be fine.

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[Bug backtrace/29298] Internal error when debugging Rust programs

[e11911636 at student dot tuwien.ac.at]

https://sourceware.org/bugzilla/show_bug.cgi?id=29298

Michael Schmidt <e11911636 at student dot tuwien.ac.at> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |e11911636 at student dot tuwien.ac
                   |                            |.at

--- Comment #4 from Michael Schmidt <e11911636 at student dot tuwien.ac.at> ---
I can reproduce this without setting demangle-style (rustc 1.67.0 (fc594f156
2023-01-24)), same conditions as with Nils. I bisected gdb and it seems this
was introduced in 7f4307436f.

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[Bug backtrace/29298] Internal error when debugging Rust programs

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29298

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING

--- Comment #5 from Tom Tromey <tromey at sourceware dot org> ---
(In reply to Michael Schmidt from comment #4)
> I can reproduce this without setting demangle-style (rustc 1.67.0 (fc594f156
> 2023-01-24)), same conditions as with Nils. I bisected gdb and it seems this
> was introduced in 7f4307436f.

Maybe this is a dup of bug#30158 then.
Can you try a gdb from git, either from the 13 branch or from master?

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[Bug backtrace/29298] Internal error when debugging Rust programs

[e11911636 at student dot tuwien.ac.at]

https://sourceware.org/bugzilla/show_bug.cgi?id=29298

--- Comment #6 from Michael Schmidt <e11911636 at student dot tuwien.ac.at> ---
(In reply to Tom Tromey from comment #5)
> (In reply to Michael Schmidt from comment #4)
> > I can reproduce this without setting demangle-style (rustc 1.67.0 (fc594f156
> > 2023-01-24)), same conditions as with Nils. I bisected gdb and it seems this
> > was introduced in 7f4307436f.
> 
> Maybe this is a dup of bug#30158 then.
> Can you try a gdb from git, either from the 13 branch or from master?

Indeed, I tested bf3f6c02d7 (master) and 8067be0fc6 (gdb-13-branch) and both
work fine.

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[Bug backtrace/29298] Internal error when debugging Rust programs

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29298

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #7 from Tom Tromey <tromey at sourceware dot org> ---
Thanks, I'm going to close it then.

*** This bug has been marked as a duplicate of bug 30158 ***

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