bazel test --run_under with gdb not working?

[glin...@gmail.com]

I'm trying to run a cc_test with "bazel test --run_under='gdb --args' :my_test", and it always reports success, without starting up gdb. Is there some magic to get this to work? I've tried --run_under='gdb' alone as well, and same result.

Thanks!

[Brian Silverman]

Bazel doesn't connect stdin through to the terminal with `bazel test`, which looks like it makes gdb just exit immediately. You can look at the test output at bazel-testlogs/package/my_test/test.log to confirm. `bazel run --run_under=gdb` should do what you want, although it won't set up the test-specific environment variables (like TEST_TMPDIR) automatically.

On Thu, Jan 21, 2016 at 6:09 PM, <glin...@gmail.com> wrote:

I'm trying to run a cc_test with "bazel test --run_under='gdb --args' :my_test", and it always reports success, without starting up gdb.  Is there some magic to get this to work?  I've tried --run_under='gdb' alone as well, and same result.

Thanks!

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[glin...@gmail.com]

Ok, thanks Brian! This would definitely be a useful feature, maybe a pull request incoming :).

[glin...@gmail.com]

It looks like gdb is not happy under bazel run either. gdb exits instantly again, this time it prints the startup info at least though. ie. "bazel run --run_under='gdb --args' :my_test" gives

INFO: Running command line: /bin/bash -c 'gdb --args bazel-bin/my_test '
GNU gdb (Ubuntu 7.7.1-0ubuntu5~14.04.2) 7.7.1
Copyright (C) 2014 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-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://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 <...>(no debugging symbols found)...done.
(gdb) quit

On Thursday, January 21, 2016 at 6:32:16 PM UTC-8, Brian Silverman wrote:

[Austin Schuh]

GDB may be looking for a pty.  Shot in the dark.

To view this discussion on the web visit https://groups.google.com/d/msgid/bazel-discuss/0dfebd9c-2ff3-4a27-93db-afecc2253934%40googlegroups.com.

[rodr...@google.com]

On Friday, January 22, 2016 at 3:09:37 AM UTC+1, glin...@gmail.com wrote:
> I'm trying to run a cc_test with "bazel test --run_under='gdb --args' :my_test", and it always reports success, without starting up gdb. Is there some magic to get this to work? I've tried --run_under='gdb' alone as well, and same result.
>
> Thanks!

Resurrecting this thread to share a trick I found, --run_under="gdbserver :2345", eg:

bazel test -c gdb --cache_test_results=no --run_under='gdbserver :2345' :my_test
# in another terminal:
gdb -ex "target remote :2345"

[Brandon Adams]

On Friday, January 22, 2016 at 10:44:42 AM UTC-6, glin...@gmail.com wrote:

It looks like gdb is not happy under bazel run either.  gdb exits instantly again, this time it prints the startup info at least though.  ie. "bazel run --run_under='gdb --args' :my_test" gives

Besides gdbserver, you can use a wrapper script that redirects stdin/stdout/stderr. I have a wrapper on my path that looks like this (replace $$$WORKSPACENAME$$$ with the name of your workspace):

```bash

#!/usr/bin/env bash

# We need to run gdb ... < /dev/tty in order to get stdin as an interactive process under bazel run's --run_under

# Additionally, we get dropped into the runfiles of the target directory. This is suboptimal, so we use sed to find

# the execroot, and tell gdb to cd there so we get both our source files and our external sources.

gdb -ex "directory $(pwd | sed -E 's|(.*/execroot/$$$WORKSPACENAME$$$/).*|\1|')" "$@" < /dev/tty > /dev/tty 2>/dev/tty

 
```

I then say `bazel run --run_under=gdb_wrapper.sh //my:target`

This seems to work okay.

Alternately, you might want to setup a gdbinit to fix your directory instead, so that it works under CLion/gdbserver, etc.

Good luck,

- Brandon