dvc metrics show doesn't output anything when called from a subdirectory of the repository

[ldelphinpoulat]

Bug Report

dvc metrics show doesn't output anything when called from a subdirectory of the repository.

Description

When the pipeline described in dvc.yaml is stored in a subdirectory e.g. pipeline of the repository and it contains a stage that produces a metric file e.g. metric.json within this same directory, running dvc metrics show within this directory doesn't ouptut anything. When calling dvc metrics show metric.json, the displayed path for the metric is not correct. Calling dvc metric show from the root of the repository seems to be ok. The issue was already looked at by @pared who provided the simplified script to reproduce the behavior.

Reproduce

Run the following script:

#!/bin/bash

set -exu

wsp=test_wspace
rep=test_repo

rm -rf $wsp && mkdir $wsp && pushd $wsp
main=$(pwd)

mkdir $rep && pushd $rep

git init
dvc init

echo '{"metric_val": 1}' > data.json
dvc add data.json

mkdir pipeline
pushd pipeline

dvc run -d ../data.json -m metric.json -n train cp ../data.json metric.json

git add -A
git commit -am "initial"

echo "dvc metrics show in repo subdirectory"
dvc metrics show -v

echo "dvc metrics show metric.json"
dvc metrics show -v metric.json

popd
echo "dvc metrics show in repo root"
dvc metrics show -v

Expected

The first call to dvc metrics show (in the pipeline subdirectory) doesn't output anything.
The call to to dvc metrics show metric.json (in the pipeline subdirectory) outputs:

Path            metric_val
../metric.json  1

The second call to dvc metrics show (in the repo root) outputs:

Path                  metric_val
pipeline/metric.json  1

which is ok.
'-v' option only adds lines of the following form:

2022-07-15 14:16:08,463 DEBUG: Analytics is enabled.
2022-07-15 14:16:08,464 DEBUG: Trying to spawn '['daemon', '-q', 'analytics', '/tmp/tmpiwodbd2a']'
2022-07-15 14:16:08,465 DEBUG: Spawned '['daemon', '-q', 'analytics', '/tmp/tmpiwodbd2a']'

Environment information

dvc was installed from repository on an Ubuntu 20.04 (WSL). I also have the same behavior on dvc installed with pip, within a conda environment on Ubuntu 20.04.
Output of dvc doctor:

$ dvc doctor

DVC version: 2.11.0 (deb)
---------------------------------
Platform: Python 3.8.3 on Linux-5.10.102.1-microsoft-standard-WSL2-x86_64-with-glibc2.14
Supports:
        azure (adlfs = 2022.4.0, knack = 0.9.0, azure-identity = 1.10.0),
        gdrive (pydrive2 = 1.10.1),
        gs (gcsfs = 2022.5.0),
        hdfs (fsspec = 2022.5.0, pyarrow = 8.0.0),
        webhdfs (fsspec = 2022.5.0),
        http (aiohttp = 3.8.1, aiohttp-retry = 2.4.6),
        https (aiohttp = 3.8.1, aiohttp-retry = 2.4.6),
        s3 (s3fs = 2022.5.0, boto3 = 1.21.21),
        ssh (sshfs = 2022.6.0),
        oss (ossfs = 2021.8.0),
        webdav (webdav4 = 0.9.7),
        webdavs (webdav4 = 0.9.7)

Additional Information (if any):

[pared]

My brief research seems to point into dvc/repo/metrics/show.py::_to_fs_paths as a culprit.

[pared]

@ldelphinpoulat This should be fixed for dvc>=2.21.0.