Add a flag to have `uv tool upgrade` upgrade the python version to a supported version

[danielhoherd]

Summary

When attempting to upgrade a tool to a version that has a python version requirement newer than the python version that is installed in the venv, uv aborts with an error, and specifying a python version seems to be the only way to perform the upgrade without doing a complete install.

I would like to see a flag that would determine the required python version and upgrade it in the venv. EG: uv tool upgrade --upgrade-python foo

Example

$ uv tool upgrade dho-tools
error: Failed to upgrade dho-tools
  Caused by: Because the current Python version (3.13) does not satisfy Python>=3.14 and dho-tools==0.6.1 depends on Python>=3.14, we can conclude that dho-tools==0.6.1 cannot be used.
             And because only dho-tools==0.6.1 is available and you require dho-tools, we can conclude that your requirements are unsatisfiable.

The way out of this is to run uv tool upgrade -p 3.14.3 dho-tools. Even though uv knows what the minimum version is, there is no way to say "yeah, use a compatible python version." The user must be specific about what version to use, which makes scripting these upgrades more difficult.

Reproduction

#!/usr/bin/env bash

set -x
rm -rf uv-test-18083
set -e
mkdir uv-test-18083
cd uv-test-18083
uv init -p 3.13 --package
uv tool install -p 3.13 .
sed -i 's/3.13/3.14/' pyproject.toml  # requires GNU sed
uv tool upgrade uv-test-18083

To clean up, run uv tool uninstall uv-test-18083

The output is:

$ ./uv-test-18083.sh
+ rm -rf uv-test-18083
+ set -e
+ mkdir uv-test-18083
+ cd uv-test-18083
+ uv init -p 3.13 --package
Initialized project `uv-test-18083`
+ uv tool install -p 3.13 .
Resolved 1 package in 2ms
      Built uv-test-18083 @ file:///tmp/tmp.OInvrMGEsn/uv-test-18083
Prepared 1 package in 6ms
Installed 1 package in 1ms
 + uv-test-18083==0.1.0 (from file:///tmp/tmp.OInvrMGEsn/uv-test-18083)
Installed 1 executable: uv-test-18083
+ sed -i s/3.13/3.14/ pyproject.toml
+ uv tool upgrade uv-test-18083
error: Failed to upgrade uv-test-18083
  Caused by: Because the current Python version (3.13.5) does not satisfy Python>=3.14 and uv-test-18083==0.1.0 depends on Python>=3.14, we can conclude that uv-test-18083==0.1.0 cannot be used.
             And because only uv-test-18083==0.1.0 is available and you require uv-test-18083, we can conclude that your requirements are unsatisfiable.

[powercoconola]

Just curious, what happens when you run uv tool install dho-tools@latest --force?

Or uv tool install dho-tools@latest --reinstall --force?

[danielhoherd]

@powercoconola I'm installing from a locally cloned git repo, and there is no @latest tag, so that does not work:

$ uv tool install /tmp/dho-tools@latest --force
error: Distribution not found at: file:///tmp/dho-tools@latest

Testing your second command shows:

$ uv tool install "$PWD/dho-tools" --reinstall --force
  × No solution found when resolving dependencies:
  ╰─▶ Because the current Python version (3.13) does not satisfy Python>=3.14 and dho-tools==0.6.2 depends on Python>=3.14, we can conclude
      that dho-tools==0.6.2 cannot be used.
      And because only dho-tools==0.6.2 is available and you require dho-tools, we can conclude that your requirements are unsatisfiable.

[powercoconola]

Do you have the UV_PYTHON environment variable set?

[danielhoherd]

No.

[konstin]

The problem is that we decide the Python version before we decide tool version, which needs to be inverted to make this work properly.