uv sync fails when interpreter is not named python[3]

[zanieb]

See discussion in #4277

Instead of only searching for, e.g., python3.12 executables when Python 3.12 is requested (and not during the default search), we should use which_re (or a manually implemented which) to find all possible Python executables then filter them to meet the version request (if necessary).

[zanieb]

See python_executables_from_search_path for the current implementation.

[konstin]

The current behaviour is a problem when using pyenv: When using uv sync, uv fails to find a python interpreter even if it exists if the default python/python3 are incompatible.

For example with both requires-python = "==3.10.*" requires-python = ">=3.10", where the default python/python3 are any other version, say 3.9:

This fails:

uv sync --python-preference only-system

This passes:

uv sync --python-preference only-system -p 3.10

uv should find the python 3.10 interpreter in either case.

Reproduction

FROM ubuntu
ENV DEBIAN_FRONTEND=noninteractive
RUN apt update
RUN apt install -yy build-essential libssl-dev zlib1g-dev \
    libbz2-dev libreadline-dev libsqlite3-dev curl git \
    libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev
RUN curl https://pyenv.run | bash
ENV PATH="/root/.pyenv/bin:$PATH"
RUN CONFIGURE_OPTS="--enable-optimizations" pyenv install 3.8.12 3.8.18
RUN CONFIGURE_OPTS="--enable-optimizations" pyenv install 3.9.18
RUN CONFIGURE_OPTS="--enable-optimizations" pyenv install 3.10.13
RUN CONFIGURE_OPTS="--enable-optimizations" pyenv install 3.11.7
RUN CONFIGURE_OPTS="--enable-optimizations" pyenv install 3.12.1
RUN pyenv global 3.8.12 3.8.18 3.9.18 3.10.13 3.11.7 3.12.1
# https://github.com/pyenv/pyenv#set-up-your-shell-environment-for-pyenv
RUN echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.bashrc \
    && echo 'command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.bashrc \
    && echo 'eval "$(pyenv init -)"' >> ~/.bashrc

Create a dummy pyproject.toml, any requires-python that mismatches the default active python will do:

[project]
name = "a"
version = "0.1.0"
requires-python = "==3.10.*"
dependencies = ["tqdm"]

Compile uv:

cargo build --release --target x86_64-unknown-linux-musl

Start the docker container, mount the uv dir to /io and run commands with

/io/target/x86_64-unknown-linux-musl/release/uv sync

[charliermarsh]

I think this needs an owner. @konstin?

[konstin]

Will do