Rename gourgeist to uv-virtualenv (#2118)

As agreed on Discord!

crates/uv-virtualenv/Cargo.toml

@@ -0,0 +1,44 @@
+[package]
+name = "uv-virtualenv"
+version = "0.0.4"
+publish = false
+description = "virtualenv creation implemented in rust"
+keywords = ["virtualenv", "venv", "python"]
+
+edition = { workspace = true }
+rust-version = { workspace = true }
+homepage = { workspace = true }
+documentation = { workspace = true }
+repository = { workspace = true }
+authors = { workspace = true }
+license = { workspace = true }
+
+[[bin]]
+name = "uv-virtualenv"
+required-features = ["cli"]
+
+[lints]
+workspace = true
+
+[dependencies]
+platform-host = { path = "../platform-host" }
+uv-cache = { path = "../uv-cache" }
+uv-fs = { path = "../uv-fs" }
+uv-interpreter = { path = "../uv-interpreter" }
+
+anstream = { workspace = true }
+cachedir = { workspace = true }
+camino = { workspace = true }
+clap = { workspace = true, features = ["derive"], optional = true }
+directories = { workspace = true }
+fs-err = { workspace = true }
+serde = { workspace = true }
+serde_json = { workspace = true }
+tempfile = { workspace = true }
+thiserror = { workspace = true }
+tracing = { workspace = true }
+tracing-subscriber = { workspace = true, optional = true }
+which = { workspace = true }
+
+[features]
+cli = ["clap", "tracing-subscriber"]

crates/uv-virtualenv/README.md

@@ -0,0 +1,3 @@
+# uv-virtualenv
+
+`uv-virtualenv` is a rust library to create Python virtual environments. It also has a CLI.

crates/uv-virtualenv/src/_virtualenv.py

@@ -0,0 +1,103 @@
+"""Patches that are applied at runtime to the virtual environment."""
+
+from __future__ import annotations
+
+import os
+import sys
+
+VIRTUALENV_PATCH_FILE = os.path.join(__file__)
+
+
+def patch_dist(dist):
+    """
+    Distutils allows user to configure some arguments via a configuration file:
+    https://docs.python.org/3/install/index.html#distutils-configuration-files.
+
+    Some of this arguments though don't make sense in context of the virtual environment files, let's fix them up.
+    """  # noqa: D205
+    # we cannot allow some install config as that would get packages installed outside of the virtual environment
+    old_parse_config_files = dist.Distribution.parse_config_files
+
+    def parse_config_files(self, *args, **kwargs):
+        result = old_parse_config_files(self, *args, **kwargs)
+        install = self.get_option_dict("install")
+
+        if "prefix" in install:  # the prefix governs where to install the libraries
+            install["prefix"] = VIRTUALENV_PATCH_FILE, os.path.abspath(sys.prefix)
+        for base in ("purelib", "platlib", "headers", "scripts", "data"):
+            key = f"install_{base}"
+            if key in install:  # do not allow global configs to hijack venv paths
+                install.pop(key, None)
+        return result
+
+    dist.Distribution.parse_config_files = parse_config_files
+
+
+# Import hook that patches some modules to ignore configuration values that break package installation in case
+# of virtual environments.
+_DISTUTILS_PATCH = "distutils.dist", "setuptools.dist"
+# https://docs.python.org/3/library/importlib.html#setting-up-an-importer
+
+
+class _Finder:
+    """A meta path finder that allows patching the imported distutils modules."""
+
+    fullname = None
+
+    # lock[0] is threading.Lock(), but initialized lazily to avoid importing threading very early at startup,
+    # because there are gevent-based applications that need to be first to import threading by themselves.
+    # See https://github.com/pypa/virtualenv/issues/1895 for details.
+    lock = []  # noqa: RUF012
+
+    def find_spec(self, fullname, path, target=None):  # noqa: ARG002
+        if fullname in _DISTUTILS_PATCH and self.fullname is None:
+            # initialize lock[0] lazily
+            if len(self.lock) == 0:
+                import threading
+
+                lock = threading.Lock()
+                # there is possibility that two threads T1 and T2 are simultaneously running into find_spec,
+                # observing .lock as empty, and further going into hereby initialization. However due to the GIL,
+                # list.append() operation is atomic and this way only one of the threads will "win" to put the lock
+                # - that every thread will use - into .lock[0].
+                # https://docs.python.org/3/faq/library.html#what-kinds-of-global-value-mutation-are-thread-safe
+                self.lock.append(lock)
+
+            from functools import partial
+            from importlib.util import find_spec
+
+            with self.lock[0]:
+                self.fullname = fullname
+                try:
+                    spec = find_spec(fullname, path)
+                    if spec is not None:
+                        # https://www.python.org/dev/peps/pep-0451/#how-loading-will-work
+                        is_new_api = hasattr(spec.loader, "exec_module")
+                        func_name = "exec_module" if is_new_api else "load_module"
+                        old = getattr(spec.loader, func_name)
+                        func = self.exec_module if is_new_api else self.load_module
+                        if old is not func:
+                            try:  # noqa: SIM105
+                                setattr(spec.loader, func_name, partial(func, old))
+                            except AttributeError:
+                                pass  # C-Extension loaders are r/o such as zipimporter with <3.7
+                        return spec
+                finally:
+                    self.fullname = None
+        return None
+
+    @staticmethod
+    def exec_module(old, module):
+        old(module)
+        if module.__name__ in _DISTUTILS_PATCH:
+            patch_dist(module)
+
+    @staticmethod
+    def load_module(old, name):
+        module = old(name)
+        if module.__name__ in _DISTUTILS_PATCH:
+            patch_dist(module)
+        return module
+
+
+sys.meta_path.insert(0, _Finder())

crates/uv-virtualenv/src/activate

@@ -0,0 +1,87 @@
+# This file must be used with "source bin/activate" *from bash*
+# you cannot run it directly
+
+
+if [ "${BASH_SOURCE-}" = "$0" ]; then
+    echo "You must source this script: \$ source $0" >&2
+    exit 33
+fi
+
+deactivate () {
+    unset -f pydoc >/dev/null 2>&1 || true
+
+    # reset old environment variables
+    # ! [ -z ${VAR+_} ] returns true if VAR is declared at all
+    if ! [ -z "${_OLD_VIRTUAL_PATH:+_}" ] ; then
+        PATH="$_OLD_VIRTUAL_PATH"
+        export PATH
+        unset _OLD_VIRTUAL_PATH
+    fi
+    if ! [ -z "${_OLD_VIRTUAL_PYTHONHOME+_}" ] ; then
+        PYTHONHOME="$_OLD_VIRTUAL_PYTHONHOME"
+        export PYTHONHOME
+        unset _OLD_VIRTUAL_PYTHONHOME
+    fi
+
+    # The hash command must be called to get it to forget past
+    # commands. Without forgetting past commands the $PATH changes
+    # we made may not be respected
+    hash -r 2>/dev/null
+
+    if ! [ -z "${_OLD_VIRTUAL_PS1+_}" ] ; then
+        PS1="$_OLD_VIRTUAL_PS1"
+        export PS1
+        unset _OLD_VIRTUAL_PS1
+    fi
+
+    unset VIRTUAL_ENV
+    unset VIRTUAL_ENV_PROMPT
+    if [ ! "${1-}" = "nondestructive" ] ; then
+    # Self destruct!
+        unset -f deactivate
+    fi
+}
+
+# unset irrelevant variables
+deactivate nondestructive
+
+VIRTUAL_ENV='{{ VIRTUAL_ENV_TEMPLATE_STRING }}'
+if ([ "$OSTYPE" = "cygwin" ] || [ "$OSTYPE" = "msys" ]) && $(command -v cygpath &> /dev/null) ; then
+    VIRTUAL_ENV=$(cygpath -u "$VIRTUAL_ENV")
+fi
+export VIRTUAL_ENV
+
+_OLD_VIRTUAL_PATH="$PATH"
+PATH="$VIRTUAL_ENV/bin:$PATH"
+export PATH
+
+if [ "x" != x ] ; then
+    VIRTUAL_ENV_PROMPT=""
+else
+    VIRTUAL_ENV_PROMPT=$(basename "$VIRTUAL_ENV")
+fi
+export VIRTUAL_ENV_PROMPT
+
+# unset PYTHONHOME if set
+if ! [ -z "${PYTHONHOME+_}" ] ; then
+    _OLD_VIRTUAL_PYTHONHOME="$PYTHONHOME"
+    unset PYTHONHOME
+fi
+
+if [ -z "${VIRTUAL_ENV_DISABLE_PROMPT-}" ] ; then
+    _OLD_VIRTUAL_PS1="${PS1-}"
+    PS1="(${VIRTUAL_ENV_PROMPT}) ${PS1-}"
+    export PS1
+fi
+
+# Make sure to unalias pydoc if it's already there
+alias pydoc 2>/dev/null >/dev/null && unalias pydoc || true
+
+pydoc () {
+    python -m pydoc "$@"
+}
+
+# The hash command must be called to get it to forget past
+# commands. Without forgetting past commands the $PATH changes
+# we made may not be respected
+hash -r 2>/dev/null

crates/uv-virtualenv/src/activator/.gitattributes

@@ -0,0 +1 @@
+*.bat text eol=crlf

crates/uv-virtualenv/src/activator/activate

@@ -0,0 +1,108 @@
+# Copyright (c) 2020-202x The virtualenv developers
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+# This file must be used with "source bin/activate" *from bash*
+# you cannot run it directly
+
+
+if [ "${BASH_SOURCE-}" = "$0" ]; then
+    echo "You must source this script: \$ source $0" >&2
+    exit 33
+fi
+
+deactivate () {
+    unset -f pydoc >/dev/null 2>&1 || true
+
+    # reset old environment variables
+    # ! [ -z ${VAR+_} ] returns true if VAR is declared at all
+    if ! [ -z "${_OLD_VIRTUAL_PATH:+_}" ] ; then
+        PATH="$_OLD_VIRTUAL_PATH"
+        export PATH
+        unset _OLD_VIRTUAL_PATH
+    fi
+    if ! [ -z "${_OLD_VIRTUAL_PYTHONHOME+_}" ] ; then
+        PYTHONHOME="$_OLD_VIRTUAL_PYTHONHOME"
+        export PYTHONHOME
+        unset _OLD_VIRTUAL_PYTHONHOME
+    fi
+
+    # The hash command must be called to get it to forget past
+    # commands. Without forgetting past commands the $PATH changes
+    # we made may not be respected
+    hash -r 2>/dev/null
+
+    if ! [ -z "${_OLD_VIRTUAL_PS1+_}" ] ; then
+        PS1="$_OLD_VIRTUAL_PS1"
+        export PS1
+        unset _OLD_VIRTUAL_PS1
+    fi
+
+    unset VIRTUAL_ENV
+    unset VIRTUAL_ENV_PROMPT
+    if [ ! "${1-}" = "nondestructive" ] ; then
+    # Self destruct!
+        unset -f deactivate
+    fi
+}
+
+# unset irrelevant variables
+deactivate nondestructive
+
+VIRTUAL_ENV='{{ VIRTUAL_ENV_DIR }}'
+if ([ "$OSTYPE" = "cygwin" ] || [ "$OSTYPE" = "msys" ]) && $(command -v cygpath &> /dev/null) ; then
+    VIRTUAL_ENV=$(cygpath -u "$VIRTUAL_ENV")
+fi
+export VIRTUAL_ENV
+
+_OLD_VIRTUAL_PATH="$PATH"
+PATH="$VIRTUAL_ENV/{{ BIN_NAME }}:$PATH"
+export PATH
+
+if [ "x{{ VIRTUAL_PROMPT }}" != x ] ; then
+    VIRTUAL_ENV_PROMPT="{{ VIRTUAL_PROMPT }}"
+else
+    VIRTUAL_ENV_PROMPT=$(basename "$VIRTUAL_ENV")
+fi
+export VIRTUAL_ENV_PROMPT
+
+# unset PYTHONHOME if set
+if ! [ -z "${PYTHONHOME+_}" ] ; then
+    _OLD_VIRTUAL_PYTHONHOME="$PYTHONHOME"
+    unset PYTHONHOME
+fi
+
+if [ -z "${VIRTUAL_ENV_DISABLE_PROMPT-}" ] ; then
+    _OLD_VIRTUAL_PS1="${PS1-}"
+    PS1="(${VIRTUAL_ENV_PROMPT}) ${PS1-}"
+    export PS1
+fi
+
+# Make sure to unalias pydoc if it's already there
+alias pydoc 2>/dev/null >/dev/null && unalias pydoc || true
+
+pydoc () {
+    python -m pydoc "$@"
+}
+
+# The hash command must be called to get it to forget past
+# commands. Without forgetting past commands the $PATH changes
+# we made may not be respected
+hash -r 2>/dev/null

crates/uv-virtualenv/src/activator/activate.bat

@@ -0,0 +1,59 @@
+@REM Copyright (c) 2020-202x The virtualenv developers
+@REM
+@REM Permission is hereby granted, free of charge, to any person obtaining
+@REM a copy of this software and associated documentation files (the
+@REM "Software"), to deal in the Software without restriction, including
+@REM without limitation the rights to use, copy, modify, merge, publish,
+@REM distribute, sublicense, and/or sell copies of the Software, and to
+@REM permit persons to whom the Software is furnished to do so, subject to
+@REM the following conditions:
+@REM
+@REM The above copyright notice and this permission notice shall be
+@REM included in all copies or substantial portions of the Software.
+@REM
+@REM THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+@REM EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+@REM MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+@REM NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+@REM LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+@REM OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+@REM WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+@set "VIRTUAL_ENV={{ VIRTUAL_ENV_DIR }}"
+
+@set "VIRTUAL_ENV_PROMPT={{ VIRTUAL_PROMPT }}"
+@if NOT DEFINED VIRTUAL_ENV_PROMPT (
+    @for %%d in ("%VIRTUAL_ENV%") do @set "VIRTUAL_ENV_PROMPT=%%~nxd"
+)
+
+@if defined _OLD_VIRTUAL_PROMPT (
+    @set "PROMPT=%_OLD_VIRTUAL_PROMPT%"
+) else (
+    @if not defined PROMPT (
+        @set "PROMPT=$P$G"
+    )
+    @if not defined VIRTUAL_ENV_DISABLE_PROMPT (
+        @set "_OLD_VIRTUAL_PROMPT=%PROMPT%"
+    )
+)
+@if not defined VIRTUAL_ENV_DISABLE_PROMPT (
+    @set "PROMPT=(%VIRTUAL_ENV_PROMPT%) %PROMPT%"
+)
+
+@REM Don't use () to avoid problems with them in %PATH%
+@if defined _OLD_VIRTUAL_PYTHONHOME @goto ENDIFVHOME
+    @set "_OLD_VIRTUAL_PYTHONHOME=%PYTHONHOME%"
+:ENDIFVHOME
+
+@set PYTHONHOME=
+
+@REM if defined _OLD_VIRTUAL_PATH (
+@if not defined _OLD_VIRTUAL_PATH @goto ENDIFVPATH1
+    @set "PATH=%_OLD_VIRTUAL_PATH%"
+:ENDIFVPATH1
+@REM ) else (
+@if defined _OLD_VIRTUAL_PATH @goto ENDIFVPATH2
+    @set "_OLD_VIRTUAL_PATH=%PATH%"
+:ENDIFVPATH2
+
+@set "PATH=%VIRTUAL_ENV%\{{ BIN_NAME }};%PATH%"

crates/uv-virtualenv/src/activator/activate.csh

@@ -0,0 +1,76 @@
+# Copyright (c) 2020-202x The virtualenv developers
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+# This file must be used with "source bin/activate.csh" *from csh*.
+# You cannot run it directly.
+# Created by Davide Di Blasi <davidedb@gmail.com>.
+
+set newline='\
+'
+
+alias deactivate 'test $?_OLD_VIRTUAL_PATH != 0 && setenv PATH "$_OLD_VIRTUAL_PATH:q" && unset _OLD_VIRTUAL_PATH; rehash; test $?_OLD_VIRTUAL_PROMPT != 0 && set prompt="$_OLD_VIRTUAL_PROMPT:q" && unset _OLD_VIRTUAL_PROMPT; unsetenv VIRTUAL_ENV; unsetenv VIRTUAL_ENV_PROMPT; test "\!:*" != "nondestructive" && unalias deactivate && unalias pydoc'
+
+# Unset irrelevant variables.
+deactivate nondestructive
+
+setenv VIRTUAL_ENV '{{ VIRTUAL_ENV_DIR }}'
+
+set _OLD_VIRTUAL_PATH="$PATH:q"
+setenv PATH "$VIRTUAL_ENV:q/{{ BIN_NAME }}:$PATH:q"
+
+
+
+if ('{{ VIRTUAL_PROMPT }}' != "") then
+    setenv VIRTUAL_ENV_PROMPT '{{ VIRTUAL_PROMPT }}'
+else
+    setenv VIRTUAL_ENV_PROMPT "$VIRTUAL_ENV:t:q"
+endif
+
+if ( $?VIRTUAL_ENV_DISABLE_PROMPT ) then
+    if ( $VIRTUAL_ENV_DISABLE_PROMPT == "" ) then
+        set do_prompt = "1"
+    else
+        set do_prompt = "0"
+    endif
+else
+    set do_prompt = "1"
+endif
+
+if ( $do_prompt == "1" ) then
+    # Could be in a non-interactive environment,
+    # in which case, $prompt is undefined and we wouldn't
+    # care about the prompt anyway.
+    if ( $?prompt ) then
+        set _OLD_VIRTUAL_PROMPT="$prompt:q"
+        if ( "$prompt:q" =~ *"$newline:q"* ) then
+            :
+        else
+            set prompt = '('"$VIRTUAL_ENV_PROMPT:q"') '"$prompt:q"
+        endif
+    endif
+endif
+
+unset env_name
+unset do_prompt
+
+alias pydoc python -m pydoc
+
+rehash

crates/uv-virtualenv/src/activator/activate.fish

@@ -0,0 +1,124 @@
+# Copyright (c) 2020-202x The virtualenv developers
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+# This file must be used using `source bin/activate.fish` *within a running fish ( http://fishshell.com ) session*.
+# Do not run it directly.
+
+function _bashify_path -d "Converts a fish path to something bash can recognize"
+    set fishy_path $argv
+    set bashy_path $fishy_path[1]
+    for path_part in $fishy_path[2..-1]
+        set bashy_path "$bashy_path:$path_part"
+    end
+    echo $bashy_path
+end
+
+function _fishify_path -d "Converts a bash path to something fish can recognize"
+    echo $argv | tr ':' '\n'
+end
+
+function deactivate -d 'Exit virtualenv mode and return to the normal environment.'
+    # reset old environment variables
+    if test -n "$_OLD_VIRTUAL_PATH"
+        # https://github.com/fish-shell/fish-shell/issues/436 altered PATH handling
+        if test (echo $FISH_VERSION | head -c 1) -lt 3
+            set -gx PATH (_fishify_path "$_OLD_VIRTUAL_PATH")
+        else
+            set -gx PATH $_OLD_VIRTUAL_PATH
+        end
+        set -e _OLD_VIRTUAL_PATH
+    end
+
+    if test -n "$_OLD_VIRTUAL_PYTHONHOME"
+        set -gx PYTHONHOME "$_OLD_VIRTUAL_PYTHONHOME"
+        set -e _OLD_VIRTUAL_PYTHONHOME
+    end
+
+    if test -n "$_OLD_FISH_PROMPT_OVERRIDE"
+       and functions -q _old_fish_prompt
+        # Set an empty local `$fish_function_path` to allow the removal of `fish_prompt` using `functions -e`.
+        set -l fish_function_path
+
+        # Erase virtualenv's `fish_prompt` and restore the original.
+        functions -e fish_prompt
+        functions -c _old_fish_prompt fish_prompt
+        functions -e _old_fish_prompt
+        set -e _OLD_FISH_PROMPT_OVERRIDE
+    end
+
+    set -e VIRTUAL_ENV
+    set -e VIRTUAL_ENV_PROMPT
+
+    if test "$argv[1]" != 'nondestructive'
+        # Self-destruct!
+        functions -e pydoc
+        functions -e deactivate
+        functions -e _bashify_path
+        functions -e _fishify_path
+    end
+end
+
+# Unset irrelevant variables.
+deactivate nondestructive
+
+set -gx VIRTUAL_ENV '{{ VIRTUAL_ENV_DIR }}'
+
+# https://github.com/fish-shell/fish-shell/issues/436 altered PATH handling
+if test (echo $FISH_VERSION | head -c 1) -lt 3
+   set -gx _OLD_VIRTUAL_PATH (_bashify_path $PATH)
+else
+    set -gx _OLD_VIRTUAL_PATH $PATH
+end
+set -gx PATH "$VIRTUAL_ENV"'/{{ BIN_NAME }}' $PATH
+
+# Prompt override provided?
+# If not, just use the environment name.
+if test -n '{{ VIRTUAL_PROMPT }}'
+    set -gx VIRTUAL_ENV_PROMPT '{{ VIRTUAL_PROMPT }}'
+else
+    set -gx VIRTUAL_ENV_PROMPT (basename "$VIRTUAL_ENV")
+end
+
+# Unset `$PYTHONHOME` if set.
+if set -q PYTHONHOME
+    set -gx _OLD_VIRTUAL_PYTHONHOME $PYTHONHOME
+    set -e PYTHONHOME
+end
+
+function pydoc
+    python -m pydoc $argv
+end
+
+if test -z "$VIRTUAL_ENV_DISABLE_PROMPT"
+    # Copy the current `fish_prompt` function as `_old_fish_prompt`.
+    functions -c fish_prompt _old_fish_prompt
+
+    function fish_prompt
+        # Run the user's prompt first; it might depend on (pipe)status.
+        set -l prompt (_old_fish_prompt)
+
+        printf '(%s) ' $VIRTUAL_ENV_PROMPT
+
+        string join -- \n $prompt # handle multi-line prompts
+    end
+
+    set -gx _OLD_FISH_PROMPT_OVERRIDE "$VIRTUAL_ENV"
+end

crates/uv-virtualenv/src/activator/activate.nu

@@ -0,0 +1,117 @@
+# Copyright (c) 2020-202x The virtualenv developers
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+# virtualenv activation module
+# Activate with `overlay use activate.nu`
+# Deactivate with `deactivate`, as usual
+#
+# To customize the overlay name, you can call `overlay use activate.nu as foo`,
+# but then simply `deactivate` won't work because it is just an alias to hide
+# the "activate" overlay. You'd need to call `overlay hide foo` manually.
+
+export-env {
+    def is-string [x] {
+        ($x | describe) == 'string'
+    }
+
+    def has-env [...names] {
+        $names | each {|n|
+            $n in $env
+        } | all {|i| $i == true}
+    }
+
+    # Emulates a `test -z`, but btter as it handles e.g 'false'
+    def is-env-true [name: string] {
+      if (has-env $name) {
+        # Try to parse 'true', '0', '1', and fail if not convertible
+        let parsed = (do -i { $env | get $name | into bool })
+        if ($parsed | describe) == 'bool' {
+          $parsed
+        } else {
+          not ($env | get -i $name | is-empty)
+        }
+      } else {
+        false
+      }
+    }
+
+    let virtual_env = '{{ VIRTUAL_ENV_DIR }}'
+    let bin = '{{ BIN_NAME }}'
+
+    let is_windows = ($nu.os-info.family) == 'windows'
+    let path_name = (if (has-env 'Path') {
+            'Path'
+        } else {
+            'PATH'
+        }
+    )
+
+    let venv_path = ([$virtual_env $bin] | path join)
+    let new_path = ($env | get $path_name | prepend $venv_path)
+
+    # If there is no default prompt, then use the env name instead
+    let virtual_env_prompt = (if ('{{ VIRTUAL_PROMPT }}' | is-empty) {
+        ($virtual_env | path basename)
+    } else {
+        '{{ VIRTUAL_PROMPT }}'
+    })
+
+    let new_env = {
+        $path_name         : $new_path
+        VIRTUAL_ENV        : $virtual_env
+        VIRTUAL_ENV_PROMPT : $virtual_env_prompt
+    }
+
+    let new_env = (if (is-env-true 'VIRTUAL_ENV_DISABLE_PROMPT') {
+      $new_env
+    } else {
+      # Creating the new prompt for the session
+      let virtual_prefix = $'(char lparen)($virtual_env_prompt)(char rparen) '
+
+      # Back up the old prompt builder
+      let old_prompt_command = (if (has-env 'PROMPT_COMMAND') {
+              $env.PROMPT_COMMAND
+          } else {
+              ''
+        })
+
+      let new_prompt = (if (has-env 'PROMPT_COMMAND') {
+          if 'closure' in ($old_prompt_command | describe) {
+              {|| $'($virtual_prefix)(do $old_prompt_command)' }
+          } else {
+              {|| $'($virtual_prefix)($old_prompt_command)' }
+          }
+      } else {
+          {|| $'($virtual_prefix)' }
+      })
+
+      $new_env | merge {
+        PROMPT_COMMAND      : $new_prompt
+        VIRTUAL_PREFIX      : $virtual_prefix
+      }
+    })
+
+    # Environment variables that will be loaded as the virtual env
+    load-env $new_env
+}
+
+export alias pydoc = python -m pydoc
+export alias deactivate = overlay hide activate

crates/uv-virtualenv/src/activator/activate.ps1

@@ -0,0 +1,82 @@
+# Copyright (c) 2020-202x The virtualenv developers
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+$script:THIS_PATH = $myinvocation.mycommand.path
+$script:BASE_DIR = Split-Path (Resolve-Path "$THIS_PATH/..") -Parent
+
+function global:deactivate([switch] $NonDestructive) {
+    if (Test-Path variable:_OLD_VIRTUAL_PATH) {
+        $env:PATH = $variable:_OLD_VIRTUAL_PATH
+        Remove-Variable "_OLD_VIRTUAL_PATH" -Scope global
+    }
+
+    if (Test-Path function:_old_virtual_prompt) {
+        $function:prompt = $function:_old_virtual_prompt
+        Remove-Item function:\_old_virtual_prompt
+    }
+
+    if ($env:VIRTUAL_ENV) {
+        Remove-Item env:VIRTUAL_ENV -ErrorAction SilentlyContinue
+    }
+
+    if ($env:VIRTUAL_ENV_PROMPT) {
+        Remove-Item env:VIRTUAL_ENV_PROMPT -ErrorAction SilentlyContinue
+    }
+
+    if (!$NonDestructive) {
+        # Self destruct!
+        Remove-Item function:deactivate
+        Remove-Item function:pydoc
+    }
+}
+
+function global:pydoc {
+    python -m pydoc $args
+}
+
+# unset irrelevant variables
+deactivate -nondestructive
+
+$VIRTUAL_ENV = $BASE_DIR
+$env:VIRTUAL_ENV = $VIRTUAL_ENV
+
+if ("{{ VIRTUAL_PROMPT }}" -ne "") {
+    $env:VIRTUAL_ENV_PROMPT = "{{ VIRTUAL_PROMPT }}"
+}
+else {
+    $env:VIRTUAL_ENV_PROMPT = $( Split-Path $env:VIRTUAL_ENV -Leaf )
+}
+
+New-Variable -Scope global -Name _OLD_VIRTUAL_PATH -Value $env:PATH
+
+$env:PATH = "$env:VIRTUAL_ENV/{{ BIN_NAME }};" + $env:PATH
+if (!$env:VIRTUAL_ENV_DISABLE_PROMPT) {
+    function global:_old_virtual_prompt {
+        ""
+    }
+    $function:_old_virtual_prompt = $function:prompt
+
+    function global:prompt {
+        # Add the custom prefix to the existing prompt
+        $previous_prompt_value = & $function:_old_virtual_prompt
+        ("(" + $env:VIRTUAL_ENV_PROMPT + ") " + $previous_prompt_value)
+    }
+}

crates/uv-virtualenv/src/activator/activate_this.py

@@ -0,0 +1,57 @@
+# Copyright (c) 2020-202x The virtualenv developers
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+"""
+Activate virtualenv for current interpreter:
+
+Use exec(open(this_file).read(), {'__file__': this_file}).
+
+This can be used when you must use an existing Python interpreter, not the virtualenv bin/python.
+"""  # noqa: D415
+from __future__ import annotations
+
+import os
+import site
+import sys
+
+try:
+    abs_file = os.path.abspath(__file__)
+except NameError as exc:
+    msg = "You must use exec(open(this_file).read(), {'__file__': this_file}))"
+    raise AssertionError(msg) from exc
+
+bin_dir = os.path.dirname(abs_file)
+base = bin_dir[: -len("{{ BIN_NAME }}") - 1]  # strip away the bin part from the __file__, plus the path separator
+
+# prepend bin to PATH (this file is inside the bin directory)
+os.environ["PATH"] = os.pathsep.join([bin_dir, *os.environ.get("PATH", "").split(os.pathsep)])
+os.environ["VIRTUAL_ENV"] = base  # virtual env is right above bin directory
+os.environ["VIRTUAL_ENV_PROMPT"] = "" or os.path.basename(base)  # noqa: SIM222
+
+# add the virtual environments libraries to the host python import mechanism
+prev_length = len(sys.path)
+for lib in "{{ RELATIVE_SITE_PACKAGES }}".split(os.pathsep):
+    path = os.path.realpath(os.path.join(bin_dir, lib))
+    site.addsitedir(path.decode("utf-8") if "" else path)
+sys.path[:] = sys.path[prev_length:] + sys.path[0:prev_length]
+
+sys.real_prefix = sys.prefix
+sys.prefix = base

crates/uv-virtualenv/src/activator/deactivate.bat

@@ -0,0 +1,39 @@
+@REM Copyright (c) 2020-202x The virtualenv developers
+@REM
+@REM Permission is hereby granted, free of charge, to any person obtaining
+@REM a copy of this software and associated documentation files (the
+@REM "Software"), to deal in the Software without restriction, including
+@REM without limitation the rights to use, copy, modify, merge, publish,
+@REM distribute, sublicense, and/or sell copies of the Software, and to
+@REM permit persons to whom the Software is furnished to do so, subject to
+@REM the following conditions:
+@REM
+@REM The above copyright notice and this permission notice shall be
+@REM included in all copies or substantial portions of the Software.
+@REM
+@REM THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+@REM EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+@REM MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+@REM NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+@REM LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+@REM OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+@REM WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+@set VIRTUAL_ENV=
+@set VIRTUAL_ENV_PROMPT=
+
+@REM Don't use () to avoid problems with them in %PATH%
+@if not defined _OLD_VIRTUAL_PROMPT @goto ENDIFVPROMPT
+    @set "PROMPT=%_OLD_VIRTUAL_PROMPT%"
+    @set _OLD_VIRTUAL_PROMPT=
+:ENDIFVPROMPT
+
+@if not defined _OLD_VIRTUAL_PYTHONHOME @goto ENDIFVHOME
+    @set "PYTHONHOME=%_OLD_VIRTUAL_PYTHONHOME%"
+    @set _OLD_VIRTUAL_PYTHONHOME=
+:ENDIFVHOME
+
+@if not defined _OLD_VIRTUAL_PATH @goto ENDIFVPATH
+    @set "PATH=%_OLD_VIRTUAL_PATH%"
+    @set _OLD_VIRTUAL_PATH=
+:ENDIFVPATH

crates/uv-virtualenv/src/activator/pydoc.bat

@@ -0,0 +1,22 @@
+@REM Copyright (c) 2020-202x The virtualenv developers
+@REM
+@REM Permission is hereby granted, free of charge, to any person obtaining
+@REM a copy of this software and associated documentation files (the
+@REM "Software"), to deal in the Software without restriction, including
+@REM without limitation the rights to use, copy, modify, merge, publish,
+@REM distribute, sublicense, and/or sell copies of the Software, and to
+@REM permit persons to whom the Software is furnished to do so, subject to
+@REM the following conditions:
+@REM
+@REM The above copyright notice and this permission notice shall be
+@REM included in all copies or substantial portions of the Software.
+@REM
+@REM THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+@REM EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+@REM MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+@REM NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+@REM LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+@REM OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+@REM WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+python.exe -m pydoc %*

crates/uv-virtualenv/src/bare.rs

@@ -0,0 +1,323 @@
+//! Create a bare virtualenv without any packages install
+
+use std::env;
+use std::env::consts::EXE_SUFFIX;
+use std::io;
+use std::io::{BufWriter, Write};
+
+use camino::{FromPathBufError, Utf8Path, Utf8PathBuf};
+use fs_err as fs;
+use fs_err::File;
+use tracing::info;
+use uv_fs::Simplified;
+
+use uv_interpreter::{Interpreter, SysconfigPaths, Virtualenv};
+
+use crate::{Error, Prompt};
+
+/// The bash activate scripts with the venv dependent paths patches out
+const ACTIVATE_TEMPLATES: &[(&str, &str)] = &[
+    ("activate", include_str!("activator/activate")),
+    ("activate.csh", include_str!("activator/activate.csh")),
+    ("activate.fish", include_str!("activator/activate.fish")),
+    ("activate.nu", include_str!("activator/activate.nu")),
+    ("activate.ps1", include_str!("activator/activate.ps1")),
+    ("activate.bat", include_str!("activator/activate.bat")),
+    ("deactivate.bat", include_str!("activator/deactivate.bat")),
+    ("pydoc.bat", include_str!("activator/pydoc.bat")),
+    (
+        "activate_this.py",
+        include_str!("activator/activate_this.py"),
+    ),
+];
+const VIRTUALENV_PATCH: &str = include_str!("_virtualenv.py");
+
+/// Very basic `.cfg` file format writer.
+fn write_cfg(f: &mut impl Write, data: &[(String, String)]) -> io::Result<()> {
+    for (key, value) in data {
+        writeln!(f, "{key} = {value}")?;
+    }
+    Ok(())
+}
+
+/// Write all the files that belong to a venv without any packages installed.
+pub fn create_bare_venv(
+    location: &Utf8Path,
+    interpreter: &Interpreter,
+    prompt: Prompt,
+    system_site_packages: bool,
+    extra_cfg: Vec<(String, String)>,
+) -> Result<Virtualenv, Error> {
+    // We have to canonicalize the interpreter path, otherwise the home is set to the venv dir instead of the real root.
+    // This would make python-build-standalone fail with the encodings module not being found because its home is wrong.
+    let base_python: Utf8PathBuf = fs_err::canonicalize(interpreter.sys_executable())?
+        .try_into()
+        .map_err(|err: FromPathBufError| err.into_io_error())?;
+
+    // Validate the existing location.
+    match location.metadata() {
+        Ok(metadata) => {
+            if metadata.is_file() {
+                return Err(Error::IO(io::Error::new(
+                    io::ErrorKind::AlreadyExists,
+                    format!("File exists at `{location}`"),
+                )));
+            } else if metadata.is_dir() {
+                if location.join("pyvenv.cfg").is_file() {
+                    info!("Removing existing directory");
+                    fs::remove_dir_all(location)?;
+                    fs::create_dir_all(location)?;
+                } else if location
+                    .read_dir()
+                    .is_ok_and(|mut dir| dir.next().is_none())
+                {
+                    info!("Ignoring empty directory");
+                } else {
+                    return Err(Error::IO(io::Error::new(
+                        io::ErrorKind::AlreadyExists,
+                        format!("The directory `{location}` exists, but it's not a virtualenv"),
+                    )));
+                }
+            }
+        }
+        Err(err) if err.kind() == io::ErrorKind::NotFound => {
+            fs::create_dir_all(location)?;
+        }
+        Err(err) => return Err(Error::IO(err)),
+    }
+
+    let location = location.canonicalize_utf8()?;
+
+    let bin_name = if cfg!(unix) {
+        "bin"
+    } else if cfg!(windows) {
+        "Scripts"
+    } else {
+        unimplemented!("Only Windows and Unix are supported")
+    };
+    let scripts = location.join(bin_name);
+    let prompt = match prompt {
+        Prompt::CurrentDirectoryName => env::current_dir()?
+            .file_name()
+            .map(|name| name.to_string_lossy().to_string()),
+        Prompt::Static(value) => Some(value),
+        Prompt::None => None,
+    };
+
+    // Add the CACHEDIR.TAG.
+    cachedir::ensure_tag(&location)?;
+
+    // Create a `.gitignore` file to ignore all files in the venv.
+    fs::write(location.join(".gitignore"), "*")?;
+
+    // Different names for the python interpreter
+    fs::create_dir(&scripts)?;
+    let executable = scripts.join(format!("python{EXE_SUFFIX}"));
+
+    // No symlinking on Windows, at least not on a regular non-dev non-admin Windows install.
+    #[cfg(unix)]
+    {
+        use fs_err::os::unix::fs::symlink;
+
+        symlink(&base_python, &executable)?;
+        symlink(
+            "python",
+            scripts.join(format!("python{}", interpreter.python_major())),
+        )?;
+        symlink(
+            "python",
+            scripts.join(format!(
+                "python{}.{}",
+                interpreter.python_major(),
+                interpreter.python_minor(),
+            )),
+        )?;
+    }
+
+    #[cfg(windows)]
+    {
+        // https://github.com/python/cpython/blob/d457345bbc6414db0443819290b04a9a4333313d/Lib/venv/__init__.py#L261-L267
+        // https://github.com/pypa/virtualenv/blob/d9fdf48d69f0d0ca56140cf0381edbb5d6fe09f5/src/virtualenv/create/via_global_ref/builtin/cpython/cpython3.py#L78-L83
+        // There's two kinds of applications on windows: Those that allocate a console (python.exe) and those that
+        // don't because they use window(s) (pythonw.exe).
+        for python_exe in ["python.exe", "pythonw.exe"] {
+            let shim = interpreter
+                .stdlib()
+                .join("venv")
+                .join("scripts")
+                .join("nt")
+                .join(python_exe);
+            fs_err::copy(shim, scripts.join(python_exe))?;
+        }
+    }
+    #[cfg(not(any(unix, windows)))]
+    {
+        compile_error!("Only Windows and Unix are supported")
+    }
+
+    // Add all the activate scripts for different shells
+    for (name, template) in ACTIVATE_TEMPLATES {
+        let relative_site_packages = if cfg!(unix) {
+            format!(
+                "../lib/{}{}.{}/site-packages",
+                interpreter.site_packages_python(),
+                interpreter.python_major(),
+                interpreter.python_minor(),
+            )
+        } else if cfg!(windows) {
+            "../Lib/site-packages".to_string()
+        } else {
+            unimplemented!("Only Windows and Unix are supported")
+        };
+        let activator = template
+            .replace(
+                "{{ VIRTUAL_ENV_DIR }}",
+                // SAFETY: `unwrap` is guaranteed to succeed because `location` is an `Utf8PathBuf`.
+                location.simplified().to_str().unwrap(),
+            )
+            .replace("{{ BIN_NAME }}", bin_name)
+            .replace(
+                "{{ VIRTUAL_PROMPT }}",
+                prompt.as_deref().unwrap_or_default(),
+            )
+            .replace(
+                "{{ RELATIVE_SITE_PACKAGES }}",
+                relative_site_packages.as_str(),
+            );
+        fs::write(scripts.join(name), activator)?;
+    }
+
+    // pyvenv.cfg
+    let python_home = if cfg!(unix) {
+        // On Linux and Mac, Python is symlinked so the base home is the parent of the resolved-by-canonicalize path.
+        base_python
+            .parent()
+            .ok_or_else(|| {
+                io::Error::new(
+                    io::ErrorKind::NotFound,
+                    "The python interpreter needs to have a parent directory",
+                )
+            })?
+            .to_string()
+    } else if cfg!(windows) {
+        // `virtualenv` seems to rely on the undocumented, private `sys._base_executable`. When I tried,
+        // `sys.base_prefix` was the same as the parent of `sys._base_executable`, but a much simpler logic and
+        // documented.
+        // https://github.com/pypa/virtualenv/blob/d9fdf48d69f0d0ca56140cf0381edbb5d6fe09f5/src/virtualenv/discovery/py_info.py#L136-L156
+        interpreter.base_prefix().display().to_string()
+    } else {
+        unimplemented!("Only Windows and Unix are supported")
+    };
+
+    // Validate extra_cfg
+    let reserved_keys = [
+        "home",
+        "implementation",
+        "version_info",
+        "include-system-site-packages",
+        "base-prefix",
+        "base-exec-prefix",
+        "base-executable",
+        "prompt",
+    ];
+    for (key, _) in &extra_cfg {
+        if reserved_keys.contains(&key.as_str()) {
+            return Err(Error::ReservedConfigKey(key.to_string()));
+        }
+    }
+
+    let mut pyvenv_cfg_data: Vec<(String, String)> = vec![
+        ("home".to_string(), python_home),
+        (
+            "implementation".to_string(),
+            interpreter.markers().platform_python_implementation.clone(),
+        ),
+        (
+            "version_info".to_string(),
+            interpreter.markers().python_full_version.string.clone(),
+        ),
+        (
+            "include-system-site-packages".to_string(),
+            if system_site_packages {
+                "true".to_string()
+            } else {
+                "false".to_string()
+            },
+        ),
+        (
+            "base-prefix".to_string(),
+            interpreter.base_prefix().to_string_lossy().to_string(),
+        ),
+        (
+            "base-exec-prefix".to_string(),
+            interpreter.base_exec_prefix().to_string_lossy().to_string(),
+        ),
+        ("base-executable".to_string(), base_python.to_string()),
+    ]
+    .into_iter()
+    .chain(extra_cfg)
+    .collect();
+
+    if let Some(prompt) = prompt {
+        pyvenv_cfg_data.push(("prompt".to_string(), prompt));
+    }
+
+    let mut pyvenv_cfg = BufWriter::new(File::create(location.join("pyvenv.cfg"))?);
+    write_cfg(&mut pyvenv_cfg, &pyvenv_cfg_data)?;
+    drop(pyvenv_cfg);
+
+    // Construct the path to the `site-packages` directory.
+    let site_packages = if cfg!(unix) {
+        location
+            .join("lib")
+            .join(format!(
+                "{}{}.{}",
+                interpreter.site_packages_python(),
+                interpreter.python_major(),
+                interpreter.python_minor(),
+            ))
+            .join("site-packages")
+    } else if cfg!(windows) {
+        location.join("Lib").join("site-packages")
+    } else {
+        unimplemented!("Only Windows and Unix are supported")
+    };
+
+    // Construct the path to the `platstdlib` directory.
+    let platstdlib = if cfg!(windows) {
+        location.join("Lib")
+    } else {
+        location
+            .join("lib")
+            .join(format!(
+                "{}{}.{}",
+                interpreter.site_packages_python(),
+                interpreter.python_major(),
+                interpreter.python_minor()
+            ))
+            .join("site-packages")
+    };
+
+    // Populate `site-packages` with a `_virtualenv.py` file.
+    fs::create_dir_all(&site_packages)?;
+    fs::write(site_packages.join("_virtualenv.py"), VIRTUALENV_PATCH)?;
+    fs::write(site_packages.join("_virtualenv.pth"), "import _virtualenv")?;
+
+    Ok(Virtualenv {
+        root: location.clone().into_std_path_buf(),
+        executable: executable.into_std_path_buf(),
+        sysconfig_paths: SysconfigPaths {
+            // Paths that were already constructed above.
+            scripts: scripts.into_std_path_buf(),
+            platstdlib: platstdlib.into_std_path_buf(),
+            // Set `purelib` and `platlib` to the same value.
+            purelib: site_packages.clone().into_std_path_buf(),
+            platlib: site_packages.into_std_path_buf(),
+            // Inherited from the interpreter.
+            stdlib: interpreter.stdlib().to_path_buf(),
+            include: interpreter.include().to_path_buf(),
+            platinclude: interpreter.platinclude().to_path_buf(),
+            data: location.into_std_path_buf(),
+        },
+    })
+}

crates/uv-virtualenv/src/lib.rs

@@ -0,0 +1,73 @@
+use std::io;
+use std::path::Path;
+
+use camino::{FromPathError, Utf8Path};
+use thiserror::Error;
+
+use platform_host::PlatformError;
+use uv_interpreter::{Interpreter, PythonEnvironment};
+
+pub use crate::bare::create_bare_venv;
+
+mod bare;
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error(transparent)]
+    IO(#[from] io::Error),
+    #[error("Failed to determine python interpreter to use")]
+    InterpreterError(#[from] uv_interpreter::Error),
+    #[error(transparent)]
+    Platform(#[from] PlatformError),
+    #[error("Reserved key used for pyvenv.cfg: {0}")]
+    ReservedConfigKey(String),
+}
+
+/// The value to use for the shell prompt when inside a virtual environment.
+#[derive(Debug)]
+pub enum Prompt {
+    /// Use the current directory name as the prompt.
+    CurrentDirectoryName,
+    /// Use the fixed string as the prompt.
+    Static(String),
+    /// Default to no prompt. The prompt is then set by the activator script
+    /// to the virtual environment's directory name.
+    None,
+}
+
+impl Prompt {
+    /// Determine the prompt value to be used from the command line arguments.
+    pub fn from_args(prompt: Option<String>) -> Self {
+        match prompt {
+            Some(prompt) if prompt == "." => Self::CurrentDirectoryName,
+            Some(prompt) => Self::Static(prompt),
+            None => Self::None,
+        }
+    }
+}
+
+/// Create a virtualenv.
+pub fn create_venv(
+    location: &Path,
+    interpreter: Interpreter,
+    prompt: Prompt,
+    system_site_packages: bool,
+    extra_cfg: Vec<(String, String)>,
+) -> Result<PythonEnvironment, Error> {
+    // Create the virtualenv at the given location.
+    let location: &Utf8Path = location
+        .try_into()
+        .map_err(|err: FromPathError| err.into_io_error())?;
+    let virtualenv = create_bare_venv(
+        location,
+        &interpreter,
+        prompt,
+        system_site_packages,
+        extra_cfg,
+    )?;
+
+    // Create the corresponding `PythonEnvironment`.
+    let interpreter = interpreter.with_virtualenv(virtualenv);
+    let root = interpreter.prefix().to_path_buf();
+    Ok(PythonEnvironment::from_interpreter(interpreter, root))
+}

crates/uv-virtualenv/src/main.rs

@@ -0,0 +1,77 @@
+use std::error::Error;
+use std::process::ExitCode;
+use std::time::Instant;
+
+use anstream::eprintln;
+use camino::Utf8PathBuf;
+use clap::Parser;
+use directories::ProjectDirs;
+use tracing::info;
+use tracing_subscriber::layer::SubscriberExt;
+use tracing_subscriber::util::SubscriberInitExt;
+use tracing_subscriber::{fmt, EnvFilter};
+
+use platform_host::Platform;
+use uv_cache::Cache;
+use uv_interpreter::{find_default_python, find_requested_python};
+use uv_virtualenv::{create_bare_venv, Prompt};
+
+#[derive(Parser, Debug)]
+struct Cli {
+    path: Option<Utf8PathBuf>,
+    #[clap(short, long)]
+    python: Option<String>,
+    #[clap(long)]
+    prompt: Option<String>,
+    #[clap(long)]
+    system_site_packages: bool,
+}
+
+fn run() -> Result<(), uv_virtualenv::Error> {
+    let cli = Cli::parse();
+    let location = cli.path.unwrap_or(Utf8PathBuf::from(".venv"));
+    let platform = Platform::current()?;
+    let cache = if let Some(project_dirs) = ProjectDirs::from("", "", "uv-virtualenv") {
+        Cache::from_path(project_dirs.cache_dir())?
+    } else {
+        Cache::from_path(".cache")?
+    };
+    let interpreter = if let Some(python_request) = &cli.python {
+        find_requested_python(python_request, &platform, &cache)?.ok_or(
+            uv_interpreter::Error::NoSuchPython(python_request.to_string()),
+        )?
+    } else {
+        find_default_python(&platform, &cache)?
+    };
+    create_bare_venv(
+        &location,
+        &interpreter,
+        Prompt::from_args(cli.prompt),
+        cli.system_site_packages,
+        Vec::new(),
+    )?;
+    Ok(())
+}
+
+fn main() -> ExitCode {
+    tracing_subscriber::registry()
+        .with(fmt::layer())
+        .with(EnvFilter::from_default_env())
+        .init();
+
+    let start = Instant::now();
+    let result = run();
+    info!("Took {}ms", start.elapsed().as_millis());
+    if let Err(err) = result {
+        eprintln!("💥 virtualenv creator failed");
+
+        let mut last_error: Option<&(dyn Error + 'static)> = Some(&err);
+        while let Some(err) = last_error {
+            eprintln!("  Caused by: {err}");
+            last_error = err.source();
+        }
+        ExitCode::FAILURE
+    } else {
+        ExitCode::SUCCESS
+    }
+}