Add support for using Python 3.6 interpreters

.github/workflows/test-system.yml

@@ -95,6 +95,54 @@ jobs:
       - name: "Validate global Python install"
         run: python scripts/check_system_python.py --uv ./uv
 
+  system-test-python-36:
+    timeout-minutes: 10
+    name: "python3.6 on debian buster"
+    runs-on: ubuntu-latest
+    container: python:3.6-buster
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: "Download binary"
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
+        with:
+          name: uv-linux-musl-${{ inputs.sha }}
+
+      - name: "Prepare binary"
+        run: chmod +x ./uv
+
+      - name: "Print Python path"
+        run: echo $(which python3)
+
+      - name: "Validate global Python install"
+        run: python3 scripts/check_system_python.py --uv ./uv
+
+  system-test-python-37:
+    timeout-minutes: 10
+    name: "python3.7 on debian buster"
+    runs-on: ubuntu-latest
+    container: python:3.7-buster
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: "Download binary"
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
+        with:
+          name: uv-linux-musl-${{ inputs.sha }}
+
+      - name: "Prepare binary"
+        run: chmod +x ./uv
+
+      - name: "Print Python path"
+        run: echo $(which python3)
+
+      - name: "Validate global Python install"
+        run: python3 scripts/check_system_python.py --uv ./uv
+
   # Currently failing, see https://github.com/astral-sh/uv/issues/13811
   # system-test-opensuse:
   #   timeout-minutes: 5

crates/uv-python/python/get_interpreter_info.py

@@ -444,7 +444,7 @@ def get_operating_system_and_architecture():
         version = None
         architecture = version_arch
 
-    if sys.version_info < (3, 7):
+    if sys.version_info < (3, 6):
         print(
             json.dumps(
                 {

crates/uv-python/python/packaging/README.md

@@ -4,3 +4,9 @@ This directory contains vendored [pypa/packaging](https://github.com/pypa/packag
 [cc938f984bbbe43c5734b9656c9837ab3a28191f](https://github.com/pypa/packaging/tree/cc938f984bbbe43c5734b9656c9837ab3a28191f/src/packaging).
 
 The files are licensed under BSD-2-Clause OR Apache-2.0.
+
+## Patches
+
+The following patches have been applied:
+
+- [python36-support.patch](./python36-support.patch)

crates/uv-python/python/packaging/_elffile.py

@@ -8,8 +8,6 @@
 ELF header: https://refspecs.linuxfoundation.org/elf/gabi4+/ch4.eheader.html
 """
 
-from __future__ import annotations
-
 import enum
 import os
 import struct
@@ -88,11 +86,11 @@ def __init__(self, f: IO[bytes]) -> None:
         except struct.error as e:
             raise ELFInvalid("unable to parse machine and section information") from e
 
-    def _read(self, fmt: str) -> tuple[int, ...]:
+    def _read(self, fmt: str) -> "tuple[int, ...]":
         return struct.unpack(fmt, self._f.read(struct.calcsize(fmt)))
 
     @property
-    def interpreter(self) -> str | None:
+    def interpreter(self) -> "str | None":
         """
         The path recorded in the ``PT_INTERP`` section header.
         """

crates/uv-python/python/packaging/_manylinux.py

@@ -1,5 +1,3 @@
-from __future__ import annotations
-
 import collections
 import contextlib
 import functools
@@ -19,7 +17,7 @@
 # `os.PathLike` not a generic type until Python 3.9, so sticking with `str`
 # as the type for `path` until then.
 @contextlib.contextmanager
-def _parse_elf(path: str) -> Generator[ELFFile | None, None, None]:
+def _parse_elf(path: str) -> "Generator[ELFFile | None, None, None]":
     try:
         with open(path, "rb") as f:
             yield ELFFile(f)
@@ -74,15 +72,15 @@ def _have_compatible_abi(executable: str, archs: Sequence[str]) -> bool:
 # For now, guess what the highest minor version might be, assume it will
 # be 50 for testing. Once this actually happens, update the dictionary
 # with the actual value.
-_LAST_GLIBC_MINOR: dict[int, int] = collections.defaultdict(lambda: 50)
+_LAST_GLIBC_MINOR: "dict[int, int]" = collections.defaultdict(lambda: 50)
 
 
 class _GLibCVersion(NamedTuple):
     major: int
     minor: int
 
 
-def _glibc_version_string_confstr() -> str | None:
+def _glibc_version_string_confstr() -> "str | None":
     """
     Primary implementation of glibc_version_string using os.confstr.
     """
@@ -92,7 +90,7 @@ def _glibc_version_string_confstr() -> str | None:
     # https://github.com/python/cpython/blob/fcf1d003bf4f0100c/Lib/platform.py#L175-L183
     try:
         # Should be a string like "glibc 2.17".
-        version_string: str | None = os.confstr("CS_GNU_LIBC_VERSION")
+        version_string: "str | None" = os.confstr("CS_GNU_LIBC_VERSION")
         assert version_string is not None
         _, version = version_string.rsplit()
     except (AssertionError, AttributeError, OSError, ValueError):
@@ -101,7 +99,7 @@ def _glibc_version_string_confstr() -> str | None:
     return version
 
 
-def _glibc_version_string_ctypes() -> str | None:
+def _glibc_version_string_ctypes() -> "str | None":
     """
     Fallback implementation of glibc_version_string using ctypes.
     """
@@ -145,7 +143,7 @@ def _glibc_version_string_ctypes() -> str | None:
     return version_str
 
 
-def _glibc_version_string() -> str | None:
+def _glibc_version_string() -> "str | None":
     """Returns glibc version string, or None if not using glibc."""
     return _glibc_version_string_confstr() or _glibc_version_string_ctypes()
 
@@ -203,7 +201,7 @@ def _is_compatible(arch: str, version: _GLibCVersion) -> bool:
     return True
 
 
-_LEGACY_MANYLINUX_MAP: dict[_GLibCVersion, str] = {
+_LEGACY_MANYLINUX_MAP: "dict[_GLibCVersion, str]" = {
     # CentOS 7 w/ glibc 2.17 (PEP 599)
     _GLibCVersion(2, 17): "manylinux2014",
     # CentOS 6 w/ glibc 2.12 (PEP 571)

crates/uv-python/python/packaging/_musllinux.py

@@ -4,8 +4,6 @@
 linked against musl, and what musl version is used.
 """
 
-from __future__ import annotations
-
 import functools
 import re
 import subprocess
@@ -20,7 +18,7 @@ class _MuslVersion(NamedTuple):
     minor: int
 
 
-def _parse_musl_version(output: str) -> _MuslVersion | None:
+def _parse_musl_version(output: str) -> "_MuslVersion | None":
     lines = [n for n in (n.strip() for n in output.splitlines()) if n]
     if len(lines) < 2 or lines[0][:4] != "musl":
         return None
@@ -31,7 +29,7 @@ def _parse_musl_version(output: str) -> _MuslVersion | None:
 
 
 @functools.lru_cache()
-def _get_musl_version(executable: str) -> _MuslVersion | None:
+def _get_musl_version(executable: str) -> "_MuslVersion | None":
     """Detect currently-running musl runtime version.
 
     This is done by checking the specified executable's dynamic linking

crates/uv-python/python/packaging/python36-support.patch

@@ -0,0 +1,139 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+Subject: [PATCH] python36-support
+
+Remove `from __future__ import annotations` and quote PEP 604 (`X | Y`) union
+annotations and PEP 585 (`dict[K, V]`) lowercase generics so these vendored
+modules remain compatible with Python 3.6.
+
+---
+diff --git a/crates/uv-python/python/packaging/_elffile.py b/crates/uv-python/python/packaging/_elffile.py
+index 8dc7fb32a..f1907a595 100644
+--- a/crates/uv-python/python/packaging/_elffile.py
++++ b/crates/uv-python/python/packaging/_elffile.py
+@@ -8,8 +8,6 @@ Based on: https://gist.github.com/lyssdod/f51579ae8d93c8657a5564aefc2ffbca
+ ELF header: https://refspecs.linuxfoundation.org/elf/gabi4+/ch4.eheader.html
+ """
+
+-from __future__ import annotations
+-
+ import enum
+ import os
+ import struct
+@@ -88,11 +86,11 @@ class ELFFile:
+         except struct.error as e:
+             raise ELFInvalid("unable to parse machine and section information") from e
+
+-    def _read(self, fmt: str) -> tuple[int, ...]:
++    def _read(self, fmt: str) -> "tuple[int, ...]":
+         return struct.unpack(fmt, self._f.read(struct.calcsize(fmt)))
+
+     @property
+-    def interpreter(self) -> str | None:
++    def interpreter(self) -> "str | None":
+         """
+         The path recorded in the ``PT_INTERP`` section header.
+         """
+diff --git a/crates/uv-python/python/packaging/_manylinux.py b/crates/uv-python/python/packaging/_manylinux.py
+index 7b52a5581..d3c871aab 100644
+--- a/crates/uv-python/python/packaging/_manylinux.py
++++ b/crates/uv-python/python/packaging/_manylinux.py
+@@ -1,5 +1,3 @@
+-from __future__ import annotations
+-
+ import collections
+ import contextlib
+ import functools
+@@ -19,7 +17,7 @@ EF_ARM_ABI_FLOAT_HARD = 0x00000400
+ # `os.PathLike` not a generic type until Python 3.9, so sticking with `str`
+ # as the type for `path` until then.
+ @contextlib.contextmanager
+-def _parse_elf(path: str) -> Generator[ELFFile | None, None, None]:
++def _parse_elf(path: str) -> "Generator[ELFFile | None, None, None]":
+     try:
+         with open(path, "rb") as f:
+             yield ELFFile(f)
+@@ -74,7 +72,7 @@ def _have_compatible_abi(executable: str, archs: Sequence[str]) -> bool:
+ # For now, guess what the highest minor version might be, assume it will
+ # be 50 for testing. Once this actually happens, update the dictionary
+ # with the actual value.
+-_LAST_GLIBC_MINOR: dict[int, int] = collections.defaultdict(lambda: 50)
++_LAST_GLIBC_MINOR: "dict[int, int]" = collections.defaultdict(lambda: 50)
+
+
+ class _GLibCVersion(NamedTuple):
+@@ -82,7 +80,7 @@ class _GLibCVersion(NamedTuple):
+     minor: int
+
+
+-def _glibc_version_string_confstr() -> str | None:
++def _glibc_version_string_confstr() -> "str | None":
+     """
+     Primary implementation of glibc_version_string using os.confstr.
+     """
+@@ -92,7 +90,7 @@ def _glibc_version_string_confstr() -> str | None:
+     # https://github.com/python/cpython/blob/fcf1d003bf4f0100c/Lib/platform.py#L175-L183
+     try:
+         # Should be a string like "glibc 2.17".
+-        version_string: str | None = os.confstr("CS_GNU_LIBC_VERSION")
++        version_string: "str | None" = os.confstr("CS_GNU_LIBC_VERSION")
+         assert version_string is not None
+         _, version = version_string.rsplit()
+     except (AssertionError, AttributeError, OSError, ValueError):
+@@ -101,7 +99,7 @@ def _glibc_version_string_confstr() -> str | None:
+     return version
+
+
+-def _glibc_version_string_ctypes() -> str | None:
++def _glibc_version_string_ctypes() -> "str | None":
+     """
+     Fallback implementation of glibc_version_string using ctypes.
+     """
+@@ -145,7 +143,7 @@ def _glibc_version_string_ctypes() -> str | None:
+     return version_str
+
+
+-def _glibc_version_string() -> str | None:
++def _glibc_version_string() -> "str | None":
+     """Returns glibc version string, or None if not using glibc."""
+     return _glibc_version_string_confstr() or _glibc_version_string_ctypes()
+
+@@ -203,7 +201,7 @@ def _is_compatible(arch: str, version: _GLibCVersion) -> bool:
+     return True
+
+
+-_LEGACY_MANYLINUX_MAP: dict[_GLibCVersion, str] = {
++_LEGACY_MANYLINUX_MAP: "dict[_GLibCVersion, str]" = {
+     # CentOS 7 w/ glibc 2.17 (PEP 599)
+     _GLibCVersion(2, 17): "manylinux2014",
+     # CentOS 6 w/ glibc 2.12 (PEP 571)
+diff --git a/crates/uv-python/python/packaging/_musllinux.py b/crates/uv-python/python/packaging/_musllinux.py
+index b4ca23804..40a72f05b 100644
+--- a/crates/uv-python/python/packaging/_musllinux.py
++++ b/crates/uv-python/python/packaging/_musllinux.py
+@@ -4,8 +4,6 @@ This module implements logic to detect if the currently running Python is
+ linked against musl, and what musl version is used.
+ """
+
+-from __future__ import annotations
+-
+ import functools
+ import re
+ import subprocess
+@@ -20,7 +18,7 @@ class _MuslVersion(NamedTuple):
+     minor: int
+
+
+-def _parse_musl_version(output: str) -> _MuslVersion | None:
++def _parse_musl_version(output: str) -> "_MuslVersion | None":
+     lines = [n for n in (n.strip() for n in output.splitlines()) if n]
+     if len(lines) < 2 or lines[0][:4] != "musl":
+         return None
+@@ -31,7 +29,7 @@ def _parse_musl_version(output: str) -> _MuslVersion | None:
+
+
+ @functools.lru_cache()
+-def _get_musl_version(executable: str) -> _MuslVersion | None:
++def _get_musl_version(executable: str) -> "_MuslVersion | None":
+     """Detect currently-running musl runtime version.
+
+     This is done by checking the specified executable's dynamic linking

crates/uv-python/src/discovery.rs

@@ -708,7 +708,7 @@ fn find_all_minor(
                     let minor = captures["minor"].parse().ok();
                     if let Some(minor) = minor {
                         // Optimization: Skip generally unsupported Python versions without querying.
-                        if minor < 7 {
+                        if minor < 6 {
                             return false;
                         }
                         // Optimization 2: Skip excluded Python (minor) versions without querying.
@@ -2751,23 +2751,23 @@ impl VersionRequest {
                 }
             }
             Self::MajorMinor(major, minor, _) => {
-                if (*major, *minor) < (3, 7) {
+                if (*major, *minor) < (3, 6) {
                     return Err(format!(
-                        "Python <3.7 is not supported but {major}.{minor} was requested."
+                        "Python <3.6 is not supported but {major}.{minor} was requested."
                     ));
                 }
             }
             Self::MajorMinorPatch(major, minor, patch, _) => {
-                if (*major, *minor) < (3, 7) {
+                if (*major, *minor) < (3, 6) {
                     return Err(format!(
-                        "Python <3.7 is not supported but {major}.{minor}.{patch} was requested."
+                        "Python <3.6 is not supported but {major}.{minor}.{patch} was requested."
                     ));
                 }
             }
             Self::MajorMinorPrerelease(major, minor, prerelease, _) => {
-                if (*major, *minor) < (3, 7) {
+                if (*major, *minor) < (3, 6) {
                     return Err(format!(
-                        "Python <3.7 is not supported but {major}.{minor}{prerelease} was requested."
+                        "Python <3.6 is not supported but {major}.{minor}{prerelease} was requested."
                     ));
                 }
             }

crates/uv-python/src/interpreter.rs

@@ -905,9 +905,9 @@ pub enum InterpreterInfoError {
     BrokenMacVer,
     #[error("Unknown operating system: `{operating_system}`")]
     UnknownOperatingSystem { operating_system: String },
-    #[error("Python {python_version} is not supported. Please use Python 3.8 or newer.")]
+    #[error("Python {python_version} is not supported. Please use Python 3.6 or newer.")]
     UnsupportedPythonVersion { python_version: String },
-    #[error("Python executable does not support `-I` flag. Please use Python 3.8 or newer.")]
+    #[error("Python executable does not support `-I` flag. Please use Python 3.6 or newer.")]
     UnsupportedPython,
     #[error(
         "Python installation is missing `distutils`, which is required for packaging on older Python versions. Your system may package it separately, e.g., as `python{python_major}-distutils` or `python{python_major}.{python_minor}-distutils`."