Prefer preferences with greater package versions (#10963)

## Summary

Closes https://github.com/astral-sh/uv/issues/10957.

crates/uv-resolver/src/candidate_selector.rs

@@ -196,8 +196,12 @@ impl CandidateSelector {
                 type Entries<'a> = SmallVec<[&'a Entry; 3]>;
 
                 let mut preferences = preferences.iter().collect::<Entries>();
+
                 // Filter out preferences that map to a conflicting index.
                 preferences.retain(|entry| index.is_none_or(|index| entry.index().matches(index)));
+
+                // Sort the preferences by priority.
+                let highest = self.use_highest_version(package_name, env);
                 preferences.sort_by_key(|entry| {
                     let marker = entry.marker();
 
@@ -207,8 +211,16 @@ impl CandidateSelector {
                     // Prefer preferences that match the current index.
                     let matches_index = index.is_none_or(|index| entry.index().matches(index));
 
-                    std::cmp::Reverse((matches_env, matches_index))
+                    // Prefer the latest (or earliest) version.
+                    let version = if highest {
+                        Either::Left(entry.pin().version())
+                    } else {
+                        Either::Right(std::cmp::Reverse(entry.pin().version()))
+                    };
+
+                    std::cmp::Reverse((matches_env, matches_index, version))
                 });
+
                 Either::Right(
                     preferences
                         .into_iter()

crates/uv/tests/it/export.rs

@@ -1243,11 +1243,10 @@ fn non_project_fork() -> Result<()> {
             source = { registry = "https://pypi.org/simple" }
             resolution-markers = [
                 "sys_platform == 'win32'",
-                "sys_platform != 'linux' and sys_platform != 'win32'",
             ]
             dependencies = [
-                { name = "idna", marker = "sys_platform != 'linux'" },
-                { name = "sniffio", marker = "sys_platform != 'linux'" },
+                { name = "idna", marker = "sys_platform == 'win32'" },
+                { name = "sniffio", marker = "sys_platform == 'win32'" },
             ]
             sdist = { url = "https://files.pythonhosted.org/packages/fe/dc/daeadb9b34093d3968afcc93946ee567cd6d2b402a96c608cb160f74d737/anyio-2.0.0.tar.gz", hash = "sha256:ceca4669ffa3f02bf20ef3d6c2a0c323b16cdc71d1ce0b0bc03c6f1f36054826", size = 91291 }
             wheels = [
@@ -1260,10 +1259,11 @@ fn non_project_fork() -> Result<()> {
             source = { registry = "https://pypi.org/simple" }
             resolution-markers = [
                 "sys_platform == 'linux'",
+                "sys_platform != 'linux' and sys_platform != 'win32'",
             ]
             dependencies = [
-                { name = "idna", marker = "sys_platform == 'linux'" },
-                { name = "sniffio", marker = "sys_platform == 'linux'" },
+                { name = "idna", marker = "sys_platform != 'win32'" },
+                { name = "sniffio", marker = "sys_platform != 'win32'" },
             ]
             sdist = { url = "https://files.pythonhosted.org/packages/99/0d/65165f99e5f4f3b4c43a5ed9db0fb7aa655f5a58f290727a30528a87eb45/anyio-3.0.0.tar.gz", hash = "sha256:b553598332c050af19f7d41f73a7790142f5bc3d5eb8bd82f5e515ec22019bd9", size = 116952 }
             wheels = [
@@ -1338,10 +1338,10 @@ fn non_project_fork() -> Result<()> {
     # This file was autogenerated by uv via the following command:
     #    uv export --cache-dir [CACHE_DIR] --group async
     -e ./child
-    anyio==2.0.0 ; sys_platform != 'linux' \
+    anyio==2.0.0 ; sys_platform == 'win32' \
         --hash=sha256:0b8375c8fc665236cb4d143ea13e849eb9e074d727b1b5c27d88aba44ca8c547 \
         --hash=sha256:ceca4669ffa3f02bf20ef3d6c2a0c323b16cdc71d1ce0b0bc03c6f1f36054826
-    anyio==3.0.0 ; sys_platform == 'linux' \
+    anyio==3.0.0 ; sys_platform != 'win32' \
         --hash=sha256:b553598332c050af19f7d41f73a7790142f5bc3d5eb8bd82f5e515ec22019bd9 \
         --hash=sha256:e71c3d9d72291d12056c0265d07c6bbedf92332f78573e278aeb116f24f30395
     idna==3.6 \
@@ -1361,10 +1361,10 @@ fn non_project_fork() -> Result<()> {
     ----- stdout -----
     # This file was autogenerated by uv via the following command:
     #    uv export --cache-dir [CACHE_DIR] --group async --prune child
-    anyio==2.0.0 ; sys_platform != 'linux' \
+    anyio==2.0.0 ; sys_platform == 'win32' \
         --hash=sha256:0b8375c8fc665236cb4d143ea13e849eb9e074d727b1b5c27d88aba44ca8c547 \
         --hash=sha256:ceca4669ffa3f02bf20ef3d6c2a0c323b16cdc71d1ce0b0bc03c6f1f36054826
-    anyio==3.0.0 ; sys_platform == 'linux' \
+    anyio==3.0.0 ; sys_platform != 'win32' \
         --hash=sha256:b553598332c050af19f7d41f73a7790142f5bc3d5eb8bd82f5e515ec22019bd9 \
         --hash=sha256:e71c3d9d72291d12056c0265d07c6bbedf92332f78573e278aeb116f24f30395
     idna==3.6 \

crates/uv/tests/it/lock_conflict.rs

@@ -4418,7 +4418,7 @@ conflicts = [
     Prepared 3 packages in [TIME]
     Installed 3 packages in [TIME]
      + anyio==4.3.0
-     + idna==3.5
+     + idna==3.6
      + sniffio==1.3.1
     "###);
 
@@ -4451,8 +4451,8 @@ conflicts = [
         source = { registry = "https://pypi.org/simple" }
         dependencies = [
             { name = "idna", version = "3.4", source = { registry = "https://pypi.org/simple" }, marker = "extra == 'extra-6-proxy1-x2' or (extra == 'extra-6-proxy1-x3' and extra == 'extra-7-project-x1')" },
-            { name = "idna", version = "3.5", source = { registry = "https://pypi.org/simple" }, marker = "extra == 'extra-6-proxy1-x3' or (extra == 'extra-6-proxy1-x2' and extra == 'extra-7-project-x1') or (extra != 'extra-6-proxy1-x2' and extra != 'extra-7-project-x1')" },
-            { name = "idna", version = "3.6", source = { registry = "https://pypi.org/simple" }, marker = "(extra == 'extra-6-proxy1-x2' and extra == 'extra-6-proxy1-x3') or (extra != 'extra-6-proxy1-x3' and extra == 'extra-7-project-x1') or (extra != 'extra-6-proxy1-x2' and extra == 'extra-7-project-x1')" },
+            { name = "idna", version = "3.5", source = { registry = "https://pypi.org/simple" }, marker = "extra == 'extra-6-proxy1-x3' or (extra == 'extra-6-proxy1-x2' and extra == 'extra-7-project-x1')" },
+            { name = "idna", version = "3.6", source = { registry = "https://pypi.org/simple" }, marker = "extra == 'extra-7-project-x1' or (extra == 'extra-6-proxy1-x2' and extra == 'extra-6-proxy1-x3') or (extra != 'extra-6-proxy1-x2' and extra != 'extra-6-proxy1-x3')" },
             { name = "sniffio" },
         ]
         sdist = { url = "https://files.pythonhosted.org/packages/db/4d/3970183622f0330d3c23d9b8a5f52e365e50381fd484d08e3285104333d3/anyio-4.3.0.tar.gz", hash = "sha256:f75253795a87df48568485fd18cdd2a3fa5c4f7c5be8e5e36637733fce06fed6", size = 159642 }

crates/uv/tests/it/pip_compile.rs

@@ -7906,7 +7906,7 @@ fn universal_disjoint_base_or_local_requirement() -> Result<()> {
     ----- stdout -----
     # This file was autogenerated by uv via the following command:
     #    uv pip compile --cache-dir [CACHE_DIR] requirements.in --universal
-    cmake==3.28.4 ; python_full_version >= '3.11' and python_full_version < '3.13' and platform_machine == 'x86_64' and sys_platform == 'linux'
+    cmake==3.28.4 ; python_full_version < '3.13' and platform_machine == 'x86_64' and sys_platform == 'linux'
         # via triton
     .
         # via -r requirements.in
@@ -7916,7 +7916,7 @@ fn universal_disjoint_base_or_local_requirement() -> Result<()> {
         #   triton
     jinja2==3.1.3
         # via torch
-    lit==18.1.2 ; python_full_version >= '3.11' and python_full_version < '3.13' and platform_machine == 'x86_64' and sys_platform == 'linux'
+    lit==18.1.2 ; python_full_version < '3.13' and platform_machine == 'x86_64' and sys_platform == 'linux'
         # via triton
     markupsafe==2.1.5
         # via jinja2
@@ -7930,16 +7930,16 @@ fn universal_disjoint_base_or_local_requirement() -> Result<()> {
         # via
         #   -r requirements.in
         #   example
-    torch==2.0.0+cpu ; python_full_version >= '3.13' or (python_full_version < '3.11' and platform_machine != 'aarch64' and sys_platform == 'linux') or (python_full_version < '3.11' and sys_platform != 'darwin' and sys_platform != 'linux')
+    torch==2.0.0+cpu ; python_full_version >= '3.13'
         # via
         #   -r requirements.in
         #   example
-    torch==2.0.0+cu118 ; python_full_version >= '3.11' and python_full_version < '3.13'
+    torch==2.0.0+cu118 ; (python_full_version >= '3.11' and python_full_version < '3.13' and sys_platform == 'darwin') or (python_full_version >= '3.11' and python_full_version < '3.13' and sys_platform == 'linux') or (python_full_version < '3.13' and platform_machine != 'aarch64' and sys_platform == 'linux') or (python_full_version < '3.13' and sys_platform != 'darwin' and sys_platform != 'linux')
         # via
         #   -r requirements.in
         #   example
         #   triton
-    triton==2.0.0 ; python_full_version >= '3.11' and python_full_version < '3.13' and platform_machine == 'x86_64' and sys_platform == 'linux'
+    triton==2.0.0 ; python_full_version < '3.13' and platform_machine == 'x86_64' and sys_platform == 'linux'
         # via torch
     typing-extensions==4.10.0
         # via torch
@@ -14430,3 +14430,62 @@ fn respect_index_preference() -> Result<()> {
 
     Ok(())
 }
+
+/// See: <https://github.com/astral-sh/uv/issues/10957>
+#[test]
+fn compile_preserve_requires_python_split() -> Result<()> {
+    static EXCLUDE_NEWER: &str = "2025-01-01T00:00:00Z";
+
+    let context = TestContext::new("3.8");
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str("zipp")?;
+
+    uv_snapshot!(context
+        .pip_compile()
+        .env(EnvVars::UV_EXCLUDE_NEWER, EXCLUDE_NEWER)
+        .arg("--python-version")
+        .arg("3.8")
+        .arg("--universal")
+        .arg("requirements.in")
+        .arg("-o")
+        .arg("requirements.txt"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] --python-version 3.8 --universal requirements.in -o requirements.txt
+    zipp==3.20.2 ; python_full_version < '3.9'
+        # via -r requirements.in
+    zipp==3.21.0 ; python_full_version >= '3.9'
+        # via -r requirements.in
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    "###);
+
+    // Re-running shouldn't change the output.
+    uv_snapshot!(context
+        .pip_compile()
+        .env(EnvVars::UV_EXCLUDE_NEWER, EXCLUDE_NEWER)
+        .arg("--python-version")
+        .arg("3.8")
+        .arg("--universal")
+        .arg("requirements.in")
+        .arg("-o")
+        .arg("requirements.txt"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] --python-version 3.8 --universal requirements.in -o requirements.txt
+    zipp==3.20.2 ; python_full_version < '3.9'
+        # via -r requirements.in
+    zipp==3.21.0 ; python_full_version >= '3.9'
+        # via -r requirements.in
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    "###);
+
+    Ok(())
+}