Warn when requires-python patch version isn't specified

Warn when requires-python is set to an exact value (==) and doesn't include a patch (so it'll get set to 0)

crates/uv-resolver/Cargo.toml

@@ -63,3 +63,4 @@ url = { workspace = true }
 [dev-dependencies]
 insta = { version = "1.40.0" }
 toml = { workspace = true }
+test-case = { version = "3.3.1" }

crates/uv-resolver/src/requires_python.rs

@@ -266,6 +266,18 @@ impl RequiresPython {
         self.range.lower().as_ref() == Bound::Unbounded
     }
 
+    /// Returns `true` if the `Requires-Python` specifier is set to a specific version
+    /// without a patch version. (e.g. `==3.10`)
+    pub fn is_matching_without_patch(&self) -> bool {
+        match self.range.lower().as_ref() {
+            Bound::Included(version) => {
+                version.release().len() == 2
+                    && self.range.upper().as_ref() == Bound::Included(version)
+            }
+            _ => false,
+        }
+    }
+
     /// Returns the [`RequiresPythonBound`] truncated to the major and minor version.
     pub fn bound_major_minor(&self) -> LowerBound {
         match self.range.lower().as_ref() {
@@ -711,6 +723,7 @@ mod tests {
     use std::cmp::Ordering;
     use std::collections::Bound;
     use std::str::FromStr;
+    use test_case::test_case;
 
     use uv_distribution_filename::WheelFilename;
     use uv_pep440::{Version, VersionSpecifiers};
@@ -820,4 +833,20 @@ mod tests {
             }
         }
     }
+
+    #[test_case("==3.12", true)]
+    #[test_case("==2.7", true)]
+    #[test_case("==3.12.1", false)]
+    #[test_case("==3.12.*", false)]
+    #[test_case("==3.*", false)]
+    #[test_case(">=3.10", false)]
+    #[test_case(">3.9", false)]
+    #[test_case("<4.0", false)]
+    #[test_case(">=3.10, <3.11", false)]
+    #[test_case("", false)]
+    fn is_matching_without_patch(version: &str, expected: bool) {
+        let version_specifiers = VersionSpecifiers::from_str(version).unwrap();
+        let requires_python = RequiresPython::from_specifiers(&version_specifiers).unwrap();
+        assert_eq!(requires_python.is_matching_without_patch(), expected);
+    }
 }

crates/uv/src/commands/project/lock.rs

@@ -334,6 +334,8 @@ async fn do_lock(
             let default =
                 RequiresPython::greater_than_equal_version(&interpreter.python_minor_version());
             warn_user_once!("The workspace `requires-python` value does not contain a lower bound: `{requires_python}`. Set a lower bound to indicate the minimum compatible Python version (e.g., `{default}`).");
+        } else if requires_python.is_matching_without_patch() {
+            warn_user_once!("The workspace `requires-python` value is a matching reference without a patch version: `{requires_python}`. It will be interpreted as `{requires_python}.0`. Did you mean `{requires_python}.*`?");
         }
         requires_python
     } else {