Improve type-name-incorrect-variance message (#5658)

## Summary Change the `type-name-incorrect-variance` diagnostic message to include the detected variance and a name change recommendation. For example, ``` `TypeVar` name "T_co" does not reflect its contravariance; consider renaming it to "T_contra" ``` Related to #5651. ## Test Plan `cargo test`
2023-07-10 18:33:37 +01:00
parent d19839fe0f
commit 5ab9538573
2 changed files with 92 additions and 44 deletions
--- a/crates/ruff/src/rules/pylint/rules/type_name_incorrect_variance.rs
+++ b/crates/ruff/src/rules/pylint/rules/type_name_incorrect_variance.rs
@@ -46,27 +46,34 @@ use crate::rules::pylint::helpers::type_param_name;
 pub struct TypeNameIncorrectVariance {
    kind: VarKind,
    param_name: String,
+    variance: VarVariance,
+    replacement_name: String,
 }

 impl Violation for TypeNameIncorrectVariance {
    #[derive_message_formats]
    fn message(&self) -> String {
-        let TypeNameIncorrectVariance { kind, param_name } = self;
-        format!("`{kind}` name \"{param_name}\" does not match variance")
+        let TypeNameIncorrectVariance {
+            kind,
+            param_name,
+            variance,
+            replacement_name,
+        } = self;
+        format!("`{kind}` name \"{param_name}\" does not reflect its {variance}; consider renaming it to \"{replacement_name}\"")
    }
 }

 /// PLC0105
 pub(crate) fn type_name_incorrect_variance(checker: &mut Checker, value: &Expr) {
    let Expr::Call(ast::ExprCall {
-        func,
-        args,
-        keywords,
-        ..
-    }) = value
-    else {
-        return;
-    };
+                       func,
+                       args,
+                       keywords,
+                       ..
+                   }) = value
+        else {
+            return;
+        };

    let Some(param_name) = type_param_name(args, keywords) else {
        return;
@@ -114,14 +121,26 @@ pub(crate) fn type_name_incorrect_variance(checker: &mut Checker, value: &Expr)
                None
            }
        })
-    else {
-        return;
+        else {
+            return;
+        };
+
+    let variance = variance(covariant, contravariant);
+    let name_root = param_name
+        .trim_end_matches("_co")
+        .trim_end_matches("_contra");
+    let replacement_name: String = match variance {
+        VarVariance::Covariance => format!("{name_root}_co"),
+        VarVariance::Contravariance => format!("{name_root}_contra"),
+        VarVariance::Invariance => name_root.to_string(),
    };

    checker.diagnostics.push(Diagnostic::new(
        TypeNameIncorrectVariance {
            kind,
            param_name: param_name.to_string(),
+            variance,
+            replacement_name,
        },
        func.range(),
    ));
@@ -138,6 +157,18 @@ fn mismatch(param_name: &str, covariant: Option<&Expr>, contravariant: Option<&E
    }
 }

+/// Return the variance of the type parameter.
+fn variance(covariant: Option<&Expr>, contravariant: Option<&Expr>) -> VarVariance {
+    match (
+        covariant.map(is_const_true),
+        contravariant.map(is_const_true),
+    ) {
+        (Some(true), _) => VarVariance::Covariance,
+        (_, Some(true)) => VarVariance::Contravariance,
+        _ => VarVariance::Invariance,
+    }
+}
+
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 enum VarKind {
    TypeVar,
@@ -152,3 +183,20 @@ impl fmt::Display for VarKind {
        }
    }
 }
+
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+enum VarVariance {
+    Covariance,
+    Contravariance,
+    Invariance,
+}
+
+impl fmt::Display for VarVariance {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            VarVariance::Covariance => fmt.write_str("covariance"),
+            VarVariance::Contravariance => fmt.write_str("contravariance"),
+            VarVariance::Invariance => fmt.write_str("invariance"),
+        }
+    }
+}
--- a/crates/ruff/src/rules/pylint/snapshots/ruffrulespylinttestsPLC0105_type_name_incorrect_variance.py.snap
+++ b/crates/ruff/src/rules/pylint/snapshots/ruffrulespylinttestsPLC0105_type_name_incorrect_variance.py.snap
@@ -1,7 +1,7 @@
 ---
 source: crates/ruff/src/rules/pylint/mod.rs
 ---
-type_name_incorrect_variance.py:5:5: PLC0105 `TypeVar` name "T" does not match variance
+type_name_incorrect_variance.py:5:5: PLC0105 `TypeVar` name "T" does not reflect its covariance; consider renaming it to "T_co"
  |
 3 | # Errors.
 4 | 
@@ -11,7 +11,7 @@ type_name_incorrect_variance.py:5:5: PLC0105 `TypeVar` name "T" does not match v
 7 | T = TypeVar("T", contravariant=True)
  |

-type_name_incorrect_variance.py:6:5: PLC0105 `TypeVar` name "T" does not match variance
+type_name_incorrect_variance.py:6:5: PLC0105 `TypeVar` name "T" does not reflect its covariance; consider renaming it to "T_co"
  |
 5 | T = TypeVar("T", covariant=True)
 6 | T = TypeVar("T", covariant=True, contravariant=False)
@@ -20,7 +20,7 @@ type_name_incorrect_variance.py:6:5: PLC0105 `TypeVar` name "T" does not match v
 8 | T = TypeVar("T", covariant=False, contravariant=True)
  |

-type_name_incorrect_variance.py:7:5: PLC0105 `TypeVar` name "T" does not match variance
+type_name_incorrect_variance.py:7:5: PLC0105 `TypeVar` name "T" does not reflect its contravariance; consider renaming it to "T_contra"
  |
 5 | T = TypeVar("T", covariant=True)
 6 | T = TypeVar("T", covariant=True, contravariant=False)
@@ -30,7 +30,7 @@ type_name_incorrect_variance.py:7:5: PLC0105 `TypeVar` name "T" does not match v
 9 | P = ParamSpec("P", covariant=True)
  |

-type_name_incorrect_variance.py:8:5: PLC0105 `TypeVar` name "T" does not match variance
+type_name_incorrect_variance.py:8:5: PLC0105 `TypeVar` name "T" does not reflect its contravariance; consider renaming it to "T_contra"
   |
 6 | T = TypeVar("T", covariant=True, contravariant=False)
 7 | T = TypeVar("T", contravariant=True)
@@ -40,7 +40,7 @@ type_name_incorrect_variance.py:8:5: PLC0105 `TypeVar` name "T" does not match v
 10 | P = ParamSpec("P", covariant=True, contravariant=False)
   |

-type_name_incorrect_variance.py:9:5: PLC0105 `ParamSpec` name "P" does not match variance
+type_name_incorrect_variance.py:9:5: PLC0105 `ParamSpec` name "P" does not reflect its covariance; consider renaming it to "P_co"
   |
 7 | T = TypeVar("T", contravariant=True)
 8 | T = TypeVar("T", covariant=False, contravariant=True)
@@ -50,7 +50,7 @@ type_name_incorrect_variance.py:9:5: PLC0105 `ParamSpec` name "P" does not match
 11 | P = ParamSpec("P", contravariant=True)
   |

-type_name_incorrect_variance.py:10:5: PLC0105 `ParamSpec` name "P" does not match variance
+type_name_incorrect_variance.py:10:5: PLC0105 `ParamSpec` name "P" does not reflect its covariance; consider renaming it to "P_co"
   |
 8 | T = TypeVar("T", covariant=False, contravariant=True)
 9 | P = ParamSpec("P", covariant=True)
@@ -60,7 +60,7 @@ type_name_incorrect_variance.py:10:5: PLC0105 `ParamSpec` name "P" does not matc
 12 | P = ParamSpec("P", covariant=False, contravariant=True)
   |

-type_name_incorrect_variance.py:11:5: PLC0105 `ParamSpec` name "P" does not match variance
+type_name_incorrect_variance.py:11:5: PLC0105 `ParamSpec` name "P" does not reflect its contravariance; consider renaming it to "P_contra"
   |
 9 | P = ParamSpec("P", covariant=True)
 10 | P = ParamSpec("P", covariant=True, contravariant=False)
@@ -69,7 +69,7 @@ type_name_incorrect_variance.py:11:5: PLC0105 `ParamSpec` name "P" does not matc
 12 | P = ParamSpec("P", covariant=False, contravariant=True)
   |

-type_name_incorrect_variance.py:12:5: PLC0105 `ParamSpec` name "P" does not match variance
+type_name_incorrect_variance.py:12:5: PLC0105 `ParamSpec` name "P" does not reflect its contravariance; consider renaming it to "P_contra"
   |
 10 | P = ParamSpec("P", covariant=True, contravariant=False)
 11 | P = ParamSpec("P", contravariant=True)
@@ -79,7 +79,7 @@ type_name_incorrect_variance.py:12:5: PLC0105 `ParamSpec` name "P" does not matc
 14 | T_co = TypeVar("T_co")
   |

-type_name_incorrect_variance.py:14:8: PLC0105 `TypeVar` name "T_co" does not match variance
+type_name_incorrect_variance.py:14:8: PLC0105 `TypeVar` name "T_co" does not reflect its invariance; consider renaming it to "T"
   |
 12 | P = ParamSpec("P", covariant=False, contravariant=True)
 13 | 
@@ -89,7 +89,7 @@ type_name_incorrect_variance.py:14:8: PLC0105 `TypeVar` name "T_co" does not mat
 16 | T_co = TypeVar("T_co", contravariant=False)
   |

-type_name_incorrect_variance.py:15:8: PLC0105 `TypeVar` name "T_co" does not match variance
+type_name_incorrect_variance.py:15:8: PLC0105 `TypeVar` name "T_co" does not reflect its invariance; consider renaming it to "T"
   |
 14 | T_co = TypeVar("T_co")
 15 | T_co = TypeVar("T_co", covariant=False)
@@ -98,7 +98,7 @@ type_name_incorrect_variance.py:15:8: PLC0105 `TypeVar` name "T_co" does not mat
 17 | T_co = TypeVar("T_co", covariant=False, contravariant=False)
   |

-type_name_incorrect_variance.py:16:8: PLC0105 `TypeVar` name "T_co" does not match variance
+type_name_incorrect_variance.py:16:8: PLC0105 `TypeVar` name "T_co" does not reflect its invariance; consider renaming it to "T"
   |
 14 | T_co = TypeVar("T_co")
 15 | T_co = TypeVar("T_co", covariant=False)
@@ -108,7 +108,7 @@ type_name_incorrect_variance.py:16:8: PLC0105 `TypeVar` name "T_co" does not mat
 18 | T_co = TypeVar("T_co", contravariant=True)
   |

-type_name_incorrect_variance.py:17:8: PLC0105 `TypeVar` name "T_co" does not match variance
+type_name_incorrect_variance.py:17:8: PLC0105 `TypeVar` name "T_co" does not reflect its invariance; consider renaming it to "T"
   |
 15 | T_co = TypeVar("T_co", covariant=False)
 16 | T_co = TypeVar("T_co", contravariant=False)
@@ -118,7 +118,7 @@ type_name_incorrect_variance.py:17:8: PLC0105 `TypeVar` name "T_co" does not mat
 19 | T_co = TypeVar("T_co", covariant=False, contravariant=True)
   |

-type_name_incorrect_variance.py:18:8: PLC0105 `TypeVar` name "T_co" does not match variance
+type_name_incorrect_variance.py:18:8: PLC0105 `TypeVar` name "T_co" does not reflect its contravariance; consider renaming it to "T_contra"
   |
 16 | T_co = TypeVar("T_co", contravariant=False)
 17 | T_co = TypeVar("T_co", covariant=False, contravariant=False)
@@ -128,7 +128,7 @@ type_name_incorrect_variance.py:18:8: PLC0105 `TypeVar` name "T_co" does not mat
 20 | P_co = ParamSpec("P_co")
   |

-type_name_incorrect_variance.py:19:8: PLC0105 `TypeVar` name "T_co" does not match variance
+type_name_incorrect_variance.py:19:8: PLC0105 `TypeVar` name "T_co" does not reflect its contravariance; consider renaming it to "T_contra"
   |
 17 | T_co = TypeVar("T_co", covariant=False, contravariant=False)
 18 | T_co = TypeVar("T_co", contravariant=True)
@@ -138,7 +138,7 @@ type_name_incorrect_variance.py:19:8: PLC0105 `TypeVar` name "T_co" does not mat
 21 | P_co = ParamSpec("P_co", covariant=False)
   |

-type_name_incorrect_variance.py:20:8: PLC0105 `ParamSpec` name "P_co" does not match variance
+type_name_incorrect_variance.py:20:8: PLC0105 `ParamSpec` name "P_co" does not reflect its invariance; consider renaming it to "P"
   |
 18 | T_co = TypeVar("T_co", contravariant=True)
 19 | T_co = TypeVar("T_co", covariant=False, contravariant=True)
@@ -148,7 +148,7 @@ type_name_incorrect_variance.py:20:8: PLC0105 `ParamSpec` name "P_co" does not m
 22 | P_co = ParamSpec("P_co", contravariant=False)
   |

-type_name_incorrect_variance.py:21:8: PLC0105 `ParamSpec` name "P_co" does not match variance
+type_name_incorrect_variance.py:21:8: PLC0105 `ParamSpec` name "P_co" does not reflect its invariance; consider renaming it to "P"
   |
 19 | T_co = TypeVar("T_co", covariant=False, contravariant=True)
 20 | P_co = ParamSpec("P_co")
@@ -158,7 +158,7 @@ type_name_incorrect_variance.py:21:8: PLC0105 `ParamSpec` name "P_co" does not m
 23 | P_co = ParamSpec("P_co", covariant=False, contravariant=False)
   |

-type_name_incorrect_variance.py:22:8: PLC0105 `ParamSpec` name "P_co" does not match variance
+type_name_incorrect_variance.py:22:8: PLC0105 `ParamSpec` name "P_co" does not reflect its invariance; consider renaming it to "P"
   |
 20 | P_co = ParamSpec("P_co")
 21 | P_co = ParamSpec("P_co", covariant=False)
@@ -168,7 +168,7 @@ type_name_incorrect_variance.py:22:8: PLC0105 `ParamSpec` name "P_co" does not m
 24 | P_co = ParamSpec("P_co", contravariant=True)
   |

-type_name_incorrect_variance.py:23:8: PLC0105 `ParamSpec` name "P_co" does not match variance
+type_name_incorrect_variance.py:23:8: PLC0105 `ParamSpec` name "P_co" does not reflect its invariance; consider renaming it to "P"
   |
 21 | P_co = ParamSpec("P_co", covariant=False)
 22 | P_co = ParamSpec("P_co", contravariant=False)
@@ -178,7 +178,7 @@ type_name_incorrect_variance.py:23:8: PLC0105 `ParamSpec` name "P_co" does not m
 25 | P_co = ParamSpec("P_co", covariant=False, contravariant=True)
   |

-type_name_incorrect_variance.py:24:8: PLC0105 `ParamSpec` name "P_co" does not match variance
+type_name_incorrect_variance.py:24:8: PLC0105 `ParamSpec` name "P_co" does not reflect its contravariance; consider renaming it to "P_contra"
   |
 22 | P_co = ParamSpec("P_co", contravariant=False)
 23 | P_co = ParamSpec("P_co", covariant=False, contravariant=False)
@@ -187,7 +187,7 @@ type_name_incorrect_variance.py:24:8: PLC0105 `ParamSpec` name "P_co" does not m
 25 | P_co = ParamSpec("P_co", covariant=False, contravariant=True)
   |

-type_name_incorrect_variance.py:25:8: PLC0105 `ParamSpec` name "P_co" does not match variance
+type_name_incorrect_variance.py:25:8: PLC0105 `ParamSpec` name "P_co" does not reflect its contravariance; consider renaming it to "P_contra"
   |
 23 | P_co = ParamSpec("P_co", covariant=False, contravariant=False)
 24 | P_co = ParamSpec("P_co", contravariant=True)
@@ -197,7 +197,7 @@ type_name_incorrect_variance.py:25:8: PLC0105 `ParamSpec` name "P_co" does not m
 27 | T_contra = TypeVar("T_contra")
   |

-type_name_incorrect_variance.py:27:12: PLC0105 `TypeVar` name "T_contra" does not match variance
+type_name_incorrect_variance.py:27:12: PLC0105 `TypeVar` name "T_contra" does not reflect its invariance; consider renaming it to "T"
   |
 25 | P_co = ParamSpec("P_co", covariant=False, contravariant=True)
 26 | 
@@ -207,7 +207,7 @@ type_name_incorrect_variance.py:27:12: PLC0105 `TypeVar` name "T_contra" does no
 29 | T_contra = TypeVar("T_contra", contravariant=False)
   |

-type_name_incorrect_variance.py:28:12: PLC0105 `TypeVar` name "T_contra" does not match variance
+type_name_incorrect_variance.py:28:12: PLC0105 `TypeVar` name "T_contra" does not reflect its invariance; consider renaming it to "T"
   |
 27 | T_contra = TypeVar("T_contra")
 28 | T_contra = TypeVar("T_contra", covariant=False)
@@ -216,7 +216,7 @@ type_name_incorrect_variance.py:28:12: PLC0105 `TypeVar` name "T_contra" does no
 30 | T_contra = TypeVar("T_contra", covariant=False, contravariant=False)
   |

-type_name_incorrect_variance.py:29:12: PLC0105 `TypeVar` name "T_contra" does not match variance
+type_name_incorrect_variance.py:29:12: PLC0105 `TypeVar` name "T_contra" does not reflect its invariance; consider renaming it to "T"
   |
 27 | T_contra = TypeVar("T_contra")
 28 | T_contra = TypeVar("T_contra", covariant=False)
@@ -226,7 +226,7 @@ type_name_incorrect_variance.py:29:12: PLC0105 `TypeVar` name "T_contra" does no
 31 | T_contra = TypeVar("T_contra", covariant=True)
   |

-type_name_incorrect_variance.py:30:12: PLC0105 `TypeVar` name "T_contra" does not match variance
+type_name_incorrect_variance.py:30:12: PLC0105 `TypeVar` name "T_contra" does not reflect its invariance; consider renaming it to "T"
   |
 28 | T_contra = TypeVar("T_contra", covariant=False)
 29 | T_contra = TypeVar("T_contra", contravariant=False)
@@ -236,7 +236,7 @@ type_name_incorrect_variance.py:30:12: PLC0105 `TypeVar` name "T_contra" does no
 32 | T_contra = TypeVar("T_contra", covariant=True, contravariant=False)
   |

-type_name_incorrect_variance.py:31:12: PLC0105 `TypeVar` name "T_contra" does not match variance
+type_name_incorrect_variance.py:31:12: PLC0105 `TypeVar` name "T_contra" does not reflect its covariance; consider renaming it to "T_co"
   |
 29 | T_contra = TypeVar("T_contra", contravariant=False)
 30 | T_contra = TypeVar("T_contra", covariant=False, contravariant=False)
@@ -246,7 +246,7 @@ type_name_incorrect_variance.py:31:12: PLC0105 `TypeVar` name "T_contra" does no
 33 | P_contra = ParamSpec("P_contra")
   |

-type_name_incorrect_variance.py:32:12: PLC0105 `TypeVar` name "T_contra" does not match variance
+type_name_incorrect_variance.py:32:12: PLC0105 `TypeVar` name "T_contra" does not reflect its covariance; consider renaming it to "T_co"
   |
 30 | T_contra = TypeVar("T_contra", covariant=False, contravariant=False)
 31 | T_contra = TypeVar("T_contra", covariant=True)
@@ -256,7 +256,7 @@ type_name_incorrect_variance.py:32:12: PLC0105 `TypeVar` name "T_contra" does no
 34 | P_contra = ParamSpec("P_contra", covariant=False)
   |

-type_name_incorrect_variance.py:33:12: PLC0105 `ParamSpec` name "P_contra" does not match variance
+type_name_incorrect_variance.py:33:12: PLC0105 `ParamSpec` name "P_contra" does not reflect its invariance; consider renaming it to "P"
   |
 31 | T_contra = TypeVar("T_contra", covariant=True)
 32 | T_contra = TypeVar("T_contra", covariant=True, contravariant=False)
@@ -266,7 +266,7 @@ type_name_incorrect_variance.py:33:12: PLC0105 `ParamSpec` name "P_contra" does
 35 | P_contra = ParamSpec("P_contra", contravariant=False)
   |

-type_name_incorrect_variance.py:34:12: PLC0105 `ParamSpec` name "P_contra" does not match variance
+type_name_incorrect_variance.py:34:12: PLC0105 `ParamSpec` name "P_contra" does not reflect its invariance; consider renaming it to "P"
   |
 32 | T_contra = TypeVar("T_contra", covariant=True, contravariant=False)
 33 | P_contra = ParamSpec("P_contra")
@@ -276,7 +276,7 @@ type_name_incorrect_variance.py:34:12: PLC0105 `ParamSpec` name "P_contra" does
 36 | P_contra = ParamSpec("P_contra", covariant=False, contravariant=False)
   |

-type_name_incorrect_variance.py:35:12: PLC0105 `ParamSpec` name "P_contra" does not match variance
+type_name_incorrect_variance.py:35:12: PLC0105 `ParamSpec` name "P_contra" does not reflect its invariance; consider renaming it to "P"
   |
 33 | P_contra = ParamSpec("P_contra")
 34 | P_contra = ParamSpec("P_contra", covariant=False)
@@ -286,7 +286,7 @@ type_name_incorrect_variance.py:35:12: PLC0105 `ParamSpec` name "P_contra" does
 37 | P_contra = ParamSpec("P_contra", covariant=True)
   |

-type_name_incorrect_variance.py:36:12: PLC0105 `ParamSpec` name "P_contra" does not match variance
+type_name_incorrect_variance.py:36:12: PLC0105 `ParamSpec` name "P_contra" does not reflect its invariance; consider renaming it to "P"
   |
 34 | P_contra = ParamSpec("P_contra", covariant=False)
 35 | P_contra = ParamSpec("P_contra", contravariant=False)
@@ -296,7 +296,7 @@ type_name_incorrect_variance.py:36:12: PLC0105 `ParamSpec` name "P_contra" does
 38 | P_contra = ParamSpec("P_contra", covariant=True, contravariant=False)
   |

-type_name_incorrect_variance.py:37:12: PLC0105 `ParamSpec` name "P_contra" does not match variance
+type_name_incorrect_variance.py:37:12: PLC0105 `ParamSpec` name "P_contra" does not reflect its covariance; consider renaming it to "P_co"
   |
 35 | P_contra = ParamSpec("P_contra", contravariant=False)
 36 | P_contra = ParamSpec("P_contra", covariant=False, contravariant=False)
@@ -305,7 +305,7 @@ type_name_incorrect_variance.py:37:12: PLC0105 `ParamSpec` name "P_contra" does
 38 | P_contra = ParamSpec("P_contra", covariant=True, contravariant=False)
   |

-type_name_incorrect_variance.py:38:12: PLC0105 `ParamSpec` name "P_contra" does not match variance
+type_name_incorrect_variance.py:38:12: PLC0105 `ParamSpec` name "P_contra" does not reflect its covariance; consider renaming it to "P_co"
   |
 36 | P_contra = ParamSpec("P_contra", covariant=False, contravariant=False)
 37 | P_contra = ParamSpec("P_contra", covariant=True)