Rename applicability levels to always, sometimes, and never (#7821)

Following much discussion for #4181 at
#5119,
#5476, #7769,
#7819, and in
[Discord](https://discord.com/channels/1039017663004942429/1082324250112823306/1159144114231709746),
this pull request changes `Applicability` from using `Automatic`,
`Suggested`, and `Manual` to `Always`, `Sometimes`, and `Never`.

Also removes `Applicability::Unspecified` (replacing #7792).

crates/ruff_cli/tests/format.rs

@@ -175,7 +175,7 @@ import os
         },
         "filename": "-",
         "fix": {
-          "applicability": "Automatic",
+          "applicability": "always",
           "edits": [
             {
               "content": "",

crates/ruff_cli/tests/snapshots/integration_test__stdin_json.snap

@@ -24,7 +24,7 @@ exit_code: 1
     },
     "filename": "/path/to/F401.py",
     "fix": {
-      "applicability": "Automatic",
+      "applicability": "always",
       "edits": [
         {
           "content": "",

crates/ruff_diagnostics/src/fix.rs

@@ -5,27 +5,22 @@ use ruff_text_size::{Ranged, TextSize};
 
 use crate::edit::Edit;
 
-/// Indicates confidence in the correctness of a suggested fix.
-#[derive(Default, Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
+/// Indicates if a fix can be applied.
+#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "serde", serde(rename_all = "lowercase"))]
 pub enum Applicability {
-    /// The fix is definitely what the user intended, or maintains the exact meaning of the code.
-    /// This fix should be automatically applied.
-    Automatic,
-
-    /// The fix may be what the user intended, but it is uncertain.
-    /// The fix should result in valid code if it is applied.
-    /// The fix can be applied with user opt-in.
-    Suggested,
+    /// The fix is safe and can always be applied.
+    /// The fix is definitely what the user intended, or it maintains the exact meaning of the code.
+    Always,
 
-    /// The fix has a good chance of being incorrect or the code be incomplete.
-    /// The fix may result in invalid code if it is applied.
-    /// The fix should only be manually applied by the user.
-    Manual,
+    /// The fix is unsafe and should only be applied with user opt-in.
+    /// The fix may be what the user intended, but it is uncertain; the resulting code will have valid syntax.
+    Sometimes,
 
-    /// The applicability of the fix is unknown.
-    #[default]
-    Unspecified,
+    /// The fix is unsafe and should only be manually applied by the user.
+    /// The fix is likely to be incorrect or the resulting code may have invalid syntax.
+    Never,
 }
 
 /// Indicates the level of isolation required to apply a fix.
@@ -52,86 +47,62 @@ pub struct Fix {
 }
 
 impl Fix {
-    /// Create a new [`Fix`] with an unspecified applicability from an [`Edit`] element.
-    #[deprecated(
-        note = "Use `Fix::automatic`, `Fix::suggested`, or `Fix::manual` instead to specify an applicability."
-    )]
-    pub fn unspecified(edit: Edit) -> Self {
-        Self {
-            edits: vec![edit],
-            applicability: Applicability::Unspecified,
-            isolation_level: IsolationLevel::default(),
-        }
-    }
-
-    /// Create a new [`Fix`] with an unspecified applicability from multiple [`Edit`] elements.
-    #[deprecated(
-        note = "Use `Fix::automatic_edits`, `Fix::suggested_edits`, or `Fix::manual_edits` instead to specify an applicability."
-    )]
-    pub fn unspecified_edits(edit: Edit, rest: impl IntoIterator<Item = Edit>) -> Self {
-        Self {
-            edits: std::iter::once(edit).chain(rest).collect(),
-            applicability: Applicability::Unspecified,
-            isolation_level: IsolationLevel::default(),
-        }
-    }
-
-    /// Create a new [`Fix`] with [automatic applicability](Applicability::Automatic) from an [`Edit`] element.
-    pub fn automatic(edit: Edit) -> Self {
+    /// Create a new [`Fix`] that can [always](Applicability::Always) be applied from an [`Edit`] element.
+    pub fn always_applies(edit: Edit) -> Self {
         Self {
             edits: vec![edit],
-            applicability: Applicability::Automatic,
+            applicability: Applicability::Always,
             isolation_level: IsolationLevel::default(),
         }
     }
 
-    /// Create a new [`Fix`] with [automatic applicability](Applicability::Automatic) from multiple [`Edit`] elements.
-    pub fn automatic_edits(edit: Edit, rest: impl IntoIterator<Item = Edit>) -> Self {
+    /// Create a new [`Fix`] that can [always](Applicability::Always) be applied from multiple [`Edit`] elements.
+    pub fn always_applies_edits(edit: Edit, rest: impl IntoIterator<Item = Edit>) -> Self {
         let mut edits: Vec<Edit> = std::iter::once(edit).chain(rest).collect();
         edits.sort_by_key(|edit| (edit.start(), edit.end()));
         Self {
             edits,
-            applicability: Applicability::Automatic,
+            applicability: Applicability::Always,
             isolation_level: IsolationLevel::default(),
         }
     }
 
-    /// Create a new [`Fix`] with [suggested applicability](Applicability::Suggested) from an [`Edit`] element.
-    pub fn suggested(edit: Edit) -> Self {
+    /// Create a new [`Fix`] that can [sometimes](Applicability::Sometimes) be applied from an [`Edit`] element.
+    pub fn sometimes_applies(edit: Edit) -> Self {
         Self {
             edits: vec![edit],
-            applicability: Applicability::Suggested,
+            applicability: Applicability::Sometimes,
             isolation_level: IsolationLevel::default(),
         }
     }
 
-    /// Create a new [`Fix`] with [suggested applicability](Applicability::Suggested) from multiple [`Edit`] elements.
-    pub fn suggested_edits(edit: Edit, rest: impl IntoIterator<Item = Edit>) -> Self {
+    /// Create a new [`Fix`] that can [sometimes](Applicability::Sometimes) be applied from multiple [`Edit`] elements.
+    pub fn sometimes_applies_edits(edit: Edit, rest: impl IntoIterator<Item = Edit>) -> Self {
         let mut edits: Vec<Edit> = std::iter::once(edit).chain(rest).collect();
         edits.sort_by_key(|edit| (edit.start(), edit.end()));
         Self {
             edits,
-            applicability: Applicability::Suggested,
+            applicability: Applicability::Sometimes,
             isolation_level: IsolationLevel::default(),
         }
     }
 
-    /// Create a new [`Fix`] with [manual applicability](Applicability::Manual) from an [`Edit`] element.
-    pub fn manual(edit: Edit) -> Self {
+    /// Create a new [`Fix`] that should [never](Applicability::Never) be applied from an [`Edit`] element .
+    pub fn never_applies(edit: Edit) -> Self {
         Self {
             edits: vec![edit],
-            applicability: Applicability::Manual,
+            applicability: Applicability::Never,
             isolation_level: IsolationLevel::default(),
         }
     }
 
-    /// Create a new [`Fix`] with [manual applicability](Applicability::Manual) from multiple [`Edit`] elements.
-    pub fn manual_edits(edit: Edit, rest: impl IntoIterator<Item = Edit>) -> Self {
+    /// Create a new [`Fix`] that should [never](Applicability::Never) be applied from multiple [`Edit`] elements.
+    pub fn never_applies_edits(edit: Edit, rest: impl IntoIterator<Item = Edit>) -> Self {
         let mut edits: Vec<Edit> = std::iter::once(edit).chain(rest).collect();
         edits.sort_by_key(|edit| (edit.start(), edit.end()));
         Self {
             edits,
-            applicability: Applicability::Manual,
+            applicability: Applicability::Never,
             isolation_level: IsolationLevel::default(),
         }
     }

crates/ruff_linter/src/checkers/ast/analyze/bindings.rs

@@ -38,7 +38,7 @@ pub(crate) fn bindings(checker: &mut Checker) {
                             binding,
                             checker.locator,
                         )
-                        .map(Fix::automatic)
+                        .map(Fix::always_applies)
                     });
                 }
                 checker.diagnostics.push(diagnostic);

crates/ruff_linter/src/checkers/noqa.rs

@@ -110,8 +110,10 @@ pub(crate) fn check_noqa(
                         let mut diagnostic =
                             Diagnostic::new(UnusedNOQA { codes: None }, directive.range());
                         if settings.rules.should_fix(diagnostic.kind.rule()) {
-                            diagnostic
-                                .set_fix(Fix::suggested(delete_noqa(directive.range(), locator)));
+                            diagnostic.set_fix(Fix::sometimes_applies(delete_noqa(
+                                directive.range(),
+                                locator,
+                            )));
                         }
                         diagnostics.push(diagnostic);
                     }
@@ -175,15 +177,17 @@ pub(crate) fn check_noqa(
                         );
                         if settings.rules.should_fix(diagnostic.kind.rule()) {
                             if valid_codes.is_empty() {
-                                diagnostic.set_fix(Fix::suggested(delete_noqa(
+                                diagnostic.set_fix(Fix::sometimes_applies(delete_noqa(
                                     directive.range(),
                                     locator,
                                 )));
                             } else {
-                                diagnostic.set_fix(Fix::suggested(Edit::range_replacement(
-                                    format!("# noqa: {}", valid_codes.join(", ")),
-                                    directive.range(),
-                                )));
+                                diagnostic.set_fix(Fix::sometimes_applies(
+                                    Edit::range_replacement(
+                                        format!("# noqa: {}", valid_codes.join(", ")),
+                                        directive.range(),
+                                    ),
+                                ));
                             }
                         }
                         diagnostics.push(diagnostic);

crates/ruff_linter/src/fix/mod.rs

@@ -151,7 +151,7 @@ mod tests {
                 // The choice of rule here is arbitrary.
                 kind: MissingNewlineAtEndOfFile.into(),
                 range: edit.range(),
-                fix: Some(Fix::unspecified(edit)),
+                fix: Some(Fix::always_applies(edit)),
                 parent: None,
             })
             .collect()

crates/ruff_linter/src/message/diff.rs

@@ -52,10 +52,10 @@ impl Display for Diff<'_> {
         let diff = TextDiff::from_lines(self.source_code.source_text(), &output);
 
         let message = match self.fix.applicability() {
-            Applicability::Automatic => "Fix",
-            Applicability::Suggested => "Suggested fix",
-            Applicability::Manual => "Possible fix",
-            Applicability::Unspecified => "Suggested fix", /* For backwards compatibility, unspecified fixes are 'suggested' */
+            // TODO(zanieb): Adjust this messaging once it's user-facing
+            Applicability::Always => "Fix",
+            Applicability::Sometimes => "Suggested fix",
+            Applicability::Never => "Possible fix",
         };
         writeln!(f, "ℹ {}", message.blue())?;
 

crates/ruff_linter/src/message/mod.rs

@@ -178,10 +178,9 @@ def fibonacci(n):
             },
             TextRange::new(TextSize::from(7), TextSize::from(9)),
         )
-        .with_fix(Fix::suggested(Edit::range_deletion(TextRange::new(
-            TextSize::from(0),
-            TextSize::from(10),
-        ))));
+        .with_fix(Fix::sometimes_applies(Edit::range_deletion(
+            TextRange::new(TextSize::from(0), TextSize::from(10)),
+        )));
 
         let fib_source = SourceFileBuilder::new("fib.py", fib).finish();
 
@@ -193,7 +192,7 @@ def fibonacci(n):
             },
             TextRange::new(TextSize::from(94), TextSize::from(95)),
         )
-        .with_fix(Fix::suggested(Edit::deletion(
+        .with_fix(Fix::sometimes_applies(Edit::deletion(
             TextSize::from(94),
             TextSize::from(99),
         )));

crates/ruff_linter/src/message/snapshots/ruff_linter__message__json__tests__output.snap

@@ -11,7 +11,7 @@ expression: content
     },
     "filename": "fib.py",
     "fix": {
-      "applicability": "Suggested",
+      "applicability": "sometimes",
       "edits": [
         {
           "content": "",
@@ -43,7 +43,7 @@ expression: content
     },
     "filename": "fib.py",
     "fix": {
-      "applicability": "Suggested",
+      "applicability": "sometimes",
       "edits": [
         {
           "content": "",

crates/ruff_linter/src/message/snapshots/ruff_linter__message__json_lines__tests__output.snap

@@ -2,7 +2,7 @@
 source: crates/ruff_linter/src/message/json_lines.rs
 expression: content
 ---
-{"code":"F401","end_location":{"column":10,"row":1},"filename":"fib.py","fix":{"applicability":"Suggested","edits":[{"content":"","end_location":{"column":1,"row":2},"location":{"column":1,"row":1}}],"message":"Remove unused import: `os`"},"location":{"column":8,"row":1},"message":"`os` imported but unused","noqa_row":1,"url":"https://docs.astral.sh/ruff/rules/unused-import"}
-{"code":"F841","end_location":{"column":6,"row":6},"filename":"fib.py","fix":{"applicability":"Suggested","edits":[{"content":"","end_location":{"column":10,"row":6},"location":{"column":5,"row":6}}],"message":"Remove assignment to unused variable `x`"},"location":{"column":5,"row":6},"message":"Local variable `x` is assigned to but never used","noqa_row":6,"url":"https://docs.astral.sh/ruff/rules/unused-variable"}
+{"code":"F401","end_location":{"column":10,"row":1},"filename":"fib.py","fix":{"applicability":"sometimes","edits":[{"content":"","end_location":{"column":1,"row":2},"location":{"column":1,"row":1}}],"message":"Remove unused import: `os`"},"location":{"column":8,"row":1},"message":"`os` imported but unused","noqa_row":1,"url":"https://docs.astral.sh/ruff/rules/unused-import"}
+{"code":"F841","end_location":{"column":6,"row":6},"filename":"fib.py","fix":{"applicability":"sometimes","edits":[{"content":"","end_location":{"column":10,"row":6},"location":{"column":5,"row":6}}],"message":"Remove assignment to unused variable `x`"},"location":{"column":5,"row":6},"message":"Local variable `x` is assigned to but never used","noqa_row":6,"url":"https://docs.astral.sh/ruff/rules/unused-variable"}
 {"code":"F821","end_location":{"column":5,"row":1},"filename":"undef.py","fix":null,"location":{"column":4,"row":1},"message":"Undefined name `a`","noqa_row":1,"url":"https://docs.astral.sh/ruff/rules/undefined-name"}
 

crates/ruff_linter/src/rules/eradicate/rules/commented_out_code.rs

@@ -68,7 +68,7 @@ pub(crate) fn commented_out_code(
             let mut diagnostic = Diagnostic::new(CommentedOutCode, *range);
 
             if settings.rules.should_fix(Rule::CommentedOutCode) {
-                diagnostic.set_fix(Fix::manual(Edit::range_deletion(
+                diagnostic.set_fix(Fix::never_applies(Edit::range_deletion(
                     locator.full_lines_range(*range),
                 )));
             }

crates/ruff_linter/src/rules/flake8_annotations/rules/definition.rs

@@ -703,7 +703,7 @@ pub(crate) fn definition(
                         function.identifier(),
                     );
                     if checker.patch(diagnostic.kind.rule()) {
-                        diagnostic.set_fix(Fix::suggested(Edit::insertion(
+                        diagnostic.set_fix(Fix::sometimes_applies(Edit::insertion(
                             " -> None".to_string(),
                             function.parameters.range().end(),
                         )));
@@ -721,7 +721,7 @@ pub(crate) fn definition(
                 );
                 if checker.patch(diagnostic.kind.rule()) {
                     if let Some(return_type) = simple_magic_return_type(name) {
-                        diagnostic.set_fix(Fix::suggested(Edit::insertion(
+                        diagnostic.set_fix(Fix::sometimes_applies(Edit::insertion(
                             format!(" -> {return_type}"),
                             function.parameters.range().end(),
                         )));

crates/ruff_linter/src/rules/flake8_bugbear/rules/assert_false.rs

@@ -76,7 +76,7 @@ pub(crate) fn assert_false(checker: &mut Checker, stmt: &Stmt, test: &Expr, msg:
 
     let mut diagnostic = Diagnostic::new(AssertFalse, test.range());
     if checker.patch(diagnostic.kind.rule()) {
-        diagnostic.set_fix(Fix::suggested(Edit::range_replacement(
+        diagnostic.set_fix(Fix::sometimes_applies(Edit::range_replacement(
             checker.generator().stmt(&assertion_error(msg)),
             stmt.range(),
         )));

crates/ruff_linter/src/rules/flake8_bugbear/rules/duplicate_exceptions.rs

@@ -147,7 +147,7 @@ fn duplicate_handler_exceptions<'a>(
                 expr.range(),
             );
             if checker.patch(diagnostic.kind.rule()) {
-                diagnostic.set_fix(Fix::automatic(Edit::range_replacement(
+                diagnostic.set_fix(Fix::always_applies(Edit::range_replacement(
                     // Single exceptions don't require parentheses, but since we're _removing_
                     // parentheses, insert whitespace as needed.
                     if let [elt] = unique_elts.as_slice() {

crates/ruff_linter/src/rules/flake8_bugbear/rules/getattr_with_constant.rs

@@ -86,7 +86,7 @@ pub(crate) fn getattr_with_constant(
 
     let mut diagnostic = Diagnostic::new(GetAttrWithConstant, expr.range());
     if checker.patch(diagnostic.kind.rule()) {
-        diagnostic.set_fix(Fix::suggested(Edit::range_replacement(
+        diagnostic.set_fix(Fix::sometimes_applies(Edit::range_replacement(
             pad(
                 if matches!(
                     obj,

crates/ruff_linter/src/rules/flake8_bugbear/rules/mutable_argument_default.rs

@@ -200,5 +200,8 @@ fn move_initialization(
     }
 
     let initialization_edit = Edit::insertion(content, pos);
-    Some(Fix::manual_edits(default_edit, [initialization_edit]))
+    Some(Fix::never_applies_edits(
+        default_edit,
+        [initialization_edit],
+    ))
 }

crates/ruff_linter/src/rules/flake8_bugbear/rules/redundant_tuple_in_exception_handler.rs

@@ -85,7 +85,7 @@ pub(crate) fn redundant_tuple_in_exception_handler(
             // ```
             // Otherwise, the output will be invalid syntax, since we're removing a set of
             // parentheses.
-            diagnostic.set_fix(Fix::automatic(Edit::range_replacement(
+            diagnostic.set_fix(Fix::always_applies(Edit::range_replacement(
                 pad(
                     checker.generator().expr(elt),
                     type_.range(),

crates/ruff_linter/src/rules/flake8_bugbear/rules/setattr_with_constant.rs

@@ -109,7 +109,7 @@ pub(crate) fn setattr_with_constant(
         if expr == child.as_ref() {
             let mut diagnostic = Diagnostic::new(SetAttrWithConstant, expr.range());
             if checker.patch(diagnostic.kind.rule()) {
-                diagnostic.set_fix(Fix::suggested(Edit::range_replacement(
+                diagnostic.set_fix(Fix::sometimes_applies(Edit::range_replacement(
                     assignment(obj, name, value, checker.generator()),
                     expr.range(),
                 )));

crates/ruff_linter/src/rules/flake8_bugbear/rules/unreliable_callable_check.rs

@@ -83,7 +83,7 @@ pub(crate) fn unreliable_callable_check(
     if checker.patch(diagnostic.kind.rule()) {
         if id == "hasattr" {
             if checker.semantic().is_builtin("callable") {
-                diagnostic.set_fix(Fix::automatic(Edit::range_replacement(
+                diagnostic.set_fix(Fix::always_applies(Edit::range_replacement(
                     format!("callable({})", checker.locator().slice(obj)),
                     expr.range(),
                 )));

crates/ruff_linter/src/rules/flake8_bugbear/rules/unused_loop_control_variable.rs

@@ -168,7 +168,7 @@ pub(crate) fn unused_loop_control_variable(checker: &mut Checker, stmt_for: &ast
                         .filter(|binding| binding.start() >= expr.start())
                         .all(|binding| !binding.is_used())
                     {
-                        diagnostic.set_fix(Fix::suggested(Edit::range_replacement(
+                        diagnostic.set_fix(Fix::sometimes_applies(Edit::range_replacement(
                             rename,
                             expr.range(),
                         )));