Implement W0602 (global-variable-not-assigned) (#1179)

resources/test/fixtures/pylint/global_variable_not_assigned.py

@@ -0,0 +1,32 @@
+###
+# Errors.
+###
+def f():
+    global x
+
+
+def f():
+    global x
+
+    print(x)
+
+
+###
+# Non-errors.
+###
+def f():
+    global x
+
+    x = 1
+
+
+def f():
+    global x
+
+    (x, y) = (1, 2)
+
+
+def f():
+    global x
+
+    del x

src/check_ast.rs

@@ -3174,6 +3174,7 @@ impl<'a> Checker<'a> {
             && !self.settings.enabled.contains(&CheckCode::F405)
             && !self.settings.enabled.contains(&CheckCode::F811)
             && !self.settings.enabled.contains(&CheckCode::F822)
+            && !self.settings.enabled.contains(&CheckCode::PLW0602)
         {
             return;
         }
@@ -3185,6 +3186,19 @@ impl<'a> Checker<'a> {
             .rev()
             .map(|index| &self.scopes[*index])
         {
+            // PLW0602
+            if self.settings.enabled.contains(&CheckCode::PLW0602) {
+                for (name, index) in &scope.values {
+                    let binding = &self.bindings[*index];
+                    if matches!(binding.kind, BindingKind::Global) {
+                        checks.push(Check::new(
+                            CheckKind::GlobalVariableNotAssigned((*name).to_string()),
+                            binding.range,
+                        ));
+                    }
+                }
+            }
+
             // Imports in classes are public members.
             if matches!(scope.kind, ScopeKind::Class(..)) {
                 continue;

src/checks.rs

@@ -106,6 +106,7 @@ pub enum CheckCode {
     PLR1701,
     PLR1722,
     PLW0120,
+    PLW0602,
     // flake8-builtins
     A001,
     A002,
@@ -639,6 +640,7 @@ pub enum CheckKind {
     AwaitOutsideAsync,
     ConsiderMergingIsinstance(String, Vec<String>),
     ConsiderUsingFromImport(String, String),
+    GlobalVariableNotAssigned(String),
     MisplacedComparisonConstant(String),
     PropertyWithParameters,
     UnnecessaryDirectLambdaCall,
@@ -963,6 +965,7 @@ impl CheckCode {
             }
             CheckCode::PLR1722 => CheckKind::UseSysExit("exit".to_string()),
             CheckCode::PLW0120 => CheckKind::UselessElseOnLoop,
+            CheckCode::PLW0602 => CheckKind::GlobalVariableNotAssigned("...".to_string()),
             // flake8-builtins
             CheckCode::A001 => CheckKind::BuiltinVariableShadowing("...".to_string()),
             CheckCode::A002 => CheckKind::BuiltinArgumentShadowing("...".to_string()),
@@ -1412,6 +1415,7 @@ impl CheckCode {
             CheckCode::PLR1701 => CheckCategory::Pylint,
             CheckCode::PLR1722 => CheckCategory::Pylint,
             CheckCode::PLW0120 => CheckCategory::Pylint,
+            CheckCode::PLW0602 => CheckCategory::Pylint,
             CheckCode::Q000 => CheckCategory::Flake8Quotes,
             CheckCode::Q001 => CheckCategory::Flake8Quotes,
             CheckCode::Q002 => CheckCategory::Flake8Quotes,
@@ -1537,11 +1541,12 @@ impl CheckKind {
             CheckKind::AwaitOutsideAsync => &CheckCode::PLE1142,
             CheckKind::ConsiderMergingIsinstance(..) => &CheckCode::PLR1701,
             CheckKind::ConsiderUsingFromImport(..) => &CheckCode::PLR0402,
+            CheckKind::GlobalVariableNotAssigned(..) => &CheckCode::PLW0602,
             CheckKind::MisplacedComparisonConstant(..) => &CheckCode::PLC2201,
-            CheckKind::UsedPriorGlobalDeclaration(..) => &CheckCode::PLE0118,
             CheckKind::PropertyWithParameters => &CheckCode::PLR0206,
             CheckKind::UnnecessaryDirectLambdaCall => &CheckCode::PLC3002,
             CheckKind::UseSysExit(_) => &CheckCode::PLR1722,
+            CheckKind::UsedPriorGlobalDeclaration(..) => &CheckCode::PLE0118,
             CheckKind::UselessElseOnLoop => &CheckCode::PLW0120,
             CheckKind::UselessImportAlias => &CheckCode::PLC0414,
             // flake8-builtins
@@ -1964,6 +1969,9 @@ impl CheckKind {
             CheckKind::UsedPriorGlobalDeclaration(name, line) => {
                 format!("Name `{name}` is used prior to global declaration on line {line}")
             }
+            CheckKind::GlobalVariableNotAssigned(name) => {
+                format!("Using global for `{name}` but no assignment is done")
+            }
             CheckKind::AwaitOutsideAsync => {
                 "`await` should be used within an async function".to_string()
             }

src/checks_gen.rs

@@ -342,6 +342,9 @@ pub enum CheckCodePrefix {
     PLW01,
     PLW012,
     PLW0120,
+    PLW06,
+    PLW060,
+    PLW0602,
     Q,
     Q0,
     Q00,
@@ -1375,11 +1378,14 @@ impl CheckCodePrefix {
             CheckCodePrefix::PLR1701 => vec![CheckCode::PLR1701],
             CheckCodePrefix::PLR172 => vec![CheckCode::PLR1722],
             CheckCodePrefix::PLR1722 => vec![CheckCode::PLR1722],
-            CheckCodePrefix::PLW => vec![CheckCode::PLW0120],
-            CheckCodePrefix::PLW0 => vec![CheckCode::PLW0120],
+            CheckCodePrefix::PLW => vec![CheckCode::PLW0120, CheckCode::PLW0602],
+            CheckCodePrefix::PLW0 => vec![CheckCode::PLW0120, CheckCode::PLW0602],
             CheckCodePrefix::PLW01 => vec![CheckCode::PLW0120],
             CheckCodePrefix::PLW012 => vec![CheckCode::PLW0120],
             CheckCodePrefix::PLW0120 => vec![CheckCode::PLW0120],
+            CheckCodePrefix::PLW06 => vec![CheckCode::PLW0602],
+            CheckCodePrefix::PLW060 => vec![CheckCode::PLW0602],
+            CheckCodePrefix::PLW0602 => vec![CheckCode::PLW0602],
             CheckCodePrefix::Q => vec![
                 CheckCode::Q000,
                 CheckCode::Q001,
@@ -2153,6 +2159,9 @@ impl CheckCodePrefix {
             CheckCodePrefix::PLW01 => SuffixLength::Two,
             CheckCodePrefix::PLW012 => SuffixLength::Three,
             CheckCodePrefix::PLW0120 => SuffixLength::Four,
+            CheckCodePrefix::PLW06 => SuffixLength::Two,
+            CheckCodePrefix::PLW060 => SuffixLength::Three,
+            CheckCodePrefix::PLW0602 => SuffixLength::Four,
             CheckCodePrefix::Q => SuffixLength::Zero,
             CheckCodePrefix::Q0 => SuffixLength::One,
             CheckCodePrefix::Q00 => SuffixLength::Two,

src/pylint/mod.rs

@@ -27,6 +27,7 @@ mod tests {
     #[test_case(CheckCode::PLR1722, Path::new("consider_using_sys_exit_5.py"); "PLR1722_5")]
     #[test_case(CheckCode::PLR1722, Path::new("consider_using_sys_exit_6.py"); "PLR1722_6")]
     #[test_case(CheckCode::PLW0120, Path::new("useless_else_on_loop.py"); "PLW0120")]
+    #[test_case(CheckCode::PLW0602, Path::new("global_variable_not_assigned.py"); "PLW0602")]
     fn checks(check_code: CheckCode, path: &Path) -> Result<()> {
         let snapshot = format!("{}_{}", check_code.as_ref(), path.to_string_lossy());
         let mut checks = test_path(

src/pylint/snapshots/ruff__pylint__tests__PLW0602_global_variable_not_assigned.py.snap

@@ -0,0 +1,23 @@
+---
+source: src/pylint/mod.rs
+expression: checks
+---
+- kind:
+    GlobalVariableNotAssigned: x
+  location:
+    row: 5
+    column: 4
+  end_location:
+    row: 5
+    column: 12
+  fix: ~
+- kind:
+    GlobalVariableNotAssigned: x
+  location:
+    row: 9
+    column: 4
+  end_location:
+    row: 9
+    column: 12
+  fix: ~
+