Avoid flagging bare exception issues when exception is re-raised (#1124)

README.md

@@ -631,7 +631,7 @@ For more, see [flake8-blind-except](https://pypi.org/project/flake8-blind-except
 
 | Code | Name | Message | Fix |
 | ---- | ---- | ------- | --- |
-| BLE001 | BlindExcept | Blind except Exception: statement |  |
+| BLE001 | BlindExcept | Do not catch blind exception: `Exception` |  |
 
 ### flake8-boolean-trap (FBT)
 

resources/test/fixtures/flake8_blind_except/BLE.py

@@ -53,3 +53,11 @@ try:
         raise e
 except Exception:
     pass
+
+
+try:
+    pass
+except Exception as e:
+    raise bad
+except BaseException:
+    pass

src/check_ast.rs

@@ -1077,9 +1077,6 @@ where
                 if self.settings.enabled.contains(&CheckCode::B013) {
                     flake8_bugbear::plugins::redundant_tuple_in_exception_handler(self, handlers);
                 }
-                if self.settings.enabled.contains(&CheckCode::BLE001) {
-                    flake8_blind_except::plugins::blind_except(self, handlers);
-                }
             }
             StmtKind::Assign { targets, value, .. } => {
                 if self.settings.enabled.contains(&CheckCode::E731) {
@@ -2347,16 +2344,25 @@ where
             ExcepthandlerKind::ExceptHandler {
                 type_, name, body, ..
             } => {
-                if self.settings.enabled.contains(&CheckCode::E722) && type_.is_none() {
-                    self.add_check(Check::new(
-                        CheckKind::DoNotUseBareExcept,
+                if self.settings.enabled.contains(&CheckCode::E722) {
+                    if let Some(check) = pycodestyle::checks::do_not_use_bare_except(
+                        type_.as_deref(),
+                        body,
                         Range::from_located(excepthandler),
-                    ));
+                    ) {
+                        self.add_check(check);
+                    }
                 }
                 if self.settings.enabled.contains(&CheckCode::B904) {
-                    {
-                        flake8_bugbear::plugins::raise_without_from_inside_except(self, body);
-                    }
+                    flake8_bugbear::plugins::raise_without_from_inside_except(self, body);
+                }
+                if self.settings.enabled.contains(&CheckCode::BLE001) {
+                    flake8_blind_except::plugins::blind_except(
+                        self,
+                        type_.as_deref(),
+                        name.as_ref().map(String::as_str),
+                        body,
+                    );
                 }
                 match name {
                     Some(name) => {

src/checks.rs

@@ -631,7 +631,7 @@ pub enum CheckKind {
     BuiltinArgumentShadowing(String),
     BuiltinAttributeShadowing(String),
     // flake8-blind-except
-    BlindExcept,
+    BlindExcept(String),
     // flake8-bugbear
     AbstractBaseClassWithoutAbstractMethod(String),
     AssignmentToOsEnviron,
@@ -1045,7 +1045,7 @@ impl CheckCode {
             CheckCode::YTT302 => CheckKind::SysVersionCmpStr10,
             CheckCode::YTT303 => CheckKind::SysVersionSlice1Referenced,
             // flake8-blind-except
-            CheckCode::BLE001 => CheckKind::BlindExcept,
+            CheckCode::BLE001 => CheckKind::BlindExcept("Exception".to_string()),
             // pyupgrade
             CheckCode::UP001 => CheckKind::UselessMetaclassType,
             CheckCode::UP003 => CheckKind::TypeOfPrimitive(Primitive::Str),
@@ -1529,7 +1529,7 @@ impl CheckKind {
             CheckKind::UselessContextlibSuppress => &CheckCode::B022,
             CheckKind::UselessExpression => &CheckCode::B018,
             // flake8-blind-except
-            CheckKind::BlindExcept => &CheckCode::BLE001,
+            CheckKind::BlindExcept(_) => &CheckCode::BLE001,
             // flake8-comprehensions
             CheckKind::UnnecessaryGeneratorList => &CheckCode::C400,
             CheckKind::UnnecessaryGeneratorSet => &CheckCode::C401,
@@ -2460,7 +2460,7 @@ impl CheckKind {
                 format!("Possible hardcoded password: `\"{string}\"`")
             }
             // flake8-blind-except
-            CheckKind::BlindExcept => "Blind except Exception: statement".to_string(),
+            CheckKind::BlindExcept(name) => format!("Do not catch blind exception: `{name}`"),
             // mccabe
             CheckKind::FunctionIsTooComplex(name, complexity) => {
                 format!("`{name}` is too complex ({complexity})")

src/flake8_blind_except/plugins.rs

@@ -1,21 +1,42 @@
-use rustpython_ast::{Excepthandler, ExcepthandlerKind, ExprKind};
+use rustpython_ast::{Expr, ExprKind, Stmt, StmtKind};
 
 use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
-pub fn blind_except(checker: &mut Checker, handlers: &[Excepthandler]) {
-    for handler in handlers {
-        let ExcepthandlerKind::ExceptHandler { type_: Some(type_), .. } = &handler.node else {
-            continue;
-        };
-        let ExprKind::Name { id, .. } = &type_.node else {
-            continue;
-        };
-        for exception in ["BaseException", "Exception"] {
-            if id == exception {
+/// BLE001
+pub fn blind_except(
+    checker: &mut Checker,
+    type_: Option<&Expr>,
+    name: Option<&str>,
+    body: &[Stmt],
+) {
+    let Some(type_) = type_ else {
+        return;
+    };
+    let ExprKind::Name { id, .. } = &type_.node else {
+        return;
+    };
+    for exception in ["BaseException", "Exception"] {
+        if id == exception && checker.is_builtin(exception) {
+            // If the exception is re-raised, don't flag an error.
+            if !body.iter().any(|stmt| {
+                if let StmtKind::Raise { exc, .. } = &stmt.node {
+                    if let Some(exc) = exc {
+                        if let ExprKind::Name { id, .. } = &exc.node {
+                            name.map_or(false, |name| name == id)
+                        } else {
+                            false
+                        }
+                    } else {
+                        true
+                    }
+                } else {
+                    false
+                }
+            }) {
                 checker.add_check(Check::new(
-                    CheckKind::BlindExcept,
+                    CheckKind::BlindExcept(id.to_string()),
                     Range::from_located(type_),
                 ));
             }

src/flake8_blind_except/snapshots/ruff__flake8_blind_except__tests__BLE001_BLE.py.snap

@@ -2,31 +2,8 @@
 source: src/flake8_blind_except/mod.rs
 expression: checks
 ---
-- kind: BlindExcept
-  location:
-    row: 5
-    column: 7
-  end_location:
-    row: 5
-    column: 16
-  fix: ~
-- kind: BlindExcept
-  location:
-    row: 13
-    column: 7
-  end_location:
-    row: 13
-    column: 20
-  fix: ~
-- kind: BlindExcept
-  location:
-    row: 23
-    column: 7
-  end_location:
-    row: 23
-    column: 16
-  fix: ~
-- kind: BlindExcept
+- kind:
+    BlindExcept: BaseException
   location:
     row: 25
     column: 7
@@ -34,7 +11,8 @@ expression: checks
     row: 25
     column: 20
   fix: ~
-- kind: BlindExcept
+- kind:
+    BlindExcept: Exception
   location:
     row: 31
     column: 7
@@ -42,15 +20,8 @@ expression: checks
     row: 31
     column: 16
   fix: ~
-- kind: BlindExcept
-  location:
-    row: 36
-    column: 11
-  end_location:
-    row: 36
-    column: 24
-  fix: ~
-- kind: BlindExcept
+- kind:
+    BlindExcept: Exception
   location:
     row: 42
     column: 7
@@ -58,7 +29,8 @@ expression: checks
     row: 42
     column: 16
   fix: ~
-- kind: BlindExcept
+- kind:
+    BlindExcept: BaseException
   location:
     row: 45
     column: 11
@@ -66,15 +38,8 @@ expression: checks
     row: 45
     column: 24
   fix: ~
-- kind: BlindExcept
-  location:
-    row: 52
-    column: 11
-  end_location:
-    row: 52
-    column: 24
-  fix: ~
-- kind: BlindExcept
+- kind:
+    BlindExcept: Exception
   location:
     row: 54
     column: 7
@@ -82,4 +47,22 @@ expression: checks
     row: 54
     column: 16
   fix: ~
+- kind:
+    BlindExcept: Exception
+  location:
+    row: 60
+    column: 7
+  end_location:
+    row: 60
+    column: 16
+  fix: ~
+- kind:
+    BlindExcept: BaseException
+  location:
+    row: 62
+    column: 7
+  end_location:
+    row: 62
+    column: 20
+  fix: ~
 

src/pycodestyle/checks.rs

@@ -1,11 +1,65 @@
 use itertools::izip;
-use rustpython_ast::Location;
+use rustpython_ast::{Location, Stmt, StmtKind};
 use rustpython_parser::ast::{Cmpop, Expr, ExprKind};
 
 use crate::ast::types::Range;
 use crate::checks::{Check, CheckKind};
 use crate::source_code_locator::SourceCodeLocator;
 
+/// E721
+pub fn type_comparison(ops: &[Cmpop], comparators: &[Expr], location: Range) -> Vec<Check> {
+    let mut checks: Vec<Check> = vec![];
+
+    for (op, right) in izip!(ops, comparators) {
+        if !matches!(op, Cmpop::Is | Cmpop::IsNot | Cmpop::Eq | Cmpop::NotEq) {
+            continue;
+        }
+        match &right.node {
+            ExprKind::Call { func, args, .. } => {
+                if let ExprKind::Name { id, .. } = &func.node {
+                    // Ex) type(False)
+                    if id == "type" {
+                        if let Some(arg) = args.first() {
+                            // Allow comparison for types which are not obvious.
+                            if !matches!(arg.node, ExprKind::Name { .. }) {
+                                checks.push(Check::new(CheckKind::TypeComparison, location));
+                            }
+                        }
+                    }
+                }
+            }
+            ExprKind::Attribute { value, .. } => {
+                if let ExprKind::Name { id, .. } = &value.node {
+                    // Ex) types.IntType
+                    if id == "types" {
+                        checks.push(Check::new(CheckKind::TypeComparison, location));
+                    }
+                }
+            }
+            _ => {}
+        }
+    }
+
+    checks
+}
+
+/// E722
+pub fn do_not_use_bare_except(
+    type_: Option<&Expr>,
+    body: &[Stmt],
+    location: Range,
+) -> Option<Check> {
+    if type_.is_none()
+        && !body
+            .iter()
+            .any(|stmt| matches!(stmt.node, StmtKind::Raise { exc: None, .. }))
+    {
+        Some(Check::new(CheckKind::DoNotUseBareExcept, location))
+    } else {
+        None
+    }
+}
+
 fn is_ambiguous_name(name: &str) -> bool {
     name == "l" || name == "I" || name == "O"
 }
@@ -46,43 +100,6 @@ pub fn ambiguous_function_name(name: &str, location: Range) -> Option<Check> {
     }
 }
 
-/// E721
-pub fn type_comparison(ops: &[Cmpop], comparators: &[Expr], location: Range) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    for (op, right) in izip!(ops, comparators) {
-        if !matches!(op, Cmpop::Is | Cmpop::IsNot | Cmpop::Eq | Cmpop::NotEq) {
-            continue;
-        }
-        match &right.node {
-            ExprKind::Call { func, args, .. } => {
-                if let ExprKind::Name { id, .. } = &func.node {
-                    // Ex) type(False)
-                    if id == "type" {
-                        if let Some(arg) = args.first() {
-                            // Allow comparison for types which are not obvious.
-                            if !matches!(arg.node, ExprKind::Name { .. }) {
-                                checks.push(Check::new(CheckKind::TypeComparison, location));
-                            }
-                        }
-                    }
-                }
-            }
-            ExprKind::Attribute { value, .. } => {
-                if let ExprKind::Name { id, .. } = &value.node {
-                    // Ex) types.IntType
-                    if id == "types" {
-                        checks.push(Check::new(CheckKind::TypeComparison, location));
-                    }
-                }
-            }
-            _ => {}
-        }
-    }
-
-    checks
-}
-
 // See: https://docs.python.org/3/reference/lexical_analysis.html#string-and-bytes-literals
 const VALID_ESCAPE_SEQUENCES: &[char; 23] = &[
     '\n', '\\', '\'', '"', 'a', 'b', 'f', 'n', 'r', 't', 'v', '0', '1', '2', '3', '4', '5', '6',