From 099d5414f29040f527257fa4db01c51a26cffe56 Mon Sep 17 00:00:00 2001
From: Charlie Marsh <charlie.r.marsh@gmail.com>
Date: Sun, 12 Feb 2023 11:48:13 -0500
Subject: [PATCH] Allow non-verbose raise when cause is present (#2816)

The motivating issue here is of the following form:

```py
try:
    raise Exception("We want to hide this error message")
except Exception:
    try:
        raise Exception("We want to show this")
    except Exception as exc:
        raise exc from None
```

However, I think we should avoid this if _any_ cause is present, since causes require a named exception.

Closes #2814.
---
 .../test/fixtures/tryceratops/TRY201.py       | 10 ++++++++
 .../rules/tryceratops/rules/verbose_raise.rs  | 23 +++++++++++--------
 ...atops__tests__verbose-raise_TRY201.py.snap | 10 ++++----
 3 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/crates/ruff/resources/test/fixtures/tryceratops/TRY201.py b/crates/ruff/resources/test/fixtures/tryceratops/TRY201.py
index 9ed57caf82..1ed7aa9e0b 100644
--- a/crates/ruff/resources/test/fixtures/tryceratops/TRY201.py
+++ b/crates/ruff/resources/test/fixtures/tryceratops/TRY201.py
@@ -27,6 +27,7 @@ def good():
         logger.exception("process failed")
         raise
 
+
 def still_good():
     try:
         process()
@@ -35,6 +36,14 @@ def still_good():
         raise
 
 
+def still_good_too():
+    try:
+        process()
+    except MyException as e:
+        print(e)
+        raise e from None
+
+
 def still_actually_good():
     try:
         process()
@@ -60,5 +69,6 @@ def bad_that_needs_recursion_2():
     except MyException as e:
         logger.exception("process failed")
         if True:
+
             def foo():
                 raise e
diff --git a/crates/ruff/src/rules/tryceratops/rules/verbose_raise.rs b/crates/ruff/src/rules/tryceratops/rules/verbose_raise.rs
index 2119236a2e..4fa92d9618 100644
--- a/crates/ruff/src/rules/tryceratops/rules/verbose_raise.rs
+++ b/crates/ruff/src/rules/tryceratops/rules/verbose_raise.rs
@@ -20,7 +20,7 @@ impl Violation for VerboseRaise {
 
 #[derive(Default)]
 struct RaiseStatementVisitor<'a> {
-    raises: Vec<Option<&'a Expr>>,
+    raises: Vec<(Option<&'a Expr>, Option<&'a Expr>)>,
 }
 
 impl<'a, 'b> Visitor<'b> for RaiseStatementVisitor<'a>
@@ -29,7 +29,7 @@ where
 {
     fn visit_stmt(&mut self, stmt: &'b Stmt) {
         match &stmt.node {
-            StmtKind::Raise { exc, .. } => self.raises.push(exc.as_ref().map(|expr| &**expr)),
+            StmtKind::Raise { exc, cause } => self.raises.push((exc.as_deref(), cause.as_deref())),
             StmtKind::Try {
                 body, finalbody, ..
             } => {
@@ -59,13 +59,18 @@ pub fn verbose_raise(checker: &mut Checker, handlers: &[Excepthandler]) {
                 }
                 visitor.raises
             };
-            for expr in raises.into_iter().flatten() {
-                // ...and the raised object is bound to the same name...
-                if let ExprKind::Name { id, .. } = &expr.node {
-                    if id == exception_name {
-                        checker
-                            .diagnostics
-                            .push(Diagnostic::new(VerboseRaise, Range::from_located(expr)));
+            for (exc, cause) in raises {
+                if cause.is_some() {
+                    continue;
+                }
+                if let Some(exc) = exc {
+                    // ...and the raised object is bound to the same name...
+                    if let ExprKind::Name { id, .. } = &exc.node {
+                        if id == exception_name {
+                            checker
+                                .diagnostics
+                                .push(Diagnostic::new(VerboseRaise, Range::from_located(exc)));
+                        }
                     }
                 }
             }
diff --git a/crates/ruff/src/rules/tryceratops/snapshots/ruff__rules__tryceratops__tests__verbose-raise_TRY201.py.snap b/crates/ruff/src/rules/tryceratops/snapshots/ruff__rules__tryceratops__tests__verbose-raise_TRY201.py.snap
index e6c03c5f6c..f230c296b6 100644
--- a/crates/ruff/src/rules/tryceratops/snapshots/ruff__rules__tryceratops__tests__verbose-raise_TRY201.py.snap
+++ b/crates/ruff/src/rules/tryceratops/snapshots/ruff__rules__tryceratops__tests__verbose-raise_TRY201.py.snap
@@ -1,5 +1,5 @@
 ---
-source: src/rules/tryceratops/mod.rs
+source: crates/ruff/src/rules/tryceratops/mod.rs
 expression: diagnostics
 ---
 - kind:
@@ -15,20 +15,20 @@ expression: diagnostics
 - kind:
     VerboseRaise: ~
   location:
-    row: 54
+    row: 63
     column: 18
   end_location:
-    row: 54
+    row: 63
     column: 19
   fix: ~
   parent: ~
 - kind:
     VerboseRaise: ~
   location:
-    row: 64
+    row: 74
     column: 22
   end_location:
-    row: 64
+    row: 74
     column: 23
   fix: ~
   parent: ~