[flake8-return] Recognize functions returning Never as non-return…

…ing (`RET503`)

crates/ruff_linter/resources/test/fixtures/flake8_return/RET503.py

@@ -331,17 +331,19 @@ def end_of_file():
 
 
 # function return type annotation NoReturn
+def bar() -> NoReturn:
+    abort()
+
 def foo(x: int) -> int:
-    def bar() -> NoReturn:
-        abort()
     if x == 5:
         return 5
     bar()
 
 
+def raises(value: str) -> NoReturn:
+    raise RuntimeError("something went wrong")
+
 def foo(string: str) -> str:
-    def raises(value: str) -> NoReturn:
-        raise RuntimeError("something went wrong")
 
     match string:
         case "a":
@@ -353,17 +355,52 @@ def raises(value: str) -> NoReturn:
         case _:
             raises(string)
 
+def bar() -> NoReturn:
+    a = 1 + 2
+    raise AssertionError("Very bad")
 
 def foo() -> int:
     def baz() -> int:
         return 1
 
+    if baz() > 3:
+        return 1
+    bar()
+
+
 
-    def bar() -> NoReturn:
-        a = 1 + 2
-        raise AssertionError("Very bad")
+# function return type annotation typing_extensions.Never
+def bar() -> typing_extensions.Never:
+    abort()
+
+def foo(x: int) -> int:
+    if x == 5:
+        return 5
+    bar()
 
 
+def raises(value: str) -> typing_extensions.Never:
+    raise RuntimeError("something went wrong")
+
+def foo(string: str) -> str:
+
+    match string:
+        case "a":
+            return "first"
+        case "b":
+            return "second"
+        case "c":
+            return "third"
+        case _:
+            raises(string)
+
+def bar() -> typing_extensions.Never:
+    a = 1 + 2
+    raise AssertionError("Very bad")
+
+def foo() -> int:
+    def baz() -> int:
+        return 1
 
     if baz() > 3:
         return 1

crates/ruff_linter/resources/test/fixtures/flake8_return/RET503_nested_functions.py

@@ -0,0 +1,86 @@
+from posix import abort
+from typing import NoReturn
+
+import typing_extensions
+
+
+
+# function return type annotation NoReturn
+def foo(x: int) -> int:
+    def bar() -> NoReturn:
+        abort()
+    if x == 5:
+        return 5
+    bar()
+
+
+def foo(string: str) -> str:
+    def raises(value: str) -> NoReturn:
+        raise RuntimeError("something went wrong")
+
+    match string:
+        case "a":
+            return "first"
+        case "b":
+            return "second"
+        case "c":
+            return "third"
+        case _:
+            raises(string)
+
+
+def foo() -> int:
+    def baz() -> int:
+        return 1
+
+
+    def bar() -> NoReturn:
+        a = 1 + 2
+        raise AssertionError("Very bad")
+
+
+
+    if baz() > 3:
+        return 1
+    bar()
+
+
+
+# function return type annotation typing_extensions.Never
+def foo(x: int) -> int:
+    def bar() -> typing_extensions.Never:
+        abort()
+    if x == 5:
+        return 5
+    bar()
+
+
+def foo(string: str) -> str:
+    def raises(value: str) -> typing_extensions.Never:
+        raise RuntimeError("something went wrong")
+
+    match string:
+        case "a":
+            return "first"
+        case "b":
+            return "second"
+        case "c":
+            return "third"
+        case _:
+            raises(string)
+
+
+def foo() -> int:
+    def baz() -> int:
+        return 1
+
+
+    def bar() -> typing_extensions.Never:
+        a = 1 + 2
+        raise AssertionError("Very bad")
+
+
+
+    if baz() > 3:
+        return 1
+    bar()

crates/ruff_linter/src/rules/flake8_return/mod.rs

@@ -52,4 +52,15 @@ mod tests {
         assert_messages!(snapshot, diagnostics);
         Ok(())
     }
+
+    #[test]
+    #[ignore = "Non-returning nested functions are not handled correctly"]
+    fn noreturn_nested_functions() -> Result<()> {
+        let diagnostics = test_path(
+            Path::new("flake8_return/RET503_nested_functions.py"),
+            &LinterSettings::for_rule(Rule::ImplicitReturn),
+        )?;
+        assert!(diagnostics.is_empty());
+        Ok(())
+    }
 }

crates/ruff_linter/src/rules/flake8_return/rules/function.rs

@@ -450,6 +450,7 @@ fn is_noreturn_func(func: &Expr, semantic: &SemanticModel) -> bool {
     };
 
     semantic.match_typing_qualified_name(&qualified_name, "NoReturn")
+        || semantic.match_typing_qualified_name(&qualified_name, "Never")
 }
 
 fn add_return_none(checker: &mut Checker, stmt: &Stmt, range: TextRange) {

crates/ruff_linter/src/rules/flake8_return/snapshots/ruff_linter__rules__flake8_return__tests__RET503_RET503.py.snap

@@ -403,71 +403,17 @@ RET503.py:329:5: RET503 [*] Missing explicit `return` at the end of function abl
 332 333 | 
 333 334 | # function return type annotation NoReturn
 
-RET503.py:339:5: RET503 [*] Missing explicit `return` at the end of function able to return non-`None` value
+RET503.py:415:13: RET503 [*] Missing explicit `return` at the end of function able to return non-`None` value
     |
-337 |     if x == 5:
-338 |         return 5
-339 |     bar()
-    |     ^^^^^ RET503
-    |
-    = help: Add explicit `return` statement
-
-ℹ Unsafe fix
-337 337 |     if x == 5:
-338 338 |         return 5
-339 339 |     bar()
-    340 |+    return None
-340 341 | 
-341 342 | 
-342 343 | def foo(string: str) -> str:
-
-RET503.py:354:13: RET503 [*] Missing explicit `return` at the end of function able to return non-`None` value
-    |
-352 |             return "third"
-353 |         case _:
-354 |             raises(string)
-    |             ^^^^^^^^^^^^^^ RET503
-    |
-    = help: Add explicit `return` statement
-
-ℹ Unsafe fix
-352 352 |             return "third"
-353 353 |         case _:
-354 354 |             raises(string)
-    355 |+            return None
-355 356 | 
-356 357 | 
-357 358 | def foo() -> int:
-
-RET503.py:370:5: RET503 [*] Missing explicit `return` at the end of function able to return non-`None` value
-    |
-368 |     if baz() > 3:
-369 |         return 1
-370 |     bar()
-    |     ^^^^^ RET503
-    |
-    = help: Add explicit `return` statement
-
-ℹ Unsafe fix
-368 368 |     if baz() > 3:
-369 369 |         return 1
-370 370 |     bar()
-    371 |+    return None
-371 372 | 
-372 373 | 
-373 374 | def f():
-
-RET503.py:378:13: RET503 [*] Missing explicit `return` at the end of function able to return non-`None` value
-    |
-376 |     else:
-377 |         with c:
-378 |             d
+413 |     else:
+414 |         with c:
+415 |             d
     |             ^ RET503
     |
     = help: Add explicit `return` statement
 
 ℹ Unsafe fix
-376 376 |     else:
-377 377 |         with c:
-378 378 |             d
-    379 |+            return None
+413 413 |     else:
+414 414 |         with c:
+415 415 |             d
+    416 |+            return None

crates/ruff_linter/src/rules/flake8_return/snapshots/ruff_linter__rules__flake8_return__tests__preview__RET503_RET503.py.snap

@@ -411,99 +411,20 @@ RET503.py:326:1: RET503 [*] Missing explicit `return` at the end of function abl
 332 333 | 
 333 334 | # function return type annotation NoReturn
 
-RET503.py:334:1: RET503 [*] Missing explicit `return` at the end of function able to return non-`None` value
-    |
-333 |   # function return type annotation NoReturn
-334 | / def foo(x: int) -> int:
-335 | |     def bar() -> NoReturn:
-336 | |         abort()
-337 | |     if x == 5:
-338 | |         return 5
-339 | |     bar()
-    | |_________^ RET503
-    |
-    = help: Add explicit `return` statement
-
-ℹ Unsafe fix
-337 337 |     if x == 5:
-338 338 |         return 5
-339 339 |     bar()
-    340 |+    return None
-340 341 | 
-341 342 | 
-342 343 | def foo(string: str) -> str:
-
-RET503.py:342:1: RET503 [*] Missing explicit `return` at the end of function able to return non-`None` value
-    |
-342 | / def foo(string: str) -> str:
-343 | |     def raises(value: str) -> NoReturn:
-344 | |         raise RuntimeError("something went wrong")
-345 | | 
-346 | |     match string:
-347 | |         case "a":
-348 | |             return "first"
-349 | |         case "b":
-350 | |             return "second"
-351 | |         case "c":
-352 | |             return "third"
-353 | |         case _:
-354 | |             raises(string)
-    | |__________________________^ RET503
-    |
-    = help: Add explicit `return` statement
-
-ℹ Unsafe fix
-352 352 |             return "third"
-353 353 |         case _:
-354 354 |             raises(string)
-    355 |+    return None
-355 356 | 
-356 357 | 
-357 358 | def foo() -> int:
-
-RET503.py:357:1: RET503 [*] Missing explicit `return` at the end of function able to return non-`None` value
-    |
-357 | / def foo() -> int:
-358 | |     def baz() -> int:
-359 | |         return 1
-360 | | 
-361 | | 
-362 | |     def bar() -> NoReturn:
-363 | |         a = 1 + 2
-364 | |         raise AssertionError("Very bad")
-365 | | 
-366 | | 
-367 | | 
-368 | |     if baz() > 3:
-369 | |         return 1
-370 | |     bar()
-    | |_________^ RET503
-    |
-    = help: Add explicit `return` statement
-
-ℹ Unsafe fix
-368 368 |     if baz() > 3:
-369 369 |         return 1
-370 370 |     bar()
-    371 |+    return None
-371 372 | 
-372 373 | 
-373 374 | def f():
-
-RET503.py:373:1: RET503 [*] Missing explicit `return` at the end of function able to return non-`None` value
-    |
-373 | / def f():
-374 | |     if a:
-375 | |         return b
-376 | |     else:
-377 | |         with c:
-378 | |             d
+RET503.py:410:1: RET503 [*] Missing explicit `return` at the end of function able to return non-`None` value
+    |
+410 | / def f():
+411 | |     if a:
+412 | |         return b
+413 | |     else:
+414 | |         with c:
+415 | |             d
     | |_____________^ RET503
     |
     = help: Add explicit `return` statement
 
 ℹ Unsafe fix
-376 376 |     else:
-377 377 |         with c:
-378 378 |             d
-    379 |+    return None
+413 413 |     else:
+414 414 |         with c:
+415 415 |             d
+    416 |+    return None