diff --git a/crates/red_knot_python_semantic/resources/mdtest/boolean/short_circuit.md b/crates/red_knot_python_semantic/resources/mdtest/boolean/short_circuit.md new file mode 100644 index 0000000000..ed6fa58fbc --- /dev/null +++ b/crates/red_knot_python_semantic/resources/mdtest/boolean/short_circuit.md @@ -0,0 +1,78 @@ +# Short-Circuit Evaluation + +## Not all boolean expressions must be evaluated + +In `or` expressions, if the left-hand side is truthy, the right-hand side is not evaluated. +Similarly, in `and` expressions, if the left-hand side is falsy, the right-hand side is not +evaluated. + +```py +def bool_instance() -> bool: + return True + +if bool_instance() or (x := 1): + # error: [possibly-unresolved-reference] + reveal_type(x) # revealed: Unbound | Literal[1] + +if bool_instance() and (x := 1): + # error: [possibly-unresolved-reference] + reveal_type(x) # revealed: Unbound | Literal[1] +``` + +## First expression is always evaluated + +```py +def bool_instance() -> bool: + return True + +if (x := 1) or bool_instance(): + reveal_type(x) # revealed: Literal[1] + +if (x := 1) and bool_instance(): + reveal_type(x) # revealed: Literal[1] +``` + +## Statically known truthiness + +```py +if True or (x := 1): + # TODO: infer that the second arm is never executed so type should be just "Unbound". + # error: [possibly-unresolved-reference] + reveal_type(x) # revealed: Unbound | Literal[1] + +if True and (x := 1): + # TODO: infer that the second arm is always executed so type should be just "Literal[1]". + # error: [possibly-unresolved-reference] + reveal_type(x) # revealed: Unbound | Literal[1] +``` + +## Later expressions can always use variables from earlier expressions + +```py +def bool_instance() -> bool: + return True + +bool_instance() or (x := 1) or reveal_type(x) # revealed: Literal[1] + +# error: [unresolved-reference] +bool_instance() or reveal_type(y) or (y := 1) # revealed: Unbound +``` + +## Nested expressions + +```py +def bool_instance() -> bool: + return True + +if bool_instance() or ((x := 1) and bool_instance()): + # error: "Name `x` used when possibly not defined" + reveal_type(x) # revealed: Unbound | Literal[1] + +if ((y := 1) and bool_instance()) or bool_instance(): + reveal_type(y) # revealed: Literal[1] + +# error: [possibly-unresolved-reference] +if (bool_instance() and (z := 1)) or reveal_type(z): # revealed: Unbound | Literal[1] + # error: [possibly-unresolved-reference] + reveal_type(z) # revealed: Unbound | Literal[1] +``` diff --git a/crates/red_knot_python_semantic/src/semantic_index/builder.rs b/crates/red_knot_python_semantic/src/semantic_index/builder.rs index 523682fcd3..e715cdd0df 100644 --- a/crates/red_knot_python_semantic/src/semantic_index/builder.rs +++ b/crates/red_knot_python_semantic/src/semantic_index/builder.rs @@ -1106,6 +1106,27 @@ where }, ); } + ast::Expr::BoolOp(ast::ExprBoolOp { + values, + range: _, + op: _, + }) => { + // TODO detect statically known truthy or falsy values (via type inference, not naive + // AST inspection, so we can't simplify here, need to record test expression for + // later checking) + let mut snapshots = vec![]; + + for (index, value) in values.iter().enumerate() { + // The first item of BoolOp is always evaluated + if index > 0 { + snapshots.push(self.flow_snapshot()); + } + self.visit_expr(value); + } + for snapshot in snapshots { + self.flow_merge(snapshot); + } + } _ => { walk_expr(self, expr); } diff --git a/crates/red_knot_test/src/parser.rs b/crates/red_knot_test/src/parser.rs index 8b1445020d..79e9306a5c 100644 --- a/crates/red_knot_test/src/parser.rs +++ b/crates/red_knot_test/src/parser.rs @@ -148,7 +148,7 @@ static HEADER_RE: LazyLock = /// Matches a code block fenced by triple backticks, possibly with language and `key=val` /// configuration items following the opening backticks (in the "tag string" of the code block). static CODE_RE: LazyLock = LazyLock::new(|| { - Regex::new(r"^```(?(?-u:\w)+)?(?(?: +\S+)*)\s*\n(?(?:.|\n)*?)\n?```\s*\n") + Regex::new(r"^```(?(?-u:\w)+)?(?(?: +\S+)*)\s*\n(?(?:.|\n)*?)\n?```\s*\n?") .unwrap() }); @@ -421,6 +421,31 @@ mod tests { assert_eq!(file.code, "x = 1"); } + #[test] + fn no_new_line_at_eof() { + let source = dedent( + " + ```py + x = 1 + ```", + ); + let mf = super::parse("file.md", &source).unwrap(); + + let [test] = &mf.tests().collect::>()[..] else { + panic!("expected one test"); + }; + + assert_eq!(test.name(), "file.md"); + + let [file] = test.files().collect::>()[..] else { + panic!("expected one file"); + }; + + assert_eq!(file.path, "test.py"); + assert_eq!(file.lang, "py"); + assert_eq!(file.code, "x = 1"); + } + #[test] fn multiple_tests() { let source = dedent(