diff --git a/clippy_lints/src/methods/needless_option_take.rs b/clippy_lints/src/methods/needless_option_take.rs index 829c118d2916..c41ce2481d74 100644 --- a/clippy_lints/src/methods/needless_option_take.rs +++ b/clippy_lints/src/methods/needless_option_take.rs @@ -1,9 +1,6 @@ -use clippy_utils::diagnostics::span_lint_and_sugg; -use clippy_utils::match_def_path; -use clippy_utils::source::snippet_with_applicability; +use clippy_utils::diagnostics::span_lint_and_note; use clippy_utils::ty::is_type_diagnostic_item; -use rustc_errors::Applicability; -use rustc_hir::Expr; +use rustc_hir::{Expr, ExprKind, QPath}; use rustc_lint::LateContext; use rustc_span::sym; @@ -11,20 +8,17 @@ use super::NEEDLESS_OPTION_TAKE; pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, recv: &'tcx Expr<'_>) { // Checks if expression type is equal to sym::Option and if the expr is not a syntactic place - if !recv.is_syntactic_place_expr() && is_expr_option(cx, recv) && has_expr_as_ref_path(cx, recv) { - let mut applicability = Applicability::MachineApplicable; - span_lint_and_sugg( - cx, - NEEDLESS_OPTION_TAKE, - expr.span, - "called `Option::take()` on a temporary value", - "try", - format!( - "{}", - snippet_with_applicability(cx, recv.span, "..", &mut applicability) - ), - applicability, - ); + if !recv.is_syntactic_place_expr() && is_expr_option(cx, recv) { + if let Some(function_name) = source_of_temporary_value(recv) { + span_lint_and_note( + cx, + NEEDLESS_OPTION_TAKE, + expr.span, + "called `Option::take()` on a temporary value", + None, + format!("`{function_name}` creates a temporary value, so calling take() has no effect"), + ); + } } } @@ -33,9 +27,24 @@ fn is_expr_option(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool { is_type_diagnostic_item(cx, expr_type, sym::Option) } -fn has_expr_as_ref_path(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool { - if let Some(ref_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) { - return match_def_path(cx, ref_id, &["core", "option", "Option", "as_ref"]); +/// Returns the string of the function call that creates the temporary. +/// When this function is called, we are reasonably certain that the `ExprKind` is either +/// `Call` or `MethodCall` because we already checked that the expression is not +/// `is_syntactic_place_expr()`. +fn source_of_temporary_value<'a>(expr: &'a Expr<'_>) -> Option<&'a str> { + match expr.peel_borrows().kind { + ExprKind::Call(function, _) => { + if let ExprKind::Path(QPath::Resolved(_, func_path)) = function.kind { + if !func_path.segments.is_empty() { + return Some(func_path.segments[0].ident.name.as_str()); + } + } + if let ExprKind::Path(QPath::TypeRelative(_, func_path_segment)) = function.kind { + return Some(func_path_segment.ident.name.as_str()); + } + None + }, + ExprKind::MethodCall(path_segment, ..) => Some(path_segment.ident.name.as_str()), + _ => None, } - false } diff --git a/tests/ui/needless_option_take.fixed b/tests/ui/needless_option_take.fixed deleted file mode 100644 index d732a2686cb9..000000000000 --- a/tests/ui/needless_option_take.fixed +++ /dev/null @@ -1,13 +0,0 @@ -fn main() { - println!("Testing non erroneous option_take_on_temporary"); - let mut option = Some(1); - let _ = Box::new(move || option.take().unwrap()); - - println!("Testing non erroneous option_take_on_temporary"); - let x = Some(3); - x.as_ref(); - - println!("Testing erroneous option_take_on_temporary"); - let x = Some(3); - x.as_ref(); -} diff --git a/tests/ui/needless_option_take.rs b/tests/ui/needless_option_take.rs index f947d874e064..c6807718a758 100644 --- a/tests/ui/needless_option_take.rs +++ b/tests/ui/needless_option_take.rs @@ -1,3 +1,15 @@ +struct MyStruct; + +impl MyStruct { + pub fn get_option() -> Option { + todo!() + } +} + +fn return_option() -> Option { + todo!() +} + fn main() { println!("Testing non erroneous option_take_on_temporary"); let mut option = Some(1); @@ -7,7 +19,40 @@ fn main() { let x = Some(3); x.as_ref(); - println!("Testing erroneous option_take_on_temporary"); let x = Some(3); x.as_ref().take(); + //~^ ERROR: called `Option::take()` on a temporary value + + println!("Testing non erroneous option_take_on_temporary"); + let mut x = Some(3); + let y = x.as_mut(); + + let mut x = Some(3); + let y = x.as_mut().take(); + //~^ ERROR: called `Option::take()` on a temporary value + let y = x.replace(289).take(); + //~^ ERROR: called `Option::take()` on a temporary value + + let y = Some(3).as_mut().take(); + //~^ ERROR: called `Option::take()` on a temporary value + + let y = Option::as_mut(&mut x).take(); + //~^ ERROR: called `Option::take()` on a temporary value + + let x = return_option(); + let x = return_option().take(); + //~^ ERROR: called `Option::take()` on a temporary value + + let x = MyStruct::get_option(); + let x = MyStruct::get_option().take(); + //~^ ERROR: called `Option::take()` on a temporary value + + let mut my_vec = vec![1, 2, 3]; + my_vec.push(4); + let y = my_vec.first(); + let y = my_vec.first().take(); + //~^ ERROR: called `Option::take()` on a temporary value + + let y = my_vec.first().take(); + //~^ ERROR: called `Option::take()` on a temporary value } diff --git a/tests/ui/needless_option_take.stderr b/tests/ui/needless_option_take.stderr index 4a73ccb86d08..e036bd53170a 100644 --- a/tests/ui/needless_option_take.stderr +++ b/tests/ui/needless_option_take.stderr @@ -1,11 +1,76 @@ error: called `Option::take()` on a temporary value - --> tests/ui/needless_option_take.rs:12:5 + --> tests/ui/needless_option_take.rs:23:5 | LL | x.as_ref().take(); - | ^^^^^^^^^^^^^^^^^ help: try: `x.as_ref()` + | ^^^^^^^^^^^^^^^^^ | + = note: `as_ref` creates a temporary value, so calling take() has no effect = note: `-D clippy::needless-option-take` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::needless_option_take)]` -error: aborting due to 1 previous error +error: called `Option::take()` on a temporary value + --> tests/ui/needless_option_take.rs:31:13 + | +LL | let y = x.as_mut().take(); + | ^^^^^^^^^^^^^^^^^ + | + = note: `as_mut` creates a temporary value, so calling take() has no effect + +error: called `Option::take()` on a temporary value + --> tests/ui/needless_option_take.rs:33:13 + | +LL | let y = x.replace(289).take(); + | ^^^^^^^^^^^^^^^^^^^^^ + | + = note: `replace` creates a temporary value, so calling take() has no effect + +error: called `Option::take()` on a temporary value + --> tests/ui/needless_option_take.rs:36:13 + | +LL | let y = Some(3).as_mut().take(); + | ^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: `as_mut` creates a temporary value, so calling take() has no effect + +error: called `Option::take()` on a temporary value + --> tests/ui/needless_option_take.rs:39:13 + | +LL | let y = Option::as_mut(&mut x).take(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: `as_mut` creates a temporary value, so calling take() has no effect + +error: called `Option::take()` on a temporary value + --> tests/ui/needless_option_take.rs:43:13 + | +LL | let x = return_option().take(); + | ^^^^^^^^^^^^^^^^^^^^^^ + | + = note: `return_option` creates a temporary value, so calling take() has no effect + +error: called `Option::take()` on a temporary value + --> tests/ui/needless_option_take.rs:47:13 + | +LL | let x = MyStruct::get_option().take(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: `get_option` creates a temporary value, so calling take() has no effect + +error: called `Option::take()` on a temporary value + --> tests/ui/needless_option_take.rs:53:13 + | +LL | let y = my_vec.first().take(); + | ^^^^^^^^^^^^^^^^^^^^^ + | + = note: `first` creates a temporary value, so calling take() has no effect + +error: called `Option::take()` on a temporary value + --> tests/ui/needless_option_take.rs:56:13 + | +LL | let y = my_vec.first().take(); + | ^^^^^^^^^^^^^^^^^^^^^ + | + = note: `first` creates a temporary value, so calling take() has no effect + +error: aborting due to 9 previous errors