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https://github.com/rust-lang/rust-clippy
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Enhance manual flatten
This commit is contained in:
nahuakang
parent
b87e189694
commit
e07cd5b6fe
3 changed files with 104 additions and 71 deletions
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@ -1996,52 +1996,82 @@ fn check_manual_flatten<'tcx>(
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body: &'tcx Expr<'_>,
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span: Span,
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) {
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if_chain! {
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// Ensure the `if let` statement is the only expression in the for-loop
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if let ExprKind::Block(ref block, _) = body.kind;
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if block.stmts.is_empty();
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if let Some(inner_expr) = block.expr;
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if let ExprKind::Match(
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ref match_expr, ref match_arms, MatchSource::IfLetDesugar{ contains_else_clause: false }
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) = inner_expr.kind;
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// Ensure match_expr in `if let` statement is the same as the pat from the for-loop
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if let PatKind::Binding(_, pat_hir_id, _, _) = pat.kind;
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if let ExprKind::Path(QPath::Resolved(None, match_expr_path)) = match_expr.kind;
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if let Res::Local(match_expr_path_id) = match_expr_path.res;
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if pat_hir_id == match_expr_path_id;
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// Ensure the `if let` statement is for the `Some` variant of `Option` or the `Ok` variant of `Result`
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if let PatKind::TupleStruct(QPath::Resolved(None, path), _, _) = match_arms[0].pat.kind;
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if is_some_ctor(cx, path.res) || is_ok_ctor(cx, path.res);
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let if_let_type = if is_some_ctor(cx, path.res) {
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"Some"
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} else {
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"Ok"
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};
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// Determine if `arg` is `Iterator` or implicitly calls `into_iter`
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let arg_ty = cx.typeck_results().expr_ty(arg);
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if let Some(id) = get_trait_def_id(cx, &paths::ITERATOR);
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if let is_iterator = implements_trait(cx, arg_ty, id, &[]);
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then {
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// Prepare the error message
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let msg = format!("Unnecessary `if let` since only the `{}` variant of the iterator element is used.", if_let_type);
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// Prepare the help message
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let arg_snippet = snippet(cx, arg.span, "..");
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let hint = if is_iterator {
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format!("try: `{}.flatten()`", arg_snippet)
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if let ExprKind::Block(ref block, _) = body.kind {
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// Ensure the `if let` statement is the only expression or statement in the for-loop
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let inner_expr = if block.stmts.len() == 1 && block.expr.is_none() {
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let match_stmt = &block.stmts[0];
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if let StmtKind::Semi(inner_expr) = match_stmt.kind {
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Some(inner_expr)
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} else {
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format!("try: `{}.into_iter().flatten()`", arg_snippet)
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};
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None
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}
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} else if block.stmts.is_empty() {
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block.expr
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} else {
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None
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};
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span_lint_and_help(
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cx,
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MANUAL_FLATTEN,
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span,
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&msg,
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Some(arg.span),
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&hint,
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);
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if_chain! {
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if let Some(inner_expr) = inner_expr;
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if let ExprKind::Match(
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ref match_expr, ref match_arms, MatchSource::IfLetDesugar{ contains_else_clause: false }
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) = inner_expr.kind;
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// Ensure match_expr in `if let` statement is the same as the pat from the for-loop
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if let PatKind::Binding(_, pat_hir_id, _, _) = pat.kind;
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if let ExprKind::Path(QPath::Resolved(None, match_expr_path)) = match_expr.kind;
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if let Res::Local(match_expr_path_id) = match_expr_path.res;
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if pat_hir_id == match_expr_path_id;
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// Ensure the `if let` statement is for the `Some` variant of `Option` or the `Ok` variant of `Result`
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if let PatKind::TupleStruct(QPath::Resolved(None, path), _, _) = match_arms[0].pat.kind;
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let some_ctor = is_some_ctor(cx, path.res);
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let ok_ctor = is_ok_ctor(cx, path.res);
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if some_ctor || ok_ctor;
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let if_let_type = if some_ctor { "Some" } else { "Ok" };
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then {
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// Prepare the error message
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let msg = format!("unnecessary `if let` since only the `{}` variant of the iterator element is used", if_let_type);
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// Prepare the help message
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let mut applicability = Applicability::MaybeIncorrect;
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let arg_snippet = snippet_with_applicability(
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cx,
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arg.span,
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"..",
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&mut applicability,
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);
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// Determine if `arg` is by reference, an `Iterator`, or implicitly adjusted with `into_iter`
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let hint = match arg.kind {
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ExprKind::AddrOf(_, _, arg_expr) => {
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format!("{}.iter().flatten()", snippet(cx, arg_expr.span, ".."))
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},
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ExprKind::MethodCall(_, _, _, _) | ExprKind::Path(QPath::Resolved(None, _)) => {
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// Determine if `arg` is `Iterator` or implicitly calls `into_iter`
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let arg_ty = cx.typeck_results().expr_ty(arg);
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if let Some(id) = get_trait_def_id(cx, &paths::ITERATOR) {
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let is_iterator = implements_trait(cx, arg_ty, id, &[]);
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if is_iterator {
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format!("{}.flatten()", arg_snippet)
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} else {
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format!("{}.into_iter().flatten()", arg_snippet)
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}
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} else {
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return
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}
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},
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_ => return,
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};
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span_lint_and_sugg(
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cx,
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MANUAL_FLATTEN,
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span,
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&msg,
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"try",
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hint,
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applicability,
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)
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}
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}
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}
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}
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@ -1,6 +1,7 @@
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#![warn(clippy::manual_flatten)]
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fn main() {
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// Test for loop over implicitly adjusted `Iterator` with `if let` expression
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let x = vec![Some(1), Some(2), Some(3)];
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for n in x {
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if let Some(n) = n {
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@ -8,13 +9,22 @@ fn main() {
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}
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}
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// Test for loop over implicitly implicitly adjusted `Iterator` with `if let` statement
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let y: Vec<Result<i32, i32>> = vec![];
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for n in y.clone() {
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if let Ok(n) = n {
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println!("{}", n);
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};
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}
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// Test for loop over by reference
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for n in &y {
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if let Ok(n) = n {
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println!("{}", n);
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}
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}
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// Test for loop over `Iterator` with `if let` expression
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let z = vec![Some(1), Some(2), Some(3)];
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let z = z.iter();
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for n in z {
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@ -1,51 +1,44 @@
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error: Unnecessary `if let` since only the `Some` variant of the iterator element is used.
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--> $DIR/manual_flatten.rs:5:5
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error: unnecessary `if let` since only the `Some` variant of the iterator element is used
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--> $DIR/manual_flatten.rs:6:5
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LL | / for n in x {
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LL | | if let Some(n) = n {
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LL | | println!("{}", n);
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LL | | }
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LL | | }
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| |_____^
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| |_____^ help: try: `x.into_iter().flatten()`
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= note: `-D clippy::manual-flatten` implied by `-D warnings`
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help: try: `x.into_iter().flatten()`
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--> $DIR/manual_flatten.rs:5:14
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LL | for n in x {
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| ^
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error: Unnecessary `if let` since only the `Ok` variant of the iterator element is used.
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--> $DIR/manual_flatten.rs:12:5
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error: unnecessary `if let` since only the `Ok` variant of the iterator element is used
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--> $DIR/manual_flatten.rs:14:5
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LL | / for n in y.clone() {
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LL | | if let Ok(n) = n {
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LL | | println!("{}", n);
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LL | | };
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LL | | }
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| |_____^ help: try: `y.clone().into_iter().flatten()`
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error: unnecessary `if let` since only the `Ok` variant of the iterator element is used
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--> $DIR/manual_flatten.rs:21:5
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LL | / for n in &y {
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LL | | if let Ok(n) = n {
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LL | | println!("{}", n);
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LL | | }
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LL | | }
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| |_____^
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help: try: `y.clone().into_iter().flatten()`
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--> $DIR/manual_flatten.rs:12:14
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LL | for n in y.clone() {
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| ^^^^^^^^^
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| |_____^ help: try: `y.iter().flatten()`
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error: Unnecessary `if let` since only the `Some` variant of the iterator element is used.
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--> $DIR/manual_flatten.rs:20:5
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error: unnecessary `if let` since only the `Some` variant of the iterator element is used
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--> $DIR/manual_flatten.rs:30:5
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LL | / for n in z {
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LL | | if let Some(n) = n {
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LL | | println!("{}", n);
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LL | | }
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LL | | }
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| |_____^
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help: try: `z.flatten()`
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--> $DIR/manual_flatten.rs:20:14
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LL | for n in z {
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| ^
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| |_____^ help: try: `z.flatten()`
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error: aborting due to 3 previous errors
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error: aborting due to 4 previous errors
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