diff options
| -rw-r--r-- | clippy_lints/src/operators/identity_op.rs | 211 | ||||
| -rw-r--r-- | tests/ui/identity_op.fixed | 42 | ||||
| -rw-r--r-- | tests/ui/identity_op.rs | 40 | ||||
| -rw-r--r-- | tests/ui/identity_op.stderr | 64 |
4 files changed, 252 insertions, 105 deletions
diff --git a/clippy_lints/src/operators/identity_op.rs b/clippy_lints/src/operators/identity_op.rs index 830be50c8ba..d8430f6492d 100644 --- a/clippy_lints/src/operators/identity_op.rs +++ b/clippy_lints/src/operators/identity_op.rs @@ -42,83 +42,53 @@ pub(crate) fn check<'tcx>( match op { BinOpKind::Add | BinOpKind::BitOr | BinOpKind::BitXor => { - let _ = check_op( - cx, - left, - 0, - expr.span, - peeled_right_span, - needs_parenthesis(cx, expr, right), - right_is_coerced_to_value, - ) || check_op( - cx, - right, - 0, - expr.span, - peeled_left_span, - Parens::Unneeded, - left_is_coerced_to_value, - ); + if is_redundant_op(cx, left, 0) { + let paren = needs_parenthesis(cx, expr, right); + span_ineffective_operation(cx, expr.span, peeled_right_span, paren, right_is_coerced_to_value); + } else if is_redundant_op(cx, right, 0) { + let paren = needs_parenthesis(cx, expr, left); + span_ineffective_operation(cx, expr.span, peeled_left_span, paren, left_is_coerced_to_value); + } }, BinOpKind::Shl | BinOpKind::Shr | BinOpKind::Sub => { - let _ = check_op( - cx, - right, - 0, - expr.span, - peeled_left_span, - Parens::Unneeded, - left_is_coerced_to_value, - ); + if is_redundant_op(cx, right, 0) { + span_ineffective_operation( + cx, + expr.span, + peeled_left_span, + Parens::Unneeded, + left_is_coerced_to_value, + ); + } }, BinOpKind::Mul => { - let _ = check_op( - cx, - left, - 1, - expr.span, - peeled_right_span, - needs_parenthesis(cx, expr, right), - right_is_coerced_to_value, - ) || check_op( - cx, - right, - 1, - expr.span, - peeled_left_span, - Parens::Unneeded, - left_is_coerced_to_value, - ); + if is_redundant_op(cx, left, 1) { + let paren = needs_parenthesis(cx, expr, right); + span_ineffective_operation(cx, expr.span, peeled_right_span, paren, right_is_coerced_to_value); + } else if is_redundant_op(cx, right, 1) { + let paren = needs_parenthesis(cx, expr, left); + span_ineffective_operation(cx, expr.span, peeled_left_span, paren, left_is_coerced_to_value); + } }, BinOpKind::Div => { - let _ = check_op( - cx, - right, - 1, - expr.span, - peeled_left_span, - Parens::Unneeded, - left_is_coerced_to_value, - ); + if is_redundant_op(cx, right, 1) { + span_ineffective_operation( + cx, + expr.span, + peeled_left_span, + Parens::Unneeded, + left_is_coerced_to_value, + ); + } }, BinOpKind::BitAnd => { - let _ = check_op( - cx, - left, - -1, - expr.span, - peeled_right_span, - needs_parenthesis(cx, expr, right), - right_is_coerced_to_value, - ) || check_op( - cx, - right, - -1, - expr.span, - peeled_left_span, - Parens::Unneeded, - left_is_coerced_to_value, - ); + if is_redundant_op(cx, left, -1) { + let paren = needs_parenthesis(cx, expr, right); + span_ineffective_operation(cx, expr.span, peeled_right_span, paren, right_is_coerced_to_value); + } else if is_redundant_op(cx, right, -1) { + let paren = needs_parenthesis(cx, expr, left); + span_ineffective_operation(cx, expr.span, peeled_left_span, paren, left_is_coerced_to_value); + } }, BinOpKind::Rem => check_remainder(cx, left, right, expr.span, left.span), _ => (), @@ -138,43 +108,75 @@ enum Parens { Unneeded, } -/// Checks if `left op right` needs parenthesis when reduced to `right` +/// Checks if a binary expression needs parenthesis when reduced to just its +/// right or left child. +/// +/// e.g. `-(x + y + 0)` cannot be reduced to `-x + y`, as the behavior changes silently. +/// e.g. `1u64 + ((x + y + 0i32) as u64)` cannot be reduced to `1u64 + x + y as u64`, since +/// the the cast expression will not apply to the same expression. /// e.g. `0 + if b { 1 } else { 2 } + if b { 3 } else { 4 }` cannot be reduced /// to `if b { 1 } else { 2 } + if b { 3 } else { 4 }` where the `if` could be -/// interpreted as a statement +/// interpreted as a statement. The same behavior happens for `match`, `loop`, +/// and blocks. +/// e.g. `2 * (0 + { a })` can be reduced to `2 * { a }` without the need for parenthesis, +/// but `1 * ({ a } + 4)` cannot be reduced to `{ a } + 4`, as a block at the start of a line +/// will be interpreted as a statement instead of an expression. /// -/// See #8724 -fn needs_parenthesis(cx: &LateContext<'_>, binary: &Expr<'_>, right: &Expr<'_>) -> Parens { - match right.kind { +/// See #8724, #13470 +fn needs_parenthesis(cx: &LateContext<'_>, binary: &Expr<'_>, child: &Expr<'_>) -> Parens { + match child.kind { ExprKind::Binary(_, lhs, _) | ExprKind::Cast(lhs, _) => { - // ensure we're checking against the leftmost expression of `right` - // - // ~~~ `lhs` - // 0 + {4} * 2 - // ~~~~~~~ `right` - return needs_parenthesis(cx, binary, lhs); + // For casts and binary expressions, we want to add parenthesis if + // the parent HIR node is an expression with a different precedence, + // or if the parent HIR node is a Block or Stmt, and the new left hand side + // would be treated as a statement rather than an expression. + if let Some((_, parent)) = cx.tcx.hir().parent_iter(binary.hir_id).next() { + if let Node::Expr(expr) = parent { + if child.precedence().order() != expr.precedence().order() { + return Parens::Needed; + } + return Parens::Unneeded; + } + match parent { + Node::Block(_) | Node::Stmt(_) => { + // ensure we're checking against the leftmost expression of `child` + // + // ~~~~~~~~~~~ `binary` + // ~~~ `lhs` + // 0 + {4} * 2 + // ~~~~~~~ `child` + return needs_parenthesis(cx, binary, lhs); + }, + _ => return Parens::Unneeded, + } + } }, - ExprKind::If(..) | ExprKind::Match(..) | ExprKind::Block(..) | ExprKind::Loop(..) => {}, - _ => return Parens::Unneeded, - } + ExprKind::If(..) | ExprKind::Match(..) | ExprKind::Block(..) | ExprKind::Loop(..) => { + // For if, match, block, and loop expressions, we want to add parenthesis if + // the closest ancestor node that is not an expression is a block or statement. + // This would mean that the rustfix suggestion will appear at the start of a line, which causes + // these expressions to be interpreted as statements if they do not have parenthesis. + let mut prev_id = binary.hir_id; + for (_, parent) in cx.tcx.hir().parent_iter(binary.hir_id) { + if let Node::Expr(expr) = parent + && let ExprKind::Binary(_, lhs, _) | ExprKind::Cast(lhs, _) | ExprKind::Unary(_, lhs) = expr.kind + && lhs.hir_id == prev_id + { + // keep going until we find a node that encompasses left of `binary` + prev_id = expr.hir_id; + continue; + } - let mut prev_id = binary.hir_id; - for (_, node) in cx.tcx.hir().parent_iter(binary.hir_id) { - if let Node::Expr(expr) = node - && let ExprKind::Binary(_, lhs, _) | ExprKind::Cast(lhs, _) = expr.kind - && lhs.hir_id == prev_id - { - // keep going until we find a node that encompasses left of `binary` - prev_id = expr.hir_id; - continue; - } - - match node { - Node::Block(_) | Node::Stmt(_) => break, - _ => return Parens::Unneeded, - }; + match parent { + Node::Block(_) | Node::Stmt(_) => return Parens::Needed, + _ => return Parens::Unneeded, + }; + } + }, + _ => { + return Parens::Unneeded; + }, } - Parens::Needed } @@ -199,7 +201,7 @@ fn check_remainder(cx: &LateContext<'_>, left: &Expr<'_>, right: &Expr<'_>, span } } -fn check_op(cx: &LateContext<'_>, e: &Expr<'_>, m: i8, span: Span, arg: Span, parens: Parens, is_erased: bool) -> bool { +fn is_redundant_op(cx: &LateContext<'_>, e: &Expr<'_>, m: i8) -> bool { if let Some(Constant::Int(v)) = ConstEvalCtxt::new(cx).eval_simple(e).map(Constant::peel_refs) { let check = match *cx.typeck_results().expr_ty(e).peel_refs().kind() { ty::Int(ity) => unsext(cx.tcx, -1_i128, ity), @@ -212,7 +214,6 @@ fn check_op(cx: &LateContext<'_>, e: &Expr<'_>, m: i8, span: Span, arg: Span, pa 1 => v == 1, _ => unreachable!(), } { - span_ineffective_operation(cx, span, arg, parens, is_erased); return true; } } @@ -234,7 +235,13 @@ fn span_ineffective_operation( expr_snippet.into_owned() }; let suggestion = match parens { - Parens::Needed => format!("({expr_snippet})"), + Parens::Needed => { + if !expr_snippet.starts_with('(') && !expr_snippet.ends_with(')') { + format!("({expr_snippet})") + } else { + expr_snippet + } + }, Parens::Unneeded => expr_snippet, }; diff --git a/tests/ui/identity_op.fixed b/tests/ui/identity_op.fixed index b18d8560f6f..18b7401768d 100644 --- a/tests/ui/identity_op.fixed +++ b/tests/ui/identity_op.fixed @@ -149,7 +149,7 @@ fn main() { 2 * { a }; //~^ ERROR: this operation has no effect - (({ a } + 4)); + ({ a } + 4); //~^ ERROR: this operation has no effect 1; //~^ ERROR: this operation has no effect @@ -212,3 +212,43 @@ fn issue_12050() { //~^ ERROR: this operation has no effect } } + +fn issue_13470() { + let x = 1i32; + let y = 1i32; + // Removes the + 0i32 while keeping the parentheses around x + y so the cast operation works + let _: u64 = (x + y) as u64; + //~^ ERROR: this operation has no effect + // both of the next two lines should look the same after rustfix + let _: u64 = 1u64 & (x + y) as u64; + //~^ ERROR: this operation has no effect + // Same as above, but with extra redundant parenthesis + let _: u64 = 1u64 & (x + y) as u64; + //~^ ERROR: this operation has no effect + // Should maintain parenthesis even if the surrounding expr has the same precedence + let _: u64 = 5u64 + (x + y) as u64; + //~^ ERROR: this operation has no effect + + // If we don't maintain the parens here, the behavior changes + let _ = -(x + y); + //~^ ERROR: this operation has no effect + // Maintain parenthesis if the parent expr is of higher precedence + let _ = 2i32 * (x + y); + //~^ ERROR: this operation has no effect + // No need for parenthesis if the parent expr is of equal precedence + let _ = 2i32 + x + y; + //~^ ERROR: this operation has no effect + // But make sure that inner parens still exist + let z = 1i32; + let _ = 2 + x + (y * z); + //~^ ERROR: this operation has no effect + // Maintain parenthesis if the parent expr is of lower precedence + // This is for clarity, and clippy will not warn on these being unnecessary + let _ = 2i32 + (x * y); + //~^ ERROR: this operation has no effect + + let x = 1i16; + let y = 1i16; + let _: u64 = 1u64 + (x as i32 + y as i32) as u64; + //~^ ERROR: this operation has no effect +} diff --git a/tests/ui/identity_op.rs b/tests/ui/identity_op.rs index f1f01b42447..55483f4e5fb 100644 --- a/tests/ui/identity_op.rs +++ b/tests/ui/identity_op.rs @@ -212,3 +212,43 @@ fn issue_12050() { //~^ ERROR: this operation has no effect } } + +fn issue_13470() { + let x = 1i32; + let y = 1i32; + // Removes the + 0i32 while keeping the parentheses around x + y so the cast operation works + let _: u64 = (x + y + 0i32) as u64; + //~^ ERROR: this operation has no effect + // both of the next two lines should look the same after rustfix + let _: u64 = 1u64 & (x + y + 0i32) as u64; + //~^ ERROR: this operation has no effect + // Same as above, but with extra redundant parenthesis + let _: u64 = 1u64 & ((x + y) + 0i32) as u64; + //~^ ERROR: this operation has no effect + // Should maintain parenthesis even if the surrounding expr has the same precedence + let _: u64 = 5u64 + ((x + y) + 0i32) as u64; + //~^ ERROR: this operation has no effect + + // If we don't maintain the parens here, the behavior changes + let _ = -(x + y + 0i32); + //~^ ERROR: this operation has no effect + // Maintain parenthesis if the parent expr is of higher precedence + let _ = 2i32 * (x + y + 0i32); + //~^ ERROR: this operation has no effect + // No need for parenthesis if the parent expr is of equal precedence + let _ = 2i32 + (x + y + 0i32); + //~^ ERROR: this operation has no effect + // But make sure that inner parens still exist + let z = 1i32; + let _ = 2 + (x + (y * z) + 0); + //~^ ERROR: this operation has no effect + // Maintain parenthesis if the parent expr is of lower precedence + // This is for clarity, and clippy will not warn on these being unnecessary + let _ = 2i32 + (x * y * 1i32); + //~^ ERROR: this operation has no effect + + let x = 1i16; + let y = 1i16; + let _: u64 = 1u64 + ((x as i32 + y as i32) as u64 + 0u64); + //~^ ERROR: this operation has no effect +} diff --git a/tests/ui/identity_op.stderr b/tests/ui/identity_op.stderr index 9fff86b86f9..856bebfa1ff 100644 --- a/tests/ui/identity_op.stderr +++ b/tests/ui/identity_op.stderr @@ -221,7 +221,7 @@ error: this operation has no effect --> tests/ui/identity_op.rs:152:5 | LL | 1 * ({ a } + 4); - | ^^^^^^^^^^^^^^^ help: consider reducing it to: `(({ a } + 4))` + | ^^^^^^^^^^^^^^^ help: consider reducing it to: `({ a } + 4)` error: this operation has no effect --> tests/ui/identity_op.rs:154:5 @@ -313,5 +313,65 @@ error: this operation has no effect LL | let _: i32 = **&&*&x + 0; | ^^^^^^^^^^^ help: consider reducing it to: `***&&*&x` -error: aborting due to 52 previous errors +error: this operation has no effect + --> tests/ui/identity_op.rs:220:18 + | +LL | let _: u64 = (x + y + 0i32) as u64; + | ^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)` + +error: this operation has no effect + --> tests/ui/identity_op.rs:223:25 + | +LL | let _: u64 = 1u64 & (x + y + 0i32) as u64; + | ^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)` + +error: this operation has no effect + --> tests/ui/identity_op.rs:226:25 + | +LL | let _: u64 = 1u64 & ((x + y) + 0i32) as u64; + | ^^^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)` + +error: this operation has no effect + --> tests/ui/identity_op.rs:229:25 + | +LL | let _: u64 = 5u64 + ((x + y) + 0i32) as u64; + | ^^^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)` + +error: this operation has no effect + --> tests/ui/identity_op.rs:233:14 + | +LL | let _ = -(x + y + 0i32); + | ^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)` + +error: this operation has no effect + --> tests/ui/identity_op.rs:236:20 + | +LL | let _ = 2i32 * (x + y + 0i32); + | ^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)` + +error: this operation has no effect + --> tests/ui/identity_op.rs:239:20 + | +LL | let _ = 2i32 + (x + y + 0i32); + | ^^^^^^^^^^^^^^ help: consider reducing it to: `x + y` + +error: this operation has no effect + --> tests/ui/identity_op.rs:243:17 + | +LL | let _ = 2 + (x + (y * z) + 0); + | ^^^^^^^^^^^^^^^^^ help: consider reducing it to: `x + (y * z)` + +error: this operation has no effect + --> tests/ui/identity_op.rs:247:20 + | +LL | let _ = 2i32 + (x * y * 1i32); + | ^^^^^^^^^^^^^^ help: consider reducing it to: `(x * y)` + +error: this operation has no effect + --> tests/ui/identity_op.rs:252:25 + | +LL | let _: u64 = 1u64 + ((x as i32 + y as i32) as u64 + 0u64); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider reducing it to: `(x as i32 + y as i32) as u64` + +error: aborting due to 62 previous errors |