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| 1 | +use rustc_ast::{ExprPrecedence, LitKind}; |
| 2 | +use rustc_hir::{Block, ExprKind}; |
| 3 | +use rustc_lint::{LateContext, LateLintPass}; |
| 4 | +use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| 5 | + |
| 6 | +use clippy_utils::{diagnostics::span_lint_and_then, is_else_clause, source::snippet_block_with_applicability}; |
| 7 | +use rustc_errors::Applicability; |
| 8 | + |
| 9 | +declare_clippy_lint! { |
| 10 | + /// ### What it does |
| 11 | + /// Instead of using an if statement to convert a bool to an int, |
| 12 | + /// this lint suggests using a `from()` function or an `as` coercion. |
| 13 | + /// |
| 14 | + /// ### Why is this bad? |
| 15 | + /// Coercion or `from()` is idiomatic way to convert bool to a number. |
| 16 | + /// Both methods are guaranteed to return 1 for true, and 0 for false. |
| 17 | + /// |
| 18 | + /// See https://doc.rust-lang.org/std/primitive.bool.html#impl-From%3Cbool%3E |
| 19 | + /// |
| 20 | + /// ### Example |
| 21 | + /// ```rust |
| 22 | + /// # let condition = false; |
| 23 | + /// if condition { |
| 24 | + /// 1_i64 |
| 25 | + /// } else { |
| 26 | + /// 0 |
| 27 | + /// }; |
| 28 | + /// ``` |
| 29 | + /// Use instead: |
| 30 | + /// ```rust |
| 31 | + /// # let condition = false; |
| 32 | + /// i64::from(condition); |
| 33 | + /// ``` |
| 34 | + /// or |
| 35 | + /// ```rust |
| 36 | + /// # let condition = false; |
| 37 | + /// condition as i64; |
| 38 | + /// ``` |
| 39 | + #[clippy::version = "1.65.0"] |
| 40 | + pub BOOL_TO_INT_WITH_IF, |
| 41 | + style, |
| 42 | + "using if to convert bool to int" |
| 43 | +} |
| 44 | +declare_lint_pass!(BoolToIntWithIf => [BOOL_TO_INT_WITH_IF]); |
| 45 | + |
| 46 | +impl<'tcx> LateLintPass<'tcx> for BoolToIntWithIf { |
| 47 | + fn check_expr(&mut self, ctx: &LateContext<'tcx>, expr: &'tcx rustc_hir::Expr<'tcx>) { |
| 48 | + if !expr.span.from_expansion() { |
| 49 | + check_if_else(ctx, expr); |
| 50 | + } |
| 51 | + } |
| 52 | +} |
| 53 | + |
| 54 | +fn check_if_else<'tcx>(ctx: &LateContext<'tcx>, expr: &'tcx rustc_hir::Expr<'tcx>) { |
| 55 | + if let ExprKind::If(check, then, Some(else_)) = expr.kind |
| 56 | + && let Some(then_lit) = int_literal(then) |
| 57 | + && let Some(else_lit) = int_literal(else_) |
| 58 | + && check_int_literal_equals_val(then_lit, 1) |
| 59 | + && check_int_literal_equals_val(else_lit, 0) |
| 60 | + { |
| 61 | + let mut applicability = Applicability::MachineApplicable; |
| 62 | + let snippet = snippet_block_with_applicability(ctx, check.span, "..", None, &mut applicability); |
| 63 | + let snippet_with_braces = { |
| 64 | + let need_parens = should_have_parentheses(check); |
| 65 | + let (left_paren, right_paren) = if need_parens {("(", ")")} else {("", "")}; |
| 66 | + format!("{left_paren}{snippet}{right_paren}") |
| 67 | + }; |
| 68 | + |
| 69 | + let ty = ctx.typeck_results().expr_ty(then_lit); // then and else must be of same type |
| 70 | + |
| 71 | + let suggestion = { |
| 72 | + let wrap_in_curly = is_else_clause(ctx.tcx, expr); |
| 73 | + let (left_curly, right_curly) = if wrap_in_curly {("{", "}")} else {("", "")}; |
| 74 | + format!( |
| 75 | + "{left_curly}{ty}::from({snippet}){right_curly}" |
| 76 | + ) |
| 77 | + }; // when used in else clause if statement should be wrapped in curly braces |
| 78 | + |
| 79 | + span_lint_and_then(ctx, |
| 80 | + BOOL_TO_INT_WITH_IF, |
| 81 | + expr.span, |
| 82 | + "boolean to int conversion using if", |
| 83 | + |diag| { |
| 84 | + diag.span_suggestion( |
| 85 | + expr.span, |
| 86 | + "replace with from", |
| 87 | + suggestion, |
| 88 | + applicability, |
| 89 | + ); |
| 90 | + diag.note(format!("`{snippet_with_braces} as {ty}` or `{snippet_with_braces}.into()` can also be valid options")); |
| 91 | + }); |
| 92 | + }; |
| 93 | +} |
| 94 | + |
| 95 | +// If block contains only a int literal expression, return literal expression |
| 96 | +fn int_literal<'tcx>(expr: &'tcx rustc_hir::Expr<'tcx>) -> Option<&'tcx rustc_hir::Expr<'tcx>> { |
| 97 | + if let ExprKind::Block(block, _) = expr.kind |
| 98 | + && let Block { |
| 99 | + stmts: [], // Shouldn't lint if statements with side effects |
| 100 | + expr: Some(expr), |
| 101 | + .. |
| 102 | + } = block |
| 103 | + && let ExprKind::Lit(lit) = &expr.kind |
| 104 | + && let LitKind::Int(_, _) = lit.node |
| 105 | + { |
| 106 | + Some(expr) |
| 107 | + } else { |
| 108 | + None |
| 109 | + } |
| 110 | +} |
| 111 | + |
| 112 | +fn check_int_literal_equals_val<'tcx>(expr: &'tcx rustc_hir::Expr<'tcx>, expected_value: u128) -> bool { |
| 113 | + if let ExprKind::Lit(lit) = &expr.kind |
| 114 | + && let LitKind::Int(val, _) = lit.node |
| 115 | + && val == expected_value |
| 116 | + { |
| 117 | + true |
| 118 | + } else { |
| 119 | + false |
| 120 | + } |
| 121 | +} |
| 122 | + |
| 123 | +fn should_have_parentheses<'tcx>(check: &'tcx rustc_hir::Expr<'tcx>) -> bool { |
| 124 | + check.precedence().order() < ExprPrecedence::Cast.order() |
| 125 | +} |
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