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| 1 | +use if_chain::if_chain; |
| 2 | +use rustc_errors::Applicability; |
| 3 | +use rustc_hir::{def, Expr, ExprKind, PrimTy, QPath, TyKind}; |
| 4 | +use rustc_lint::{LateContext, LateLintPass}; |
| 5 | +use rustc_middle::ty::Ty; |
| 6 | +use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| 7 | +use rustc_span::symbol::sym; |
| 8 | + |
| 9 | +use crate::utils::is_type_diagnostic_item; |
| 10 | +use crate::utils::span_lint_and_sugg; |
| 11 | +use crate::utils::sugg::Sugg; |
| 12 | + |
| 13 | +declare_clippy_lint! { |
| 14 | + /// **What it does:** |
| 15 | + /// Checks for function invocations of the form `primitive::from_str_radix(s, 10)` |
| 16 | + /// |
| 17 | + /// **Why is this bad?** |
| 18 | + /// This specific common use case can be rewritten as `s.parse::<primitive>()` |
| 19 | + /// (and in most cases, the turbofish can be removed), which reduces code length |
| 20 | + /// and complexity. |
| 21 | + /// |
| 22 | + /// **Known problems:** |
| 23 | + /// This lint may suggest using (&<expression>).parse() instead of <expression>.parse() directly |
| 24 | + /// in some cases, which is correct but adds unnecessary complexity to the code. |
| 25 | + /// |
| 26 | + /// **Example:** |
| 27 | + /// |
| 28 | + /// ```ignore |
| 29 | + /// let input: &str = get_input(); |
| 30 | + /// let num = u16::from_str_radix(input, 10)?; |
| 31 | + /// ``` |
| 32 | + /// Use instead: |
| 33 | + /// ```ignore |
| 34 | + /// let input: &str = get_input(); |
| 35 | + /// let num: u16 = input.parse()?; |
| 36 | + /// ``` |
| 37 | + pub FROM_STR_RADIX_10, |
| 38 | + style, |
| 39 | + "from_str_radix with radix 10" |
| 40 | +} |
| 41 | + |
| 42 | +declare_lint_pass!(FromStrRadix10 => [FROM_STR_RADIX_10]); |
| 43 | + |
| 44 | +impl LateLintPass<'tcx> for FromStrRadix10 { |
| 45 | + fn check_expr(&mut self, cx: &LateContext<'tcx>, exp: &Expr<'tcx>) { |
| 46 | + if_chain! { |
| 47 | + if let ExprKind::Call(maybe_path, arguments) = &exp.kind; |
| 48 | + if let ExprKind::Path(QPath::TypeRelative(ty, pathseg)) = &maybe_path.kind; |
| 49 | + |
| 50 | + // check if the first part of the path is some integer primitive |
| 51 | + if let TyKind::Path(ty_qpath) = &ty.kind; |
| 52 | + let ty_res = cx.qpath_res(ty_qpath, ty.hir_id); |
| 53 | + if let def::Res::PrimTy(prim_ty) = ty_res; |
| 54 | + if matches!(prim_ty, PrimTy::Int(_) | PrimTy::Uint(_)); |
| 55 | + |
| 56 | + // check if the second part of the path indeed calls the associated |
| 57 | + // function `from_str_radix` |
| 58 | + if pathseg.ident.name.as_str() == "from_str_radix"; |
| 59 | + |
| 60 | + // check if the second argument is a primitive `10` |
| 61 | + if arguments.len() == 2; |
| 62 | + if let ExprKind::Lit(lit) = &arguments[1].kind; |
| 63 | + if let rustc_ast::ast::LitKind::Int(10, _) = lit.node; |
| 64 | + |
| 65 | + then { |
| 66 | + let expr = if let ExprKind::AddrOf(_, _, expr) = &arguments[0].kind { |
| 67 | + let ty = cx.typeck_results().expr_ty(expr); |
| 68 | + if is_ty_stringish(cx, ty) { |
| 69 | + expr |
| 70 | + } else { |
| 71 | + &arguments[0] |
| 72 | + } |
| 73 | + } else { |
| 74 | + &arguments[0] |
| 75 | + }; |
| 76 | + |
| 77 | + let sugg = Sugg::hir_with_applicability( |
| 78 | + cx, |
| 79 | + expr, |
| 80 | + "<string>", |
| 81 | + &mut Applicability::MachineApplicable |
| 82 | + ).maybe_par(); |
| 83 | + |
| 84 | + span_lint_and_sugg( |
| 85 | + cx, |
| 86 | + FROM_STR_RADIX_10, |
| 87 | + exp.span, |
| 88 | + "this call to `from_str_radix` can be replaced with a call to `str::parse`", |
| 89 | + "try", |
| 90 | + format!("{}.parse::<{}>()", sugg, prim_ty.name_str()), |
| 91 | + Applicability::MaybeIncorrect |
| 92 | + ); |
| 93 | + } |
| 94 | + } |
| 95 | + } |
| 96 | +} |
| 97 | + |
| 98 | +/// Checks if a Ty is `String` or `&str` |
| 99 | +fn is_ty_stringish(cx: &LateContext<'_>, ty: Ty<'_>) -> bool { |
| 100 | + is_type_diagnostic_item(cx, ty, sym::string_type) || is_type_diagnostic_item(cx, ty, sym::str) |
| 101 | +} |
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