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;
9 use crate::utils::is_type_diagnostic_item;
10 use crate::utils::span_lint_and_sugg;
11 use crate::utils::sugg::Sugg;
13 declare_clippy_lint! {
15 /// Checks for function invocations of the form `primitive::from_str_radix(s, 10)`
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
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.
29 /// let input: &str = get_input();
30 /// let num = u16::from_str_radix(input, 10)?;
34 /// let input: &str = get_input();
35 /// let num: u16 = input.parse()?;
37 pub FROM_STR_RADIX_10,
39 "from_str_radix with radix 10"
42 declare_lint_pass!(FromStrRadix10 => [FROM_STR_RADIX_10]);
44 impl LateLintPass<'tcx> for FromStrRadix10 {
45 fn check_expr(&mut self, cx: &LateContext<'tcx>, exp: &Expr<'tcx>) {
47 if let ExprKind::Call(maybe_path, arguments) = &exp.kind;
48 if let ExprKind::Path(QPath::TypeRelative(ty, pathseg)) = &maybe_path.kind;
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(_));
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";
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;
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) {
77 let sugg = Sugg::hir_with_applicability(
81 &mut Applicability::MachineApplicable
88 "this call to `from_str_radix` can be replaced with a call to `str::parse`",
90 format!("{}.parse::<{}>()", sugg, prim_ty.name_str()),
91 Applicability::MaybeIncorrect
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)