1 use clippy_utils::diagnostics::span_lint_and_sugg;
2 use clippy_utils::sugg::Sugg;
3 use clippy_utils::ty::is_type_diagnostic_item;
4 use if_chain::if_chain;
5 use rustc_errors::Applicability;
6 use rustc_hir::{def, Expr, ExprKind, PrimTy, QPath, TyKind};
7 use rustc_lint::{LateContext, LateLintPass};
8 use rustc_middle::ty::Ty;
9 use rustc_session::{declare_lint_pass, declare_tool_lint};
10 use rustc_span::symbol::sym;
12 declare_clippy_lint! {
14 /// Checks for function invocations of the form `primitive::from_str_radix(s, 10)`
16 /// **Why is this bad?**
17 /// This specific common use case can be rewritten as `s.parse::<primitive>()`
18 /// (and in most cases, the turbofish can be removed), which reduces code length
21 /// **Known problems:**
22 /// This lint may suggest using (&<expression>).parse() instead of <expression>.parse() directly
23 /// in some cases, which is correct but adds unnecessary complexity to the code.
28 /// let input: &str = get_input();
29 /// let num = u16::from_str_radix(input, 10)?;
33 /// let input: &str = get_input();
34 /// let num: u16 = input.parse()?;
36 pub FROM_STR_RADIX_10,
38 "from_str_radix with radix 10"
41 declare_lint_pass!(FromStrRadix10 => [FROM_STR_RADIX_10]);
43 impl LateLintPass<'tcx> for FromStrRadix10 {
44 fn check_expr(&mut self, cx: &LateContext<'tcx>, exp: &Expr<'tcx>) {
46 if let ExprKind::Call(maybe_path, arguments) = &exp.kind;
47 if let ExprKind::Path(QPath::TypeRelative(ty, pathseg)) = &maybe_path.kind;
49 // check if the first part of the path is some integer primitive
50 if let TyKind::Path(ty_qpath) = &ty.kind;
51 let ty_res = cx.qpath_res(ty_qpath, ty.hir_id);
52 if let def::Res::PrimTy(prim_ty) = ty_res;
53 if matches!(prim_ty, PrimTy::Int(_) | PrimTy::Uint(_));
55 // check if the second part of the path indeed calls the associated
56 // function `from_str_radix`
57 if pathseg.ident.name.as_str() == "from_str_radix";
59 // check if the second argument is a primitive `10`
60 if arguments.len() == 2;
61 if let ExprKind::Lit(lit) = &arguments[1].kind;
62 if let rustc_ast::ast::LitKind::Int(10, _) = lit.node;
65 let expr = if let ExprKind::AddrOf(_, _, expr) = &arguments[0].kind {
66 let ty = cx.typeck_results().expr_ty(expr);
67 if is_ty_stringish(cx, ty) {
76 let sugg = Sugg::hir_with_applicability(
80 &mut Applicability::MachineApplicable
87 "this call to `from_str_radix` can be replaced with a call to `str::parse`",
89 format!("{}.parse::<{}>()", sugg, prim_ty.name_str()),
90 Applicability::MaybeIncorrect
97 /// Checks if a Ty is `String` or `&str`
98 fn is_ty_stringish(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
99 is_type_diagnostic_item(cx, ty, sym::string_type) || is_type_diagnostic_item(cx, ty, sym::str)