--- /dev/null
+use if_chain::if_chain;
+use rustc_errors::Applicability;
+use rustc_hir::{def, Expr, ExprKind, PrimTy, QPath, TyKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::Ty;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::symbol::sym;
+
+use crate::utils::is_type_diagnostic_item;
+use crate::utils::span_lint_and_sugg;
+use crate::utils::sugg::Sugg;
+
+declare_clippy_lint! {
+ /// **What it does:**
+ /// Checks for function invocations of the form `primitive::from_str_radix(s, 10)`
+ ///
+ /// **Why is this bad?**
+ /// This specific common use case can be rewritten as `s.parse::<primitive>()`
+ /// (and in most cases, the turbofish can be removed), which reduces code length
+ /// and complexity.
+ ///
+ /// **Known problems:**
+ /// This lint may suggest using (&<expression>).parse() instead of <expression>.parse() directly
+ /// in some cases, which is correct but adds unnecessary complexity to the code.
+ ///
+ /// **Example:**
+ ///
+ /// ```ignore
+ /// let input: &str = get_input();
+ /// let num = u16::from_str_radix(input, 10)?;
+ /// ```
+ /// Use instead:
+ /// ```ignore
+ /// let input: &str = get_input();
+ /// let num: u16 = input.parse()?;
+ /// ```
+ pub FROM_STR_RADIX_10,
+ style,
+ "from_str_radix with radix 10"
+}
+
+declare_lint_pass!(FromStrRadix10 => [FROM_STR_RADIX_10]);
+
+impl LateLintPass<'tcx> for FromStrRadix10 {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, exp: &Expr<'tcx>) {
+ if_chain! {
+ if let ExprKind::Call(maybe_path, arguments) = &exp.kind;
+ if let ExprKind::Path(QPath::TypeRelative(ty, pathseg)) = &maybe_path.kind;
+
+ // check if the first part of the path is some integer primitive
+ if let TyKind::Path(ty_qpath) = &ty.kind;
+ let ty_res = cx.qpath_res(ty_qpath, ty.hir_id);
+ if let def::Res::PrimTy(prim_ty) = ty_res;
+ if matches!(prim_ty, PrimTy::Int(_) | PrimTy::Uint(_));
+
+ // check if the second part of the path indeed calls the associated
+ // function `from_str_radix`
+ if pathseg.ident.name.as_str() == "from_str_radix";
+
+ // check if the second argument is a primitive `10`
+ if arguments.len() == 2;
+ if let ExprKind::Lit(lit) = &arguments[1].kind;
+ if let rustc_ast::ast::LitKind::Int(10, _) = lit.node;
+
+ then {
+ let expr = if let ExprKind::AddrOf(_, _, expr) = &arguments[0].kind {
+ let ty = cx.typeck_results().expr_ty(expr);
+ if is_ty_stringish(cx, ty) {
+ expr
+ } else {
+ &arguments[0]
+ }
+ } else {
+ &arguments[0]
+ };
+
+ let sugg = Sugg::hir_with_applicability(
+ cx,
+ expr,
+ "<string>",
+ &mut Applicability::MachineApplicable
+ ).maybe_par();
+
+ span_lint_and_sugg(
+ cx,
+ FROM_STR_RADIX_10,
+ exp.span,
+ "this call to `from_str_radix` can be replaced with a call to `str::parse`",
+ "try",
+ format!("{}.parse::<{}>()", sugg, prim_ty.name_str()),
+ Applicability::MaybeIncorrect
+ );
+ }
+ }
+ }
+}
+
+/// Checks if a Ty is `String` or `&str`
+fn is_ty_stringish(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
+ is_type_diagnostic_item(cx, ty, sym::string_type) || is_type_diagnostic_item(cx, ty, sym::str)
+}