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use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::is_integer_literal;
use clippy_utils::sugg::Sugg;
use clippy_utils::ty::is_type_diagnostic_item;
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;
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()?;
/// ```
#[clippy::version = "1.52.0"]
pub FROM_STR_RADIX_10,
style,
"from_str_radix with radix 10"
}
declare_lint_pass!(FromStrRadix10 => [FROM_STR_RADIX_10]);
impl<'tcx> LateLintPass<'tcx> for FromStrRadix10 {
fn check_expr(&mut self, cx: &LateContext<'tcx>, exp: &Expr<'tcx>) {
if_chain! {
if let ExprKind::Call(maybe_path, [src, radix]) = &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 is_integer_literal(radix, 10);
then {
let expr = if let ExprKind::AddrOf(_, _, expr) = &src.kind {
let ty = cx.typeck_results().expr_ty(expr);
if is_ty_stringish(cx, ty) {
expr
} else {
&src
}
} else {
&src
};
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!("{sugg}.parse::<{}>()", 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) || is_type_diagnostic_item(cx, ty, sym::str)
}
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