| use clippy_utils::diagnostics::span_lint_and_sugg; |
| use clippy_utils::get_parent_expr; |
| use clippy_utils::ty::implements_trait; |
| use rustc_errors::Applicability; |
| use rustc_hir::{Expr, ExprKind}; |
| use rustc_lint::LateContext; |
| use rustc_middle::ty; |
| use rustc_span::{sym, Span}; |
| |
| use super::UNNECESSARY_FALLIBLE_CONVERSIONS; |
| |
| /// What function is being called and whether that call is written as a method call or a function |
| /// call |
| #[derive(Copy, Clone)] |
| #[expect(clippy::enum_variant_names)] |
| enum FunctionKind { |
| /// `T::try_from(U)` |
| TryFromFunction, |
| /// `t.try_into()` |
| TryIntoMethod, |
| /// `U::try_into(t)` |
| TryIntoFunction, |
| } |
| |
| fn check<'tcx>( |
| cx: &LateContext<'tcx>, |
| expr: &Expr<'_>, |
| node_args: ty::GenericArgsRef<'tcx>, |
| kind: FunctionKind, |
| primary_span: Span, |
| ) { |
| if let &[self_ty, other_ty] = node_args.as_slice() |
| // useless_conversion already warns `T::try_from(T)`, so ignore it here |
| && self_ty != other_ty |
| && let Some(self_ty) = self_ty.as_type() |
| && let Some(from_into_trait) = cx.tcx.get_diagnostic_item(match kind { |
| FunctionKind::TryFromFunction => sym::From, |
| FunctionKind::TryIntoMethod | FunctionKind::TryIntoFunction => sym::Into, |
| }) |
| // If `T: TryFrom<U>` and `T: From<U>` both exist, then that means that the `TryFrom` |
| // _must_ be from the blanket impl and cannot have been manually implemented |
| // (else there would be conflicting impls, even with #![feature(spec)]), so we don't even need to check |
| // what `<T as TryFrom<U>>::Error` is: it's always `Infallible` |
| && implements_trait(cx, self_ty, from_into_trait, &[other_ty]) |
| { |
| let parent_unwrap_call = get_parent_expr(cx, expr).and_then(|parent| { |
| if let ExprKind::MethodCall(path, .., span) = parent.kind |
| && let sym::unwrap | sym::expect = path.ident.name |
| { |
| Some(span) |
| } else { |
| None |
| } |
| }); |
| |
| let (sugg, span, applicability) = match kind { |
| FunctionKind::TryIntoMethod if let Some(unwrap_span) = parent_unwrap_call => { |
| // Extend the span to include the unwrap/expect call: |
| // `foo.try_into().expect("..")` |
| // ^^^^^^^^^^^^^^^^^^^^^^^ |
| // |
| // `try_into().unwrap()` specifically can be trivially replaced with just `into()`, |
| // so that can be machine-applicable |
| |
| ( |
| "into()", |
| primary_span.with_hi(unwrap_span.hi()), |
| Applicability::MachineApplicable, |
| ) |
| }, |
| FunctionKind::TryFromFunction => ("From::from", primary_span, Applicability::Unspecified), |
| FunctionKind::TryIntoFunction => ("Into::into", primary_span, Applicability::Unspecified), |
| FunctionKind::TryIntoMethod => ("into", primary_span, Applicability::Unspecified), |
| }; |
| |
| span_lint_and_sugg( |
| cx, |
| UNNECESSARY_FALLIBLE_CONVERSIONS, |
| span, |
| "use of a fallible conversion when an infallible one could be used", |
| "use", |
| sugg.into(), |
| applicability, |
| ); |
| } |
| } |
| |
| /// Checks method call exprs: |
| /// - `0i32.try_into()` |
| pub(super) fn check_method(cx: &LateContext<'_>, expr: &Expr<'_>) { |
| if let ExprKind::MethodCall(path, ..) = expr.kind { |
| check( |
| cx, |
| expr, |
| cx.typeck_results().node_args(expr.hir_id), |
| FunctionKind::TryIntoMethod, |
| path.ident.span, |
| ); |
| } |
| } |
| |
| /// Checks function call exprs: |
| /// - `<i64 as TryFrom<_>>::try_from(0i32)` |
| /// - `<_ as TryInto<i64>>::try_into(0i32)` |
| pub(super) fn check_function(cx: &LateContext<'_>, expr: &Expr<'_>, callee: &Expr<'_>) { |
| if let ExprKind::Path(ref qpath) = callee.kind |
| && let Some(item_def_id) = cx.qpath_res(qpath, callee.hir_id).opt_def_id() |
| && let Some(trait_def_id) = cx.tcx.trait_of_item(item_def_id) |
| { |
| check( |
| cx, |
| expr, |
| cx.typeck_results().node_args(callee.hir_id), |
| match cx.tcx.get_diagnostic_name(trait_def_id) { |
| Some(sym::TryFrom) => FunctionKind::TryFromFunction, |
| Some(sym::TryInto) => FunctionKind::TryIntoFunction, |
| _ => return, |
| }, |
| callee.span, |
| ); |
| } |
| } |