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| 1 | +use clippy_utils::consts::{constant, Constant}; |
| 2 | +use clippy_utils::diagnostics::span_lint_and_sugg; |
| 3 | +use clippy_utils::source::snippet_with_context; |
| 4 | +use clippy_utils::{is_diag_item_method, match_def_path, paths}; |
| 5 | +use if_chain::if_chain; |
| 6 | +use rustc_errors::Applicability; |
| 7 | +use rustc_hir::{Expr, ExprKind, HirId, LangItem, Node, QPath}; |
| 8 | +use rustc_lint::LateContext; |
| 9 | +use rustc_middle::ty::{self, adjustment::Adjust}; |
| 10 | +use rustc_span::{symbol::sym, Span, SyntaxContext}; |
| 11 | + |
| 12 | +use super::MANUAL_SPLIT_ONCE; |
| 13 | + |
| 14 | +pub(super) fn check(cx: &LateContext<'_>, method_name: &str, expr: &Expr<'_>, self_arg: &Expr<'_>, pat_arg: &Expr<'_>) { |
| 15 | + if !cx.typeck_results().expr_ty_adjusted(self_arg).peel_refs().is_str() { |
| 16 | + return; |
| 17 | + } |
| 18 | + |
| 19 | + let ctxt = expr.span.ctxt(); |
| 20 | + let usage = match parse_iter_usage(cx, ctxt, cx.tcx.hir().parent_iter(expr.hir_id)) { |
| 21 | + Some(x) => x, |
| 22 | + None => return, |
| 23 | + }; |
| 24 | + let (method_name, msg) = if method_name == "splitn" { |
| 25 | + ("split_once", "manual implementation of `split_once`") |
| 26 | + } else { |
| 27 | + ("rsplit_once", "manual implementation of `rsplit_once`") |
| 28 | + }; |
| 29 | + |
| 30 | + let mut app = Applicability::MachineApplicable; |
| 31 | + let self_snip = snippet_with_context(cx, self_arg.span, ctxt, "..", &mut app).0; |
| 32 | + let pat_snip = snippet_with_context(cx, pat_arg.span, ctxt, "..", &mut app).0; |
| 33 | + |
| 34 | + match usage.kind { |
| 35 | + IterUsageKind::NextTuple => { |
| 36 | + span_lint_and_sugg( |
| 37 | + cx, |
| 38 | + MANUAL_SPLIT_ONCE, |
| 39 | + usage.span, |
| 40 | + msg, |
| 41 | + "try this", |
| 42 | + format!("{}.{}({})", self_snip, method_name, pat_snip), |
| 43 | + app, |
| 44 | + ); |
| 45 | + }, |
| 46 | + IterUsageKind::Next => { |
| 47 | + let self_deref = { |
| 48 | + let adjust = cx.typeck_results().expr_adjustments(self_arg); |
| 49 | + if adjust.is_empty() { |
| 50 | + String::new() |
| 51 | + } else if cx.typeck_results().expr_ty(self_arg).is_box() |
| 52 | + || adjust |
| 53 | + .iter() |
| 54 | + .any(|a| matches!(a.kind, Adjust::Deref(Some(_))) || a.target.is_box()) |
| 55 | + { |
| 56 | + format!("&{}", "*".repeat(adjust.len() - 1)) |
| 57 | + } else { |
| 58 | + "*".repeat(adjust.len() - 2) |
| 59 | + } |
| 60 | + }; |
| 61 | + let sugg = if usage.unwrap_kind.is_some() { |
| 62 | + format!( |
| 63 | + "{}.{}({}).map_or({}{}, |x| x.0)", |
| 64 | + &self_snip, method_name, pat_snip, self_deref, &self_snip |
| 65 | + ) |
| 66 | + } else { |
| 67 | + format!( |
| 68 | + "Some({}.{}({}).map_or({}{}, |x| x.0))", |
| 69 | + &self_snip, method_name, pat_snip, self_deref, &self_snip |
| 70 | + ) |
| 71 | + }; |
| 72 | + |
| 73 | + span_lint_and_sugg(cx, MANUAL_SPLIT_ONCE, usage.span, msg, "try this", sugg, app); |
| 74 | + }, |
| 75 | + IterUsageKind::Second => { |
| 76 | + let access_str = match usage.unwrap_kind { |
| 77 | + Some(UnwrapKind::Unwrap) => ".unwrap().1", |
| 78 | + Some(UnwrapKind::QuestionMark) => "?.1", |
| 79 | + None => ".map(|x| x.1)", |
| 80 | + }; |
| 81 | + span_lint_and_sugg( |
| 82 | + cx, |
| 83 | + MANUAL_SPLIT_ONCE, |
| 84 | + usage.span, |
| 85 | + msg, |
| 86 | + "try this", |
| 87 | + format!("{}.{}({}){}", self_snip, method_name, pat_snip, access_str), |
| 88 | + app, |
| 89 | + ); |
| 90 | + }, |
| 91 | + } |
| 92 | +} |
| 93 | + |
| 94 | +enum IterUsageKind { |
| 95 | + Next, |
| 96 | + Second, |
| 97 | + NextTuple, |
| 98 | +} |
| 99 | + |
| 100 | +enum UnwrapKind { |
| 101 | + Unwrap, |
| 102 | + QuestionMark, |
| 103 | +} |
| 104 | + |
| 105 | +struct IterUsage { |
| 106 | + kind: IterUsageKind, |
| 107 | + unwrap_kind: Option<UnwrapKind>, |
| 108 | + span: Span, |
| 109 | +} |
| 110 | + |
| 111 | +fn parse_iter_usage( |
| 112 | + cx: &LateContext<'tcx>, |
| 113 | + ctxt: SyntaxContext, |
| 114 | + mut iter: impl Iterator<Item = (HirId, Node<'tcx>)>, |
| 115 | +) -> Option<IterUsage> { |
| 116 | + let (kind, span) = match iter.next() { |
| 117 | + Some((_, Node::Expr(e))) if e.span.ctxt() == ctxt => { |
| 118 | + let (name, args) = if let ExprKind::MethodCall(name, _, [_, args @ ..], _) = e.kind { |
| 119 | + (name, args) |
| 120 | + } else { |
| 121 | + return None; |
| 122 | + }; |
| 123 | + let did = cx.typeck_results().type_dependent_def_id(e.hir_id)?; |
| 124 | + let iter_id = cx.tcx.get_diagnostic_item(sym::Iterator)?; |
| 125 | + |
| 126 | + match (&*name.ident.as_str(), args) { |
| 127 | + ("next", []) if cx.tcx.trait_of_item(did) == Some(iter_id) => (IterUsageKind::Next, e.span), |
| 128 | + ("next_tuple", []) => { |
| 129 | + if_chain! { |
| 130 | + if match_def_path(cx, did, &paths::ITERTOOLS_NEXT_TUPLE); |
| 131 | + if let ty::Adt(adt_def, subs) = cx.typeck_results().expr_ty(e).kind(); |
| 132 | + if cx.tcx.is_diagnostic_item(sym::option_type, adt_def.did); |
| 133 | + if let ty::Tuple(subs) = subs.type_at(0).kind(); |
| 134 | + if subs.len() == 2; |
| 135 | + then { |
| 136 | + return Some(IterUsage { kind: IterUsageKind::NextTuple, span: e.span, unwrap_kind: None }); |
| 137 | + } else { |
| 138 | + return None; |
| 139 | + } |
| 140 | + } |
| 141 | + }, |
| 142 | + ("nth" | "skip", [idx_expr]) if cx.tcx.trait_of_item(did) == Some(iter_id) => { |
| 143 | + if let Some((Constant::Int(idx), _)) = constant(cx, cx.typeck_results(), idx_expr) { |
| 144 | + let span = if name.ident.as_str() == "nth" { |
| 145 | + e.span |
| 146 | + } else { |
| 147 | + if_chain! { |
| 148 | + if let Some((_, Node::Expr(next_expr))) = iter.next(); |
| 149 | + if let ExprKind::MethodCall(next_name, _, [_], _) = next_expr.kind; |
| 150 | + if next_name.ident.name == sym::next; |
| 151 | + if next_expr.span.ctxt() == ctxt; |
| 152 | + if let Some(next_id) = cx.typeck_results().type_dependent_def_id(next_expr.hir_id); |
| 153 | + if cx.tcx.trait_of_item(next_id) == Some(iter_id); |
| 154 | + then { |
| 155 | + next_expr.span |
| 156 | + } else { |
| 157 | + return None; |
| 158 | + } |
| 159 | + } |
| 160 | + }; |
| 161 | + match idx { |
| 162 | + 0 => (IterUsageKind::Next, span), |
| 163 | + 1 => (IterUsageKind::Second, span), |
| 164 | + _ => return None, |
| 165 | + } |
| 166 | + } else { |
| 167 | + return None; |
| 168 | + } |
| 169 | + }, |
| 170 | + _ => return None, |
| 171 | + } |
| 172 | + }, |
| 173 | + _ => return None, |
| 174 | + }; |
| 175 | + |
| 176 | + let (unwrap_kind, span) = if let Some((_, Node::Expr(e))) = iter.next() { |
| 177 | + match e.kind { |
| 178 | + ExprKind::Call( |
| 179 | + Expr { |
| 180 | + kind: ExprKind::Path(QPath::LangItem(LangItem::TryTraitBranch, _)), |
| 181 | + .. |
| 182 | + }, |
| 183 | + _, |
| 184 | + ) if e.span.parent().unwrap().ctxt() == ctxt => (Some(UnwrapKind::QuestionMark), e.span), |
| 185 | + _ if e.span.ctxt() != ctxt => (None, span), |
| 186 | + ExprKind::MethodCall(name, _, [_], _) |
| 187 | + if name.ident.name == sym::unwrap |
| 188 | + && cx |
| 189 | + .typeck_results() |
| 190 | + .type_dependent_def_id(e.hir_id) |
| 191 | + .map_or(false, |id| is_diag_item_method(cx, id, sym::option_type)) => |
| 192 | + { |
| 193 | + (Some(UnwrapKind::Unwrap), e.span) |
| 194 | + }, |
| 195 | + _ => (None, span), |
| 196 | + } |
| 197 | + } else { |
| 198 | + (None, span) |
| 199 | + }; |
| 200 | + |
| 201 | + Some(IterUsage { |
| 202 | + kind, |
| 203 | + unwrap_kind, |
| 204 | + span, |
| 205 | + }) |
| 206 | +} |
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