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| 1 | +use clippy_utils::consts::constant_simple; |
| 2 | +use clippy_utils::diagnostics::span_lint_and_sugg; |
| 3 | +use clippy_utils::source::{indent_of, reindent_multiline, snippet_opt}; |
| 4 | +use clippy_utils::ty::is_type_diagnostic_item; |
| 5 | +use clippy_utils::usage::contains_return_break_continue_macro; |
| 6 | +use clippy_utils::{is_lang_ctor, path_to_local_id, sugg}; |
| 7 | +use if_chain::if_chain; |
| 8 | +use rustc_errors::Applicability; |
| 9 | +use rustc_hir::LangItem::{OptionNone, OptionSome, ResultErr, ResultOk}; |
| 10 | +use rustc_hir::{Arm, Expr, PatKind}; |
| 11 | +use rustc_lint::LateContext; |
| 12 | +use rustc_span::sym; |
| 13 | + |
| 14 | +use super::MANUAL_UNWRAP_OR; |
| 15 | + |
| 16 | +pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>, scrutinee: &'tcx Expr<'_>, arms: &'tcx [Arm<'_>]) { |
| 17 | + let ty = cx.typeck_results().expr_ty(scrutinee); |
| 18 | + if_chain! { |
| 19 | + if let Some(ty_name) = if is_type_diagnostic_item(cx, ty, sym::Option) { |
| 20 | + Some("Option") |
| 21 | + } else if is_type_diagnostic_item(cx, ty, sym::Result) { |
| 22 | + Some("Result") |
| 23 | + } else { |
| 24 | + None |
| 25 | + }; |
| 26 | + if let Some(or_arm) = applicable_or_arm(cx, arms); |
| 27 | + if let Some(or_body_snippet) = snippet_opt(cx, or_arm.body.span); |
| 28 | + if let Some(indent) = indent_of(cx, expr.span); |
| 29 | + if constant_simple(cx, cx.typeck_results(), or_arm.body).is_some(); |
| 30 | + then { |
| 31 | + let reindented_or_body = |
| 32 | + reindent_multiline(or_body_snippet.into(), true, Some(indent)); |
| 33 | + |
| 34 | + let suggestion = if scrutinee.span.from_expansion() { |
| 35 | + // we don't want parentheses around macro, e.g. `(some_macro!()).unwrap_or(0)` |
| 36 | + sugg::Sugg::hir_with_macro_callsite(cx, scrutinee, "..") |
| 37 | + } |
| 38 | + else { |
| 39 | + sugg::Sugg::hir(cx, scrutinee, "..").maybe_par() |
| 40 | + }; |
| 41 | + |
| 42 | + span_lint_and_sugg( |
| 43 | + cx, |
| 44 | + MANUAL_UNWRAP_OR, expr.span, |
| 45 | + &format!("this pattern reimplements `{}::unwrap_or`", ty_name), |
| 46 | + "replace with", |
| 47 | + format!( |
| 48 | + "{}.unwrap_or({})", |
| 49 | + suggestion, |
| 50 | + reindented_or_body, |
| 51 | + ), |
| 52 | + Applicability::MachineApplicable, |
| 53 | + ); |
| 54 | + } |
| 55 | + } |
| 56 | +} |
| 57 | + |
| 58 | +fn applicable_or_arm<'a>(cx: &LateContext<'_>, arms: &'a [Arm<'a>]) -> Option<&'a Arm<'a>> { |
| 59 | + if_chain! { |
| 60 | + if arms.len() == 2; |
| 61 | + if arms.iter().all(|arm| arm.guard.is_none()); |
| 62 | + if let Some((idx, or_arm)) = arms.iter().enumerate().find(|(_, arm)| { |
| 63 | + match arm.pat.kind { |
| 64 | + PatKind::Path(ref qpath) => is_lang_ctor(cx, qpath, OptionNone), |
| 65 | + PatKind::TupleStruct(ref qpath, [pat], _) => |
| 66 | + matches!(pat.kind, PatKind::Wild) && is_lang_ctor(cx, qpath, ResultErr), |
| 67 | + _ => false, |
| 68 | + } |
| 69 | + }); |
| 70 | + let unwrap_arm = &arms[1 - idx]; |
| 71 | + if let PatKind::TupleStruct(ref qpath, [unwrap_pat], _) = unwrap_arm.pat.kind; |
| 72 | + if is_lang_ctor(cx, qpath, OptionSome) || is_lang_ctor(cx, qpath, ResultOk); |
| 73 | + if let PatKind::Binding(_, binding_hir_id, ..) = unwrap_pat.kind; |
| 74 | + if path_to_local_id(unwrap_arm.body, binding_hir_id); |
| 75 | + if cx.typeck_results().expr_adjustments(unwrap_arm.body).is_empty(); |
| 76 | + if !contains_return_break_continue_macro(or_arm.body); |
| 77 | + then { |
| 78 | + Some(or_arm) |
| 79 | + } else { |
| 80 | + None |
| 81 | + } |
| 82 | + } |
| 83 | +} |
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