Move deref closure builder to clippy_utils::sugg module

Author: ThibsG

clippy_lints/src/methods/search_is_some.rs

@@ -1,21 +1,16 @@
-use std::iter;
-
 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_sugg};
 use clippy_utils::source::{snippet, snippet_with_applicability};
+use clippy_utils::sugg::deref_closure_args;
 use clippy_utils::ty::is_type_diagnostic_item;
-use clippy_utils::{get_parent_expr_for_hir, is_trait_method, strip_pat_refs};
+use clippy_utils::{is_trait_method, strip_pat_refs};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
-use rustc_hir::{self, ExprKind, HirId, MutTy, PatKind, TyKind};
-use rustc_infer::infer::TyCtxtInferExt;
+use rustc_hir::PatKind;
 use rustc_lint::LateContext;
-use rustc_middle::hir::place::ProjectionKind;
-use rustc_middle::mir::{FakeReadCause, Mutability};
 use rustc_middle::ty;
-use rustc_span::source_map::{BytePos, Span};
+use rustc_span::source_map::Span;
 use rustc_span::symbol::sym;
-use rustc_typeck::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
 
 use super::SEARCH_IS_SOME;
 
@@ -55,7 +50,7 @@ pub(super) fn check<'tcx>(
                     } else if let PatKind::Binding(..) = strip_pat_refs(closure_arg.pat).kind {
                         // `find()` provides a reference to the item, but `any` does not,
                         // so we should fix item usages for suggestion
-                        if let Some(closure_sugg) = get_closure_suggestion(cx, search_arg) {
+                        if let Some(closure_sugg) = deref_closure_args(cx, search_arg) {
                             applicability = closure_sugg.applicability;
                             Some(closure_sugg.suggestion)
                         } else {
@@ -159,246 +154,3 @@ pub(super) fn check<'tcx>(
         }
     }
 }
-
-#[derive(Debug)]
-struct ClosureSugg {
-    applicability: Applicability,
-    suggestion: String,
-}
-
-// Build suggestion gradually by handling closure arg specific usages,
-// such as explicit deref and borrowing cases.
-// Returns `None` if no such use cases have been triggered in closure body
-fn get_closure_suggestion<'tcx>(cx: &LateContext<'_>, search_expr: &'tcx hir::Expr<'_>) -> Option<ClosureSugg> {
-    if let hir::ExprKind::Closure(_, fn_decl, body_id, ..) = search_expr.kind {
-        let closure_body = cx.tcx.hir().body(body_id);
-        // is closure arg a double reference (i.e.: `|x: &&i32| ...`)
-        let closure_arg_is_double_ref = if let TyKind::Rptr(_, MutTy { ty, .. }) = fn_decl.inputs[0].kind {
-            matches!(ty.kind, TyKind::Rptr(_, MutTy { .. }))
-        } else {
-            false
-        };
-
-        let mut visitor = DerefDelegate {
-            cx,
-            closure_span: search_expr.span,
-            closure_arg_is_double_ref,
-            next_pos: search_expr.span.lo(),
-            suggestion_start: String::new(),
-            applicability: Applicability::MaybeIncorrect,
-        };
-
-        let fn_def_id = cx.tcx.hir().local_def_id(search_expr.hir_id);
-        cx.tcx.infer_ctxt().enter(|infcx| {
-            ExprUseVisitor::new(&mut visitor, &infcx, fn_def_id, cx.param_env, cx.typeck_results())
-                .consume_body(closure_body);
-        });
-
-        if !visitor.suggestion_start.is_empty() {
-            return Some(ClosureSugg {
-                applicability: visitor.applicability,
-                suggestion: visitor.finish(),
-            });
-        }
-    }
-    None
-}
-
-struct DerefDelegate<'a, 'tcx> {
-    cx: &'a LateContext<'tcx>,
-    closure_span: Span,
-    closure_arg_is_double_ref: bool,
-    next_pos: BytePos,
-    suggestion_start: String,
-    applicability: Applicability,
-}
-
-impl DerefDelegate<'_, 'tcx> {
-    pub fn finish(&mut self) -> String {
-        let end_span = Span::new(self.next_pos, self.closure_span.hi(), self.closure_span.ctxt(), None);
-        let end_snip = snippet_with_applicability(self.cx, end_span, "..", &mut self.applicability);
-        let sugg = format!("{}{}", self.suggestion_start, end_snip);
-        if self.closure_arg_is_double_ref {
-            sugg.replacen('&', "", 1)
-        } else {
-            sugg
-        }
-    }
-
-    fn func_takes_arg_by_double_ref(&self, parent_expr: &'tcx hir::Expr<'_>, cmt_hir_id: HirId) -> bool {
-        let (call_args, inputs) = match parent_expr.kind {
-            ExprKind::MethodCall(_, _, call_args, _) => {
-                if let Some(method_did) = self.cx.typeck_results().type_dependent_def_id(parent_expr.hir_id) {
-                    (call_args, self.cx.tcx.fn_sig(method_did).skip_binder().inputs())
-                } else {
-                    return false;
-                }
-            },
-            ExprKind::Call(func, call_args) => {
-                let typ = self.cx.typeck_results().expr_ty(func);
-                (call_args, typ.fn_sig(self.cx.tcx).skip_binder().inputs())
-            },
-            _ => return false,
-        };
-
-        iter::zip(call_args, inputs)
-            .any(|(arg, ty)| arg.hir_id == cmt_hir_id && matches!(ty.kind(), ty::Ref(_, inner, _) if inner.is_ref()))
-    }
-}
-
-impl<'tcx> Delegate<'tcx> for DerefDelegate<'_, 'tcx> {
-    fn consume(&mut self, _: &PlaceWithHirId<'tcx>, _: HirId) {}
-
-    fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId, _: ty::BorrowKind) {
-        if let PlaceBase::Local(id) = cmt.place.base {
-            let map = self.cx.tcx.hir();
-            let span = map.span(cmt.hir_id);
-            let start_span = Span::new(self.next_pos, span.lo(), span.ctxt(), None);
-            let mut start_snip = snippet_with_applicability(self.cx, start_span, "..", &mut self.applicability);
-
-            // identifier referring to the variable currently triggered (i.e.: `fp`)
-            let ident_str = map.name(id).to_string();
-            // full identifier that includes projection (i.e.: `fp.field`)
-            let ident_str_with_proj = snippet(self.cx, span, "..").to_string();
-
-            if cmt.place.projections.is_empty() {
-                // handle item without any projection, that needs an explicit borrowing
-                // i.e.: suggest `&x` instead of `x`
-                self.closure_arg_is_double_ref = false;
-                self.suggestion_start.push_str(&format!("{}&{}", start_snip, ident_str));
-            } else {
-                // cases where a parent `Call` or `MethodCall` is using the item
-                // i.e.: suggest `.contains(&x)` for `.find(|x| [1, 2, 3].contains(x)).is_none()`
-                //
-                // Note about method calls:
-                // - compiler automatically dereference references if the target type is a reference (works also for
-                //   function call)
-                // - `self` arguments in the case of `x.is_something()` are also automatically (de)referenced, and
-                //   no projection should be suggested
-                if let Some(parent_expr) = get_parent_expr_for_hir(self.cx, cmt.hir_id) {
-                    match &parent_expr.kind {
-                        // given expression is the self argument and will be handled completely by the compiler
-                        // i.e.: `|x| x.is_something()`
-                        ExprKind::MethodCall(_, _, [self_expr, ..], _) if self_expr.hir_id == cmt.hir_id => {
-                            self.suggestion_start
-                                .push_str(&format!("{}{}", start_snip, ident_str_with_proj));
-                            self.next_pos = span.hi();
-                            return;
-                        },
-                        // item is used in a call
-                        // i.e.: `Call`: `|x| please(x)` or `MethodCall`: `|x| [1, 2, 3].contains(x)`
-                        ExprKind::Call(_, [call_args @ ..]) | ExprKind::MethodCall(_, _, [_, call_args @ ..], _) => {
-                            let expr = self.cx.tcx.hir().expect_expr(cmt.hir_id);
-                            let arg_ty_kind = self.cx.typeck_results().expr_ty(expr).kind();
-
-                            if matches!(arg_ty_kind, ty::Ref(_, _, Mutability::Not)) {
-                                // suggest ampersand if call function is taking args by double reference
-                                let takes_arg_by_double_ref =
-                                    self.func_takes_arg_by_double_ref(parent_expr, cmt.hir_id);
-
-                                // compiler will automatically dereference field projection, so no need
-                                // to suggest ampersand, but full identifier that includes projection is required
-                                let has_field_projection = cmt
-                                    .place
-                                    .projections
-                                    .iter()
-                                    .any(|proj| matches!(proj.kind, ProjectionKind::Field(..)));
-
-                                // no need to bind again if the function doesn't take arg by double ref
-                                // and if the item is already a double ref
-                                let ident_sugg = if !call_args.is_empty()
-                                    && !takes_arg_by_double_ref
-                                    && (self.closure_arg_is_double_ref || has_field_projection)
-                                {
-                                    let ident = if has_field_projection {
-                                        ident_str_with_proj
-                                    } else {
-                                        ident_str
-                                    };
-                                    format!("{}{}", start_snip, ident)
-                                } else {
-                                    format!("{}&{}", start_snip, ident_str)
-                                };
-                                self.suggestion_start.push_str(&ident_sugg);
-                                self.next_pos = span.hi();
-                                return;
-                            }
-
-                            self.applicability = Applicability::Unspecified;
-                        },
-                        _ => (),
-                    }
-                }
-
-                let mut replacement_str = ident_str;
-                let mut projections_handled = false;
-                cmt.place.projections.iter().enumerate().for_each(|(i, proj)| {
-                    match proj.kind {
-                        // Field projection like `|v| v.foo`
-                        // no adjustment needed here, as field projections are handled by the compiler
-                        ProjectionKind::Field(..) => match cmt.place.ty_before_projection(i).kind() {
-                            ty::Adt(..) | ty::Tuple(_) => {
-                                replacement_str = ident_str_with_proj.clone();
-                                projections_handled = true;
-                            },
-                            _ => (),
-                        },
-                        // Index projection like `|x| foo[x]`
-                        // the index is dropped so we can't get it to build the suggestion,
-                        // so the span is set-up again to get more code, using `span.hi()` (i.e.: `foo[x]`)
-                        // instead of `span.lo()` (i.e.: `foo`)
-                        ProjectionKind::Index => {
-                            let start_span = Span::new(self.next_pos, span.hi(), span.ctxt(), None);
-                            start_snip = snippet_with_applicability(self.cx, start_span, "..", &mut self.applicability);
-                            replacement_str.clear();
-                            projections_handled = true;
-                        },
-                        // note: unable to trigger `Subslice` kind in tests
-                        ProjectionKind::Subslice => (),
-                        ProjectionKind::Deref => {
-                            // explicit deref for arrays should be avoided in the suggestion
-                            // i.e.: `|sub| *sub[1..4].len() == 3` is not expected
-                            if let ty::Ref(_, inner, _) = cmt.place.ty_before_projection(i).kind() {
-                                // dereferencing an array (i.e.: `|sub| sub[1..4].len() == 3`)
-                                if matches!(inner.kind(), ty::Ref(_, innermost, _) if innermost.is_array()) {
-                                    projections_handled = true;
-                                }
-                            }
-                        },
-                    }
-                });
-
-                // handle `ProjectionKind::Deref` by removing one explicit deref
-                // if no special case was detected (i.e.: suggest `*x` instead of `**x`)
-                if projections_handled {
-                    self.closure_arg_is_double_ref = false;
-                } else {
-                    let last_deref = cmt
-                        .place
-                        .projections
-                        .iter()
-                        .rposition(|proj| proj.kind == ProjectionKind::Deref);
-
-                    if let Some(pos) = last_deref {
-                        let mut projections = cmt.place.projections.clone();
-                        projections.truncate(pos);
-
-                        for item in projections {
-                            if item.kind == ProjectionKind::Deref {
-                                replacement_str = format!("*{}", replacement_str);
-                            }
-                        }
-                    }
-                }
-
-                self.suggestion_start
-                    .push_str(&format!("{}{}", start_snip, replacement_str));
-            }
-            self.next_pos = span.hi();
-        }
-    }
-
-    fn mutate(&mut self, _: &PlaceWithHirId<'tcx>, _: HirId) {}
-
-    fn fake_read(&mut self, _: rustc_typeck::expr_use_visitor::Place<'tcx>, _: FakeReadCause, _: HirId) {}
-}