separate the receiver from arguments in HIR under /clippy

Author: TaKO8Ki

book/src/development/common_tools_writing_lints.md

@@ -66,7 +66,7 @@ Starting with an `expr`, you can check whether it is calling a specific method
 impl<'tcx> LateLintPass<'tcx> for MyStructLint {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
         // Check our expr is calling a method
-        if let hir::ExprKind::MethodCall(path, _, [_self_arg, ..]) = &expr.kind
+        if let hir::ExprKind::MethodCall(path, _, _self_arg, ..) = &expr.kind
             // Check the name of this method is `some_method`
             && path.ident.name == sym!(some_method)
             // Optionally, check the type of the self argument.

clippy_lints/src/assertions_on_result_states.rs

@@ -43,7 +43,7 @@ impl<'tcx> LateLintPass<'tcx> for AssertionsOnResultStates {
             && matches!(cx.tcx.get_diagnostic_name(macro_call.def_id), Some(sym::assert_macro))
             && let Some((condition, panic_expn)) = find_assert_args(cx, e, macro_call.expn)
             && matches!(panic_expn, PanicExpn::Empty)
-            && let ExprKind::MethodCall(method_segment, [recv], _) = condition.kind
+            && let ExprKind::MethodCall(method_segment, recv, [], _) = condition.kind
             && let result_type_with_refs = cx.typeck_results().expr_ty(recv)
             && let result_type = result_type_with_refs.peel_refs()
             && is_type_diagnostic_item(cx, result_type, sym::Result)

clippy_lints/src/blocks_in_if_conditions.rs

@@ -55,7 +55,7 @@ impl<'a, 'tcx> Visitor<'tcx> for ExVisitor<'a, 'tcx> {
             // do not lint if the closure is called using an iterator (see #1141)
             if_chain! {
                 if let Some(parent) = get_parent_expr(self.cx, expr);
-                if let ExprKind::MethodCall(_, [self_arg, ..], _) = &parent.kind;
+                if let ExprKind::MethodCall(_, self_arg, ..) = &parent.kind;
                 let caller = self.cx.typeck_results().expr_ty(self_arg);
                 if let Some(iter_id) = self.cx.tcx.get_diagnostic_item(sym::Iterator);
                 if implements_trait(self.cx, caller, iter_id, &[]);
@@ -117,7 +117,8 @@ impl<'tcx> LateLintPass<'tcx> for BlocksInIfConditions {
                             );
                         }
                     } else {
-                        let span = block.expr.as_ref().map_or_else(|| block.stmts[0].span, |e| e.span);
+                        let span =
+                            block.expr.as_ref().map_or_else(|| block.stmts[0].span, |e| e.span);
                         if span.from_expansion() || expr.span.from_expansion() {
                             return;
                         }

clippy_lints/src/booleans.rs

@@ -270,8 +270,8 @@ fn simplify_not(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
                 ))
             })
         },
-        ExprKind::MethodCall(path, args, _) if args.len() == 1 => {
-            let type_of_receiver = cx.typeck_results().expr_ty(&args[0]);
+        ExprKind::MethodCall(path, receiver, [], _) => {
+            let type_of_receiver = cx.typeck_results().expr_ty(receiver);
             if !is_type_diagnostic_item(cx, type_of_receiver, sym::Option)
                 && !is_type_diagnostic_item(cx, type_of_receiver, sym::Result)
             {
@@ -285,7 +285,7 @@ fn simplify_not(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
                     let path: &str = path.ident.name.as_str();
                     a == path
                 })
-                .and_then(|(_, neg_method)| Some(format!("{}.{}()", snippet_opt(cx, args[0].span)?, neg_method)))
+                .and_then(|(_, neg_method)| Some(format!("{}.{}()", snippet_opt(cx, receiver.span)?, neg_method)))
         },
         _ => None,
     }

clippy_lints/src/casts/cast_abs_to_unsigned.rs

@@ -20,7 +20,7 @@ pub(super) fn check(
     if meets_msrv(msrv, msrvs::UNSIGNED_ABS)
         && let ty::Int(from) = cast_from.kind()
         && let ty::Uint(to) = cast_to.kind()
-        && let ExprKind::MethodCall(method_path, args, _) = cast_expr.kind
+        && let ExprKind::MethodCall(method_path, receiver, ..) = cast_expr.kind
         && method_path.ident.name.as_str() == "abs"
     {
         let span = if from.bit_width() == to.bit_width() {
@@ -37,7 +37,7 @@ pub(super) fn check(
             span,
             &format!("casting the result of `{cast_from}::abs()` to {cast_to}"),
             "replace with",
-            format!("{}.unsigned_abs()", Sugg::hir(cx, &args[0], "..").maybe_par()),
+            format!("{}.unsigned_abs()", Sugg::hir(cx, receiver, "..").maybe_par()),
             Applicability::MachineApplicable,
         );
     }

clippy_lints/src/casts/cast_possible_truncation.rs

@@ -44,7 +44,7 @@ fn apply_reductions(cx: &LateContext<'_>, nbits: u64, expr: &Expr<'_>, signed: b
                 .saturating_sub(constant_int(cx, right).map_or(0, |s| u64::try_from(s).expect("shift too high"))),
             _ => nbits,
         },
-        ExprKind::MethodCall(method, [left, right], _) => {
+        ExprKind::MethodCall(method, left, [right], _) => {
             if signed {
                 return nbits;
             }
@@ -55,7 +55,7 @@ fn apply_reductions(cx: &LateContext<'_>, nbits: u64, expr: &Expr<'_>, signed: b
             };
             apply_reductions(cx, nbits, left, signed).min(max_bits.unwrap_or(u64::max_value()))
         },
-        ExprKind::MethodCall(method, [_, lo, hi], _) => {
+        ExprKind::MethodCall(method, _, [lo, hi], _) => {
             if method.ident.as_str() == "clamp" {
                 //FIXME: make this a diagnostic item
                 if let (Some(lo_bits), Some(hi_bits)) = (get_constant_bits(cx, lo), get_constant_bits(cx, hi)) {
@@ -64,7 +64,7 @@ fn apply_reductions(cx: &LateContext<'_>, nbits: u64, expr: &Expr<'_>, signed: b
             }
             nbits
         },
-        ExprKind::MethodCall(method, [_value], _) => {
+        ExprKind::MethodCall(method, _value, [], _) => {
             if method.ident.name.as_str() == "signum" {
                 0 // do not lint if cast comes from a `signum` function
             } else {

clippy_lints/src/casts/cast_ptr_alignment.rs

@@ -18,7 +18,7 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>) {
             cx.typeck_results().expr_ty(expr),
         );
         lint_cast_ptr_alignment(cx, expr, cast_from, cast_to);
-    } else if let ExprKind::MethodCall(method_path, [self_arg, ..], _) = &expr.kind {
+    } else if let ExprKind::MethodCall(method_path, self_arg, ..) = &expr.kind {
         if method_path.ident.name == sym!(cast)
             && let Some(generic_args) = method_path.args
             && let [GenericArg::Type(cast_to)] = generic_args.args
@@ -64,7 +64,7 @@ fn is_used_as_unaligned(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
         return false;
     };
     match parent.kind {
-        ExprKind::MethodCall(name, [self_arg, ..], _) if self_arg.hir_id == e.hir_id => {
+        ExprKind::MethodCall(name, self_arg, ..) if self_arg.hir_id == e.hir_id => {
             if matches!(name.ident.as_str(), "read_unaligned" | "write_unaligned")
                 && let Some(def_id) = cx.typeck_results().type_dependent_def_id(parent.hir_id)
                 && let Some(def_id) = cx.tcx.impl_of_method(def_id)

clippy_lints/src/casts/cast_sign_loss.rs

@@ -41,14 +41,14 @@ fn should_lint(cx: &LateContext<'_>, cast_op: &Expr<'_>, cast_from: Ty<'_>, cast
             }
 
             // Don't lint for the result of methods that always return non-negative values.
-            if let ExprKind::MethodCall(path, _, _) = cast_op.kind {
+            if let ExprKind::MethodCall(path, ..) = cast_op.kind {
                 let mut method_name = path.ident.name.as_str();
                 let allowed_methods = ["abs", "checked_abs", "rem_euclid", "checked_rem_euclid"];
 
                 if_chain! {
                     if method_name == "unwrap";
                     if let Some(arglist) = method_chain_args(cast_op, &["unwrap"]);
-                    if let ExprKind::MethodCall(inner_path, _, _) = &arglist[0][0].kind;
+                    if let ExprKind::MethodCall(inner_path, ..) = &arglist[0].0.kind;
                     then {
                         method_name = inner_path.ident.name.as_str();
                     }

clippy_lints/src/default_numeric_fallback.rs

@@ -69,10 +69,7 @@ struct NumericFallbackVisitor<'a, 'tcx> {
 
 impl<'a, 'tcx> NumericFallbackVisitor<'a, 'tcx> {
     fn new(cx: &'a LateContext<'tcx>) -> Self {
-        Self {
-            ty_bounds: vec![TyBound::Nothing],
-            cx,
-        }
+        Self { ty_bounds: vec![TyBound::Nothing], cx }
     }
 
     /// Check whether a passed literal has potential to cause fallback or not.
@@ -129,19 +126,21 @@ impl<'a, 'tcx> Visitor<'tcx> for NumericFallbackVisitor<'a, 'tcx> {
                     }
                     return;
                 }
-            },
+            }
 
-            ExprKind::MethodCall(_, args, _) => {
+            ExprKind::MethodCall(_, receiver, args, _) => {
                 if let Some(def_id) = self.cx.typeck_results().type_dependent_def_id(expr.hir_id) {
                     let fn_sig = self.cx.tcx.fn_sig(def_id).skip_binder();
-                    for (expr, bound) in iter::zip(*args, fn_sig.inputs()) {
+                    for (expr, bound) in
+                        iter::zip(std::iter::once(*receiver).chain(args.iter()), fn_sig.inputs())
+                    {
                         self.ty_bounds.push(TyBound::Ty(*bound));
                         self.visit_expr(expr);
                         self.ty_bounds.pop();
                     }
                     return;
                 }
-            },
+            }
 
             ExprKind::Struct(_, fields, base) => {
                 let ty = self.cx.typeck_results().expr_ty(expr);
@@ -176,15 +175,15 @@ impl<'a, 'tcx> Visitor<'tcx> for NumericFallbackVisitor<'a, 'tcx> {
                         return;
                     }
                 }
-            },
+            }
 
             ExprKind::Lit(lit) => {
                 let ty = self.cx.typeck_results().expr_ty(expr);
                 self.check_lit(lit, ty, expr.hir_id);
                 return;
-            },
+            }
 
-            _ => {},
+            _ => {}
         }
 
         walk_expr(self, expr);
@@ -198,7 +197,7 @@ impl<'a, 'tcx> Visitor<'tcx> for NumericFallbackVisitor<'a, 'tcx> {
                 } else {
                     self.ty_bounds.push(TyBound::Nothing);
                 }
-            },
+            }
 
             _ => self.ty_bounds.push(TyBound::Nothing),
         }

clippy_lints/src/dereference.rs

@@ -581,7 +581,7 @@ fn try_parse_ref_op<'tcx>(
     expr: &'tcx Expr<'_>,
 ) -> Option<(RefOp, &'tcx Expr<'tcx>)> {
     let (def_id, arg) = match expr.kind {
-        ExprKind::MethodCall(_, [arg], _) => (typeck.type_dependent_def_id(expr.hir_id)?, arg),
+        ExprKind::MethodCall(_, arg, [], _) => (typeck.type_dependent_def_id(expr.hir_id)?, arg),
         ExprKind::Call(
             Expr {
                 kind: ExprKind::Path(path),
@@ -796,16 +796,19 @@ fn walk_parents<'tcx>(
                             },
                         })
                     }),
-                ExprKind::MethodCall(_, args, _) => {
+                ExprKind::MethodCall(_, receiver, args, _) => {
                     let id = cx.typeck_results().type_dependent_def_id(parent.hir_id).unwrap();
-                    args.iter().position(|arg| arg.hir_id == child_id).map(|i| {
-                        if i == 0 {
-                            // Check for calls to trait methods where the trait is implemented on a reference.
-                            // Two cases need to be handled:
-                            // * `self` methods on `&T` will never have auto-borrow
-                            // * `&self` methods on `&T` can have auto-borrow, but `&self` methods on `T` will take
-                            //   priority.
-                            if e.hir_id != child_id {
+                    std::iter::once(receiver)
+                        .chain(args.iter())
+                        .position(|arg| arg.hir_id == child_id)
+                        .map(|i| {
+                            if i == 0 {
+                                // Check for calls to trait methods where the trait is implemented on a reference.
+                                // Two cases need to be handled:
+                                // * `self` methods on `&T` will never have auto-borrow
+                                // * `&self` methods on `&T` can have auto-borrow, but `&self` methods on `T` will take
+                                //   priority.
+                                if e.hir_id != child_id {
                                 Position::ReborrowStable(precedence)
                             } else if let Some(trait_id) = cx.tcx.trait_of_item(id)
                                 && let arg_ty = cx.tcx.erase_regions(cx.typeck_results().expr_ty_adjusted(e))
@@ -834,20 +837,20 @@ fn walk_parents<'tcx>(
                             } else {
                                 Position::MethodReceiver
                             }
-                        } else {
-                            let ty = cx.tcx.fn_sig(id).skip_binder().inputs()[i];
-                            if let ty::Param(param_ty) = ty.kind() {
-                                needless_borrow_impl_arg_position(cx, parent, i, *param_ty, e, precedence, msrv)
                             } else {
-                                ty_auto_deref_stability(
-                                    cx,
-                                    cx.tcx.erase_late_bound_regions(cx.tcx.fn_sig(id).input(i)),
-                                    precedence,
-                                )
-                                .position_for_arg()
+                                let ty = cx.tcx.fn_sig(id).skip_binder().inputs()[i];
+                                if let ty::Param(param_ty) = ty.kind() {
+                                    needless_borrow_impl_arg_position(cx, parent, i, *param_ty, e, precedence, msrv)
+                                } else {
+                                    ty_auto_deref_stability(
+                                        cx,
+                                        cx.tcx.erase_late_bound_regions(cx.tcx.fn_sig(id).input(i)),
+                                        precedence,
+                                    )
+                                    .position_for_arg()
+                                }
                             }
-                        }
-                    })
+                        })
                 },
                 ExprKind::Field(child, name) if child.hir_id == e.hir_id => Some(Position::FieldAccess(name.name)),
                 ExprKind::Unary(UnOp::Deref, child) if child.hir_id == e.hir_id => Some(Position::Deref),